polyurethane dispersion
{{Short description|Chintan patel}}
Polyurethane dispersion, or PUD, is understood to be a polyurethane polymer resin dispersed in water, rather than a solvent, although some cosolvent may be used. Its manufacture involves the synthesis of polyurethanes having carboxylic acid functionality or nonionic hydrophiles like PEG (polyethylene glycol) incorporated into, or pendant from, the polymer backbone.{{Cite book|title=Comprehensive Biomaterials|url=https://archive.org/details/comprehensivebio00duch|url-access=limited|last1=Ducheyne|first1=Paul|last2=Healy|first2=Kevin|last3=Hutmacher|first3=Dietmar W.|last4=Grainger|first4=David W.|last5=Kirkpatrick|first5=C. James|publisher=Elsevier|year=2015|isbn=9780080553023|location=Amsterdam|pages=[https://archive.org/details/comprehensivebio00duch/page/n426 447]}} Two component polyurethane dispersions are also available.{{Cite journal |last1=Wang |first1=Li |last2=Xu |first2=Fei |last3=Li |first3=Hongxin |last4=Liu |first4=Yangyan |last5=Liu |first5=Yali |date=2017-01-01 |title=Preparation and stability of aqueous acrylic polyol dispersions for two-component waterborne polyurethane |url=https://doi.org/10.1007/s11998-016-9845-x |journal=Journal of Coatings Technology and Research |language=en |volume=14 |issue=1 |pages=215–223 |doi=10.1007/s11998-016-9845-x |issn=1935-3804 |access-date=2023-02-20 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202639/https://link.springer.com/article/10.1007/s11998-016-9845-x |url-status=live }}
Background
There has been a general trend towards converting existing resin systems to waterborne resins, for ease of use and environmental considerations.{{Cite journal|last=Jackson|first=K.|date=1999-07-01|title=Recent advances in water-borne protective coatings|url=https://doi.org/10.1007/BF02720130|journal=Surface Coatings International|language=en|volume=82|issue=7|pages=340–343|doi=10.1007/BF02720130|s2cid=135613088|issn=1356-0751}}{{Cite journal|last=Noreen, Zia & Zuber|date=2015|title=Recent Trends in Environmentally Friendly Water-Borne Polyurethane Coatings|journal=Korean J. Chem. Eng|volume=33|pages=1–13}}{{cite news|url=https://www.linkedin.com/pulse/water-based-polyurethanes-dispersionspuds-an-overview-nikhil-gupta/|title=Water Based Polyurethanes Dispersions(PUDs)-An Overview|date=2015-01-30|access-date=2018-08-21}} Particularly, their development was driven by increased demand for solventless systems since the manufacture of coatings and adhesives entailed the increasing release of solvents into the atmosphere from numerous sources.{{Cite book|title=Ionomers: Synthesis, structure, properties and applications|last1=Tant|first1=M. R.|last2=Mauritz|first2=K. A.|last3=Wilkes|first3=G. L.|publisher=Blackie Academic Professional|year=1997|isbn=9780751403923|location=London|pages=447}} Using VOC exempt solvents is not a panacea as they have their own weaknesses.
The problem has always been that polyurethanes in water are not stable, reacting to produce a urea and carbon dioxide. Many papers and patents have been published on the subject.{{cite journal|date=1981-11-13|title=Aqueous emulsions, dispersions and solutions of polyurethanes; synthesis and properties|journal=Progress in Organic Coatings|volume=9|issue=3|pages=281–340|doi=10.1016/0033-0655(81)80002-7|issn=0300-9440|last1=Dieterich|first1=D}}{{cite web|url=https://patentimages.storage.googleapis.com/c4/28/fd/e286393ae75af4/US3491050.pdf|title=US Patent US3491050}} For environmental reasons there is even a push to have PUD available both water-based and bio-based or made from renewable raw materials.{{cite journal|date=2014-05-01|title=Air-drying bio-based polyurethane dispersion from cardanol: Synthesis and characterization of coatings|journal=Progress in Organic Coatings|volume=77|issue=5|pages=997–1006|doi=10.1016/j.porgcoat.2014.02.006|issn=0300-9440|last1=Patel|first1=Chintankumar J|last2=Mannari |first2=Vijay |bibcode=1992POrCo..20....1B}}{{cite journal|date=2018-04-01|title=High performance polyurethane dispersion synthesized from plant oil renewable resources: A challenge in the green materials|journal=Polymer Degradation and Stability|volume=150|pages=122–132 |doi=10.1016/j.polymdegradstab.2018.02.014|issn=0141-3910|last1=Gurunathan|first1=T|last2=Arukula|first2=Ravi}}{{cite journal|last1=Li|first1=Yingyuan |last2=Noordover |first2=Bart A. J.|last3=van Benthem |first3=Rolf A. T. M.|last4=Koning|first4=Cor E.|date=2014-01-02|title=Reactivity and Regio-Selectivity of Renewable Building Blocks for the Synthesis of Water-Dispersible Polyurethane Prepolymers|journal=ACS Sustainable Chemistry & Engineering|volume=2|issue=4|pages=788–797|doi=10.1021/sc400459q|issn=2168-0485}} PUDs are used because of the general desire to formulate coatings, adhesives, sealants and elastomers based on water rather than solvent, and because of the perceived or assumed benefits to the environment.
Synthesis
The techniques and manufacturing processes have changed over the years from those described in the first papers, journal articles and patents that were published. There are a number of techniques available depending on what type of species is required. An ion may be formed which can be an anion thus forming an anionic PUD or a cation may be formed forming a cationic PUD. Also, it is possible to synthesize a non-ionic PUD.{{cite web|url=https://patentimages.storage.googleapis.com/7a/ed/63/77f3219e6a012c/US3920598.pdf|title=NON-Ionic Polyurethane Dispersions having side-chains of polyoxyethylene}} This involves using materials that will produce an ethylene oxide backbone, or similar, or a water-soluble chain pendant from the main polymer backbone.
Anionic PUDs are by far the most common available commercially. To produce these, initially a polyurethane prepolymer is manufactured in the usual way but instead of just using isocyanate and polyol, a modifier is included in the polymer backbone chain or pendant from the main backbone. This modifier is/was mainly dimethylol propionic acid (DMPA).{{cite web|url=http://www.geosc.com/Assets/Files/Products-Docs/P-C-Product-Docs/Trimet-Products/DMPA_TB5_Waterborne_PUDs_for_Coatings.pdf|title=GEO Specialties Use of DMPA for PUDs}} This molecule contains two hydroxy groups and a carboxylic acid group.{{cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/2_2-Bis_hydroxymethyl_propionic_acid#section=Top|title=Dimethylolpropionic acid|last=Pubchem|website=pubchem.ncbi.nlm.nih.gov|access-date=2018-08-21}} The OH groups react with the isocyanate groups to produce an NCO terminated prepolymer but with a pendant COOH group. This is now dispersed under shear in water with a suitable neutralizing agent such as triethylamine. This reacts with the carboxylic acid forming a salt which is water soluble. Usually, a diamine chain extender is then added to produce a polyurethane dispersed in water with no free NCO groups but with polyurethane and polyurea segments.{{cite journal|last1=Jang|first1=JY|last2=Jhon|first2=YK|last3=Cheong|first3=IW|last4=Kim|first4=JH|date=2002-01-01|title=Colloids and Surfaces A: Physicochem|url=https://www.researchgate.net/publication/286005163|journal=Eng. Aspects|volume=196|pages=135–143}} Dytek A is commonly used as the chain extender.{{Cite journal |last=Howarth |first=GA |date=2003-06-01 |title=Polyurethanes, polyurethane dispersions and polyureas: Past, present and future |url=https://doi.org/10.1007/BF02699621 |journal=Surface Coatings International Part B: Coatings Transactions |language=en |volume=86 |issue=2 |pages=111–118 |doi=10.1007/BF02699621 |s2cid=93574741 |issn=1476-4865}}{{Cite journal |last1=Madbouly |first1=Samy A. |last2=Otaigbe |first2=Joshua U. |last3=Nanda |first3=Ajaya K. |last4=Wicks |first4=Douglas A. |date=2005-05-01 |title=Rheological Behavior of Aqueous Polyurethane Dispersions: Effects of Solid Content, Degree of Neutralization, Chain Extension, and Temperature |url=https://pubs.acs.org/doi/10.1021/ma050453u |journal=Macromolecules |language=en |volume=38 |issue=9 |pages=4014–4023 |doi=10.1021/ma050453u |bibcode=2005MaMol..38.4014M |issn=0024-9297}} Various papers and patents show that an amine chain extender with more than two functionalities such as a triamine may be used too.{{cite journal|last1=Sun|first1=DC|last2=Chen|first2=Q|date=2010-12-01|title=Effect of chain extender and chain extension on properties of high solid content polyurethane dispersion and its film|url=https://www.researchgate.net/publication/288724763|journal=Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering|volume=26|pages=69–72}} Chain extender studies have been carried out.{{Cite journal |last1=Jhon |first1=Young-Kuk |last2=Cheong |first2=In-Woo |last3=Kim |first3=Jung-Hyun |date=2001-04-01 |title=Chain extension study of aqueous polyurethane dispersions |url=https://www.sciencedirect.com/science/article/pii/S0927775700007147 |journal=Colloids and Surfaces A: Physicochemical and Engineering Aspects |language=en |volume=179 |issue=1 |pages=71–78 |doi=10.1016/S0927-7757(00)00714-7 |issn=0927-7757 |access-date=2023-03-09 |archive-date=2015-09-24 |archive-url=https://web.archive.org/web/20150924181513/http://www.sciencedirect.com/science/article/pii/S0927775700007147 |url-status=live }}
There is also a push to have a synthesis strategy that is non-isocyanate based.{{Cite journal|last1=Ma |first1=S |last2=Chen |first2=C|last3=Sablong|first3=RJ|last4=Koning|first4=CE|last5=Benthem|first5=R|date=2018|title=Non-isocyanate strategy for anionically stabilized water-borne polyurea dispersions and coatings|journal=Journal of Polymer Science Part A: Polymer Chemistry |volume=56|issue=10|pages=1078–1090|doi=10.1002/pola.28986|bibcode=2018JPoSA..56.1078M |issn=1099-0518}} When blocked isocyanates are used there is no isocyanate (NCO) functionality and hence the water reaction producing carbon dioxide so dispersion is easier.{{Cite journal|date=2003-11-01|title=New development of polyurethane dispersion derived from blocked aromatic diisocyanate|url=https://www.sciencedirect.com/science/article/pii/S0300944003001188|journal=Progress in Organic Coatings|language=en|volume=48|issue=1|pages=71–79|doi=10.1016/S0300-9440(03)00118-8|issn=0300-9440|last1=Subramani|first1=S.|last2=Park|first2=Young-Jun|last3=Lee|first3=Young-Soo|last4=Kim|first4=Jung-Hyun}} Modifiers other than DMPA have been researched.{{Cite journal |last1=Athawale |first1=Vilas D. |last2=Kulkarni |first2=Mona A. |date=2010-03-01 |title=Synthesis, characterization, and comparison of polyurethane dispersions based on highly versatile anionomer, ATBS, and conventional DMPA |url=https://doi.org/10.1007/s11998-009-9184-2 |journal=Journal of Coatings Technology and Research |language=en |volume=7 |issue=2 |pages=189–199 |doi=10.1007/s11998-009-9184-2 |issn=1935-3804 |access-date=2023-03-09 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202641/https://link.springer.com/article/10.1007/s11998-009-9184-2 |url-status=live }}
It is also possible to introduce hydrophilicity into the polymeric molecule by using a modified chain extender rather than doing so in the polymer backbone or a pendant chain. Lower viscosity materials are often the result, as well as higher solids.{{Cite journal |last1=Zhang |first1=Faxing |last2=Wei |first2=Xiaoli |date=2018-01-01 |title=Study of ionic/nonionic polyurethane dispersions with high solid content and low viscosity using a complex hydrophilic chain-extending agent |url=https://doi.org/10.1007/s11998-017-9965-y |journal=Journal of Coatings Technology and Research |language=en |volume=15 |issue=1 |pages=141–148 |doi=10.1007/s11998-017-9965-y |s2cid=103225551 |issn=1935-3804}} A variation on this technique is to incorporate sulfonate groups. PUD/polyacrylate blends can be prepared this way also utilizing internal emulsifiers.{{Cite journal |last1=Wang |first1=Xiaorong |last2=Ma |first2=Guoyan |last3=Zheng |first3=Minyan |date=2018-11-01 |title=Preparation and characterization of waterborne polyurethane/polyacrylate emulsions containing sulfonate groups |url=https://doi.org/10.1007/s11998-018-0062-7 |journal=Journal of Coatings Technology and Research |language=en |volume=15 |issue=6 |pages=1217–1227 |doi=10.1007/s11998-018-0062-7 |s2cid=104118859 |issn=1935-3804}}
Cationic PUD also introduce hydrophilic components when synthesized. This includes phosphonium entities.{{Cite journal |last1=Zhang |first1=Musan |last2=Hemp |first2=Sean T. |last3=Zhang |first3=Mingqiang |last4=Allen |first4=Michael H. |last5=Carmean |first5=Richard N. |last6=Moore |first6=Robert B. |last7=Long |first7=Timothy E. |date=2014 |title=Water-dispersible cationic polyurethanes containing pendant trialkylphosphoniums |url=http://xlink.rsc.org/?DOI=C3PY01779F |journal=Polym. Chem. |language=en |volume=5 |issue=12 |pages=3795–3803 |doi=10.1039/C3PY01779F |issn=1759-9954|doi-access=free |hdl=10919/51700 |hdl-access=free }} Techniques have and are being researched to improve the performance and water resistance properties by various techniques. This includes introducing star-branched polydimethylsiloxane.{{Cite journal |last1=He |first1=Xiaoling |last2=He |first2=Jingwei |last3=Sun |first3=Yangkun |last4=Zhou |first4=Xiaopei |last5=Zhang |first5=Jingying |last6=Liu |first6=Fang |date=2022-07-01 |title=Preparation and characterization of cationic waterborne polyurethanes containing a star-branched polydimethylsiloxane |url=https://doi.org/10.1007/s11998-021-00584-9 |journal=Journal of Coatings Technology and Research |language=en |volume=19 |issue=4 |pages=1055–1066 |doi=10.1007/s11998-021-00584-9 |s2cid=246946432 |issn=1935-3804}}
Research has been done and published that shows it is not the dispersion speed, mechanical agitation or high shear mixing that has the biggest effect on properties, but rather the chemical makeup. However, particle size distribution can be controlled by this to some extent.{{Cite journal |last1=Phongikaroon |first1=Supathorn |last2=Calabrese |first2=Richard V. |last3=Carpenter |first3=Keith |date=2004-10-01 |title=Elucidation of polyurethane dispersions in a batch rotor-stator mixer |url=https://doi.org/10.1007/s11998-004-0034-y |journal=JCT Research |language=en |volume=1 |issue=4 |pages=329–335 |doi=10.1007/s11998-004-0034-y |s2cid=136692640 |issn=1935-3804}}
Uses
They find use in coatings, adhesives, sealants and elastomers. Specific uses include industrial coatings,{{Cite web|url=http://wernerblank.com/pdfiles/paper12b.pdf|title=FORMULATING POLYURETHANE DISPERSIONS|last=Blank|first=Werner}} UV coating resins,{{Cite journal|last1=Asif|first1=Anila|last2=Huang|first2=Chengyu|last3=Shi|first3=Wenfang|date=2003|title=UV curing behaviors and hydrophilic characteristics of UV curable waterborne hyperbranched aliphatic polyesters|journal=Polymers for Advanced Technologies|language=en|volume=14|issue=9|pages=609–615|doi=10.1002/pat.380|issn=1099-1581}} floor coatings,{{cite web|url=https://www.pharosproject.net/uploads/files/sources/1828/1332269830.pdf|title=Floor Coatings with PUD}} hygiene coatings,{{cite journal|last1=Howarth|first1=G A|last2=Manock|first2=H L|date=July 1997|title=Water-borne polyurethane dispersions and their use in functional coatings|journal=Surface Coatings International|volume=80|issue=7|pages=324–328|doi=10.1007/bf02692680|s2cid=137433262|issn=1356-0751}} wood coatings,{{cite web|url=https://www.pharosproject.net/uploads/files/sources/1828/1332269830.pdf|title=Waterborne Floor Coatings for Wood Floors}} adhesives,{{Cite web|url=https://www.dispersions-pigments.basf.com/portal/basf/ien/dt.jsp?setCursor=1_736943|title=PUD - Polymers - Adhesive Raw Materials - Adhesives - Markets & Industries - BASF Dispersions & Pigments|website=www.dispersions-pigments.basf.com|access-date=2019-04-11}} concrete coatings,{{cite journal|doi = 10.1007/BF02699621|title = Polyurethanes, polyurethane dispersions and polyureas: Past, present and future|journal = Surface Coatings International Part B: Coatings Transactions|volume = 86|issue = 2|pages = 111–118|year = 2003|last1 = Howarth|first1 = GA|s2cid = 93574741}} automotive coatings,{{Cite web|url=https://patentimages.storage.googleapis.com/79/fb/a5/4a3014e443e9ee/US5071904.pdf|title=Patent US5071904A}}{{Cite web|url=https://www.coatings.covestro.com/en/Applications/Automotive-Transportation/OEM-Metal/Metal-basecoat|title=Automotive OEM Metal Metal Basecoat|last=Communications|first=Covestro AG|website=www.coatings.covestro.com|language=en|access-date=2019-04-22}} clear coatings{{Cite web|url=https://www.polygem.com/products/ureseal-water-based-high-gloss-polyurethane-coating|title=URESEAL - Water-Based High-Gloss Polyurethane Coating {{!}} Polygem Epoxy|website=www.polygem.com|access-date=2019-04-26}} and anticorrosive applications.{{Cite journal|last1=Christopher|first1=Gnanaprakasam|last2=Anbu Kulandainathan|first2=Manickam|last3=Harichandran|first3=Gurusamy|date=2015-07-01|title=Highly dispersive waterborne polyurethane/ZnO nanocomposites for corrosion protection|journal=Journal of Coatings Technology and Research|language=en|volume=12|issue=4|pages=657–667|doi=10.1007/s11998-015-9674-3|s2cid=136984192|issn=1935-3804}} They are also used in the design and manufacture of medical devices such as the polyurethane dressing, a liquid bandage based on polyurethane dispersion.{{Cite book|title=The Design and Manufacture of Medical Devices|last=Davim|first=J. Paulo|date=2012-10-16|publisher=Woodhead Publishing|isbn=9781907568725|location=Cambridge, UK|pages=135}} To improve their functionality in flame retardant applications, products are being developed which have this feature built into the polymer molecule.{{Cite journal|last1=Dave|first1=Dwij|last2=Mestry|first2=Siddhesh|last3=Mhaske|first3=S.T.|date=July 2021|title=Development of flame retardant waterborne polyurethane dispersions (WPUDs) from sulfonated phosphorus-based reactive water-dispersible agents|journal=Journal of Coatings Technology and Research|publisher=American Coatings Association|volume=18|issue=4|pages=1037–1049|doi=10.1007/s11998-020-00458-6|s2cid=232370572|via=Springer10.1007/s11998-020-00458-6}} They have also found use in general textile applications such as coating nonwovens.{{Cite journal |last1=Sikdar |first1=Partha |last2=Islam |first2=Shafiqul |last3=Dhar |first3=Avik |last4=Bhat |first4=Gajanan |last5=Hinchliffe |first5=Doug |last6=Condon |first6=Brian |date=2022-07-01 |title=Barrier and mechanical properties of water-based polyurethane-coated hydroentangled cotton nonwovens |url=https://doi.org/10.1007/s11998-021-00609-3 |journal=Journal of Coatings Technology and Research |language=en |volume=19 |issue=4 |pages=1255–1267 |doi=10.1007/s11998-021-00609-3 |s2cid=247942460 |issn=1935-3804}} Leather coatings with antibacterial properties have also been synthesized using PUDs and silver nanoparticles.{{Cite journal |last1=Zhang |first1=Xiaohui |last2=Wang |first2=Wei |last3=Yu |first3=Dan |date=2018-03-01 |title=Synthesis of waterborne polyurethane–silver nanoparticle antibacterial coating for synthetic leather |url=https://doi.org/10.1007/s11998-017-9997-3 |journal=Journal of Coatings Technology and Research |language=en |volume=15 |issue=2 |pages=415–423 |doi=10.1007/s11998-017-9997-3 |s2cid=102513248 |issn=1935-3804}} On a similar theme, recent (post 2020) innovations have included producing a waterborne polyurethane that has embedded silver particles to combat COVID.{{Cite journal |last1=Dall Agnol |first1=Lucas |last2=Ornaghi |first2=Heitor Luiz |last3=Ernzen |first3=Juliano Roberto |last4=Dias |first4=Fernanda Trindade Gonzalez |last5=Bianchi |first5=Otávio |date=2023-11-01 |title=Production of a sprayable waterborne polyurethane coating with silver nanoparticles for combating SARS-CoV-2 |url=https://doi.org/10.1007/s11998-023-00788-1 |journal=Journal of Coatings Technology and Research |language=en |volume=20 |issue=6 |pages=1935–1947 |doi=10.1007/s11998-023-00788-1 |issn=1935-3804}} On a similar theme, PUD with antimicrobial properties have been developed.{{Cite journal |last1=Wrigglesworth |first1=Emma G. |last2=Tate |first2=Eldon W |date=May 2024 |title=Next-generation Antimicrobial Waterborne Polyurethane |url=https://www.coatingstech-digital.org/coatingstech/library/item/may-june_2024/4189602/ |journal=Coatings Tech (Digital) |volume=21 |issue=3 |pages=50–54}}
Weaknesses and disadvantages
Although they are perceived to have good environmental credentials{{Cite web |url=https://www.sid.ir/paper/340196/en |title=
SYNTHESIS AND CHARACTERIZATION OF ANIONIC POLYESTER-POLYURETHANE DISPERSION AS ENVIRONMENTALLY-FRIENDLY WATER BASED RESINS|access-date=2024-05-22 |website=www.sid.ir}}{{Cite journal |last1=Rengasamy |first1=Senthilkumar |last2=Mannari |first2=Vijay |date=March 2014 |title=UV-curable PUDs based on sustainable acrylated polyol: Study of their hydrophobic and oleophobic properties |url=https://doi.org/10.1016/j.porgcoat.2013.11.029 |journal=Progress in Organic Coatings |volume=77 |issue=3 |pages=557–567 |doi=10.1016/j.porgcoat.2013.11.029 |issn=0300-9440}}{{Cite journal |last1=Madbouly |first1=Samy A. |last2=Xia |first2=Ying |last3=Kessler |first3=Michael R. |date=2013-06-11 |title=Rheological Behavior of Environmentally Friendly Castor Oil-Based Waterborne Polyurethane Dispersions |url=https://pubs.acs.org/doi/10.1021/ma400200y |journal=Macromolecules |language=en |volume=46 |issue=11 |pages=4606–4616 |doi=10.1021/ma400200y |bibcode=2013MaMol..46.4606M |issn=0024-9297}}{{Cite journal |last1=Madbouly |first1=Samy A. |last2=Lendlein |first2=Andreas |date=December 2012 |title=Degradable Polyurethane/Soy Protein Shape-Memory Polymer Blends Prepared Via Environmentally-Friendly Aqueous Dispersions |url=https://onlinelibrary.wiley.com/doi/10.1002/mame.201200341 |journal=Macromolecular Materials and Engineering |language=en |volume=297 |issue=12 |pages=1213–1224 |doi=10.1002/mame.201200341 |issn=1438-7492}}{{Cite journal |last1=Jassal |first1=Manjeet |last2=Khungar |first2=Amit |last3=Bajaj |first3=Pushpa |last4=Sinha |first4=T. J. M. |date=April 2004 |title=Waterproof Breathable Polymeric Coatings Based on Polyurethanes |url=http://journals.sagepub.com/doi/10.1177/1528083704045179 |journal=Journal of Industrial Textiles |language=en |volume=33 |issue=4 |pages=269–280 |doi=10.1177/1528083704045179 |issn=1528-0837}}{{Cite journal |last1=Athawale |first1=Vilas D. |last2=Kulkarni |first2=Mona A. |date=2010-01-01 |title=Polyester polyols for waterborne polyurethanes and hybrid dispersions |url=https://www.sciencedirect.com/science/article/pii/S0300944009002124 |journal=Progress in Organic Coatings |volume=67 |issue=1 |pages=44–54 |doi=10.1016/j.porgcoat.2009.09.015 |issn=0300-9440}}{{Cite journal |last1=Xia |first1=Ying |last2=Larock |first2=Richard C. |date=2011-08-15 |title=Castor-Oil-Based Waterborne Polyurethane Dispersions Cured with an Aziridine-Based Crosslinker |url=https://onlinelibrary.wiley.com/doi/10.1002/mame.201000431 |journal=Macromolecular Materials and Engineering |language=en |volume=296 |issue=8 |pages=703–709 |doi=10.1002/mame.201000431 |issn=1438-7492}}{{Cite journal |last1=Bayat |first1=Parisa |last2=Khorasani |first2=Manouchehr |date=2021-04-01 |title=Synthesis and characterization of transparent 1-package PUD based on castor oil and polyethylene glycol |url=https://www.sciencedirect.com/science/article/pii/S0300944021000187 |journal=Progress in Organic Coatings |volume=153 |pages=106148 |doi=10.1016/j.porgcoat.2021.106148 |issn=0300-9440}}{{Cite journal |last1=Liang |first1=Haiyan |last2=Wang |first2=Shanwen |last3=He |first3=Heng |last4=Wang |first4=Mengqi |last5=Liu |first5=Lingxiao |last6=Lu |first6=Jingyi |last7=Zhang |first7=Yi |last8=Zhang |first8=Chaoqun |date=2018-10-15 |title=Aqueous anionic polyurethane dispersions from castor oil |url=https://www.sciencedirect.com/science/article/pii/S0926669018304989 |journal=Industrial Crops and Products |volume=122 |pages=182–189 |doi=10.1016/j.indcrop.2018.05.079 |issn=0926-6690}}{{Cite journal |last1=Mishra |first1=Vikash |last2=Mohanty |first2=Ishan |last3=Patel |first3=Mayank R. |last4=Patel |first4=Kalpesh I. |date=2015-08-18 |title=Development of Green Waterborne UV-Curable Castor Oil-Based Urethane Acrylate Coatings: Preparation and Property Analysis |url=http://www.tandfonline.com/doi/full/10.1080/1023666X.2015.1050852 |journal=International Journal of Polymer Analysis and Characterization |language=en |volume=20 |issue=6 |pages=504–513 |doi=10.1080/1023666X.2015.1050852 |issn=1023-666X}}{{Cite journal |last1=Lu |first1=Yongshang |last2=Larock |first2=Richard C. |date=2010-09-01 |title=Soybean oil-based, aqueous cationic polyurethane dispersions: Synthesis and properties |url=https://www.sciencedirect.com/science/article/pii/S0300944010001268 |journal=Progress in Organic Coatings |volume=69 |issue=1 |pages=31–37 |doi=10.1016/j.porgcoat.2010.04.024 |issn=0300-9440}}{{Cite journal |last1=Luo |first1=Yong-Shen |last2=Lee |first2=Da-Kong |last3=Zeng |first3=Wun-Syu |last4=Rwei |first4=Syang-Peng |date=2022-11-02 |title=Synthesis and properties of biomass polyether diols based polyurethane dispersions by a solvent-free process |url=https://doi.org/10.1007/s10965-022-03338-2 |journal=Journal of Polymer Research |language=en |volume=29 |issue=11 |pages=492 |doi=10.1007/s10965-022-03338-2 |issn=1572-8935}}{{Citation |last1=Pradhan |first1=Sukanya |title=Waterborne Polyurethanes: Chemistries and Applications |date=2023-11-05 |work=ACS Symposium Series |volume=1453 |pages=15–30 |editor-last=Gupta |editor-first=Ram K. |url=https://pubs.acs.org/doi/abs/10.1021/bk-2023-1453.ch002 |access-date=2024-05-22 |place=Washington, DC |publisher=American Chemical Society |language=en |doi=10.1021/bk-2023-1453.ch002 |isbn=978-0-8412-9691-6 |last2=Mohanty |first2=Smita}} waterborne polyurethane dispersions tend to suffer from lower mechanical strength than other resins. The use of polycarbonate based polyols in the synthesis can help overcome this weakness.{{Cite journal |last1=Ma |first1=Le |last2=Song |first2=Lina |last3=Wang |first3=Heng |last4=Fan |first4=Leiqiao |last5=Liu |first5=Baohua |date=2018-09-01 |title=Synthesis and characterization of poly(propylene carbonate) glycol-based waterborne polyurethane with a high solid content |url=https://www.sciencedirect.com/science/article/pii/S0300944017307580 |journal=Progress in Organic Coatings |volume=122 |pages=38–44 |doi=10.1016/j.porgcoat.2018.05.003 |issn=0300-9440}} The wear and corrosion resistance is also not as good and hence they are often hybridized.{{Cite journal|last=Li, Guo & Qiu|date=2016|title=Synthesis of Waterborne Polyurethane Containing Alkoxysilane Side Groups and the Properties of the Hybrid Coating Films|journal=Applied Surface Science|volume=377|pages=66–74|doi=10.1016/j.apsusc.2016.03.166|bibcode=2016ApSS..377...66L }}{{Cite journal|last=Liu, Hao and Qin|date=2021|title=In situ preparation and properties of waterborne polyurethane/edge-isocyanated hexagonal boron nitride composite dispersions|journal=Journal of Coatings Technology & Research|volume=18|issue=1|pages=117–127|doi=10.1007/s11998-020-00385-6|s2cid=222233654|issn=1547-0091}} Other strategies used to overcome some of the weaknesses include molecular design and mixing/compounding with inorganic rather than polymeric materials.{{Cite journal|author1=Kale, Manoj B. |author2=Divakaran, Nidhin |author3=Mubarak, Suhail |author4=Dhamodharan, Duraisami |author5=Senthil, T. |author6=Wu, Lixin |date=2020|title=Waterborne Polyurethane Composite Reinforced with Amine Intercalated Alpha-Zirconium Phosphate-Study of Thermal and Mechanical Properties|journal=Polymer|volume=186|doi=10.1016/j.polymer.2019.122008|s2cid=210234416}} The use of an anionic or cationic center or indeed a hydrophilic non-ionic manufacturing technique tends to result in a permanent inbuilt water resistance weakness. Research is being conducted and techniques developed to combat this weakness.{{Cite journal|last1=Xu|first1=Liangfeng|date=July 2021|title=CO2 triggered hydrophobic/hydrophilic switchable waterborne polyurethane-acrylate with simultaneously improved water resistance and mechanical properties|journal=Journal of Coatings Technology and Research|publisher=American Coatings Association|volume=18|issue=4|pages=989–998|doi=10.1007/s11998-021-00476-y|s2cid=233176697|issn=1547-0091}} Simple blending has also been employed. This has the advantage in that if no new molecule has been formed but merely blending with existing registered raw materials, then that is a way around the work required to get registration of the material under various country regimes such as REACH in Europe and TSCA in the United States. Because of the surface tension of water being so high, pinholes and other problems of air-entrainment tend to be more common and need special additives to combat.{{Cite web|title=CoatingsTech - March 2021 - page32|url=https://www.coatingstech-digital.org/coatingstech/march_2021?pg=32|access-date=2021-03-04|website=www.coatingstech-digital.org|language=en}} They also tend not to be manufactured with biobased polyols because vegetable based polyols don't have performance enhancing functional groups. Modification is possible to achieve this and enable even greener versions.{{Cite web|title=Biobased Polyol with self-crosslinking functionality|url=https://www.coatingstech-digital.org/coatingstech/january_2022?pg=32|page=32|access-date=2022-01-20|website=www.coatingstech-digital.org|language=en}}
Drying, curing and cross-linking is also not usually as good and hence research is proceeding in the area of post crosslinking to improve these features.{{Cite journal |last1=Zhang |first1=Shengwen |last2=Chen |first2=Jianfeng |last3=Han |first3=Dan |last4=Feng |first4=Yongqi |last5=Shen |first5=Chen |last6=Chang |first6=Chen |last7=Song |first7=Zhilin |last8=Zhao |first8=Jie |date=2015-05-01 |title=Effect of polyether soft segments on structure and properties of waterborne UV-curable polyurethane nanocomposites |url=https://doi.org/10.1007/s11998-014-9654-z |journal=Journal of Coatings Technology and Research |language=en |volume=12 |issue=3 |pages=563–569 |doi=10.1007/s11998-014-9654-z |issn=1935-3804 |access-date=2023-03-08 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314203218/https://link.springer.com/article/10.1007/s11998-014-9654-z |url-status=live }}{{Cite journal |last1=Bai |first1=Chenyan |last2=Zhang |first2=Xingyuan |last3=Dai |first3=Jiabing |last4=Wang |first4=Jinhua |date=2008-06-01 |title=Synthesis of UV crosslinkable waterborne siloxane–polyurethane dispersion PDMS-PEDA-PU and the properties of the films |url=https://doi.org/10.1007/s11998-007-9062-8 |journal=Journal of Coatings Technology and Research |language=en |volume=5 |issue=2 |pages=251–257 |doi=10.1007/s11998-007-9062-8 |issn=1935-3804 |access-date=2023-03-14 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202635/https://link.springer.com/article/10.1007/s11998-007-9062-8 |url-status=live }}{{Cite journal |last=Coogan |first=Richard G |date=1997-12-01 |title=Post-crosslinking of water-borne urethanes |url=https://www.sciencedirect.com/science/article/pii/S0300944097000106 |journal=Progress in Organic Coatings |language=en |volume=32 |issue=1 |pages=51–63 |doi=10.1016/S0300-9440(97)00010-6 |issn=0300-9440 |access-date=2023-03-09 |archive-date=2023-03-09 |archive-url=https://web.archive.org/web/20230309155510/https://www.sciencedirect.com/science/article/pii/S0300944097000106 |url-status=live }}{{Cite journal |last1=Wen |first1=Xiufang |last2=Mi |first2=Ruilian |last3=Huang |first3=Ying |last4=Cheng |first4=Jiang |last5=Pi |first5=Pihui |last6=Yang |first6=Zhuoru |date=2010-05-01 |title=Crosslinked polyurethane–epoxy hybrid emulsion with core–shell structure |url=https://doi.org/10.1007/s11998-009-9196-y |journal=Journal of Coatings Technology and Research |language=en |volume=7 |issue=3 |pages=373–381 |doi=10.1007/s11998-009-9196-y |issn=1935-3804 |access-date=2023-03-09 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202620/https://link.springer.com/article/10.1007/s11998-009-9196-y |url-status=live }}{{Cite journal |last1=Zhu |first1=Yun |last2=Hu |first2=Chun Pu |date=2011-05-01 |title=Preparation and characterization of waterborne polyurethane-urea composed of C9-diol-based polyester polyol |url=https://doi.org/10.1007/s11998-010-9306-x |journal=Journal of Coatings Technology and Research |language=en |volume=8 |issue=3 |pages=419–425 |doi=10.1007/s11998-010-9306-x |issn=1935-3804 |access-date=2023-03-09 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202618/https://link.springer.com/article/10.1007/s11998-010-9306-x |url-status=live }}{{Cite journal |last1=Kim |first1=B. K. |date=1996-07-01 |title=Aqueous polyurethane dispersions |url=https://doi.org/10.1007/BF00653056 |journal=Colloid and Polymer Science |language=en |volume=274 |issue=7 |pages=599–611 |doi=10.1007/BF00653056 |issn=1435-1536 |access-date=2023-03-09 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202628/https://link.springer.com/article/10.1007/BF00653056 |url-status=live }}{{Cite journal |last1=Yin |first1=Wenhua |last2=Zeng |first2=Xingrong |last3=Li |first3=Hongqiang |last4=Hou |first4=Youjun |last5=Gao |first5=Qiongzhi |date=2011-10-01 |title=Synthesis, photopolymerization kinetics, and thermal properties of UV-curable waterborne hyperbranched polyurethane acrylate dispersions |url=https://doi.org/10.1007/s11998-011-9338-x |journal=Journal of Coatings Technology and Research |language=en |volume=8 |issue=5 |pages=577–584 |doi=10.1007/s11998-011-9338-x |issn=1935-3804 |access-date=2023-03-09 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202630/https://link.springer.com/article/10.1007/s11998-011-9338-x |url-status=live }}{{Cite journal |last1=Labukas |first1=Joseph P. |last2=Escarsega |first2=John A. |last3=Crawford |first3=Dawn M. |date=2014-03-01 |title=Accelerated drying of water-dispersible polyurethane blends |url=https://doi.org/10.1007/s11998-013-9536-9 |journal=Journal of Coatings Technology and Research |language=en |volume=11 |issue=2 |pages=217–229 |doi=10.1007/s11998-013-9536-9 |issn=1935-3804 |access-date=2023-03-08 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202624/https://link.springer.com/article/10.1007/s11998-013-9536-9 |url-status=live }}{{Cite journal |last1=van Tent |first1=Abraham |last2=Zohrehvand |first2=Shiva |last3=te Nijenhuis |first3=Klaas |date=2014-03-01 |title=Characterization of film formation in waterborne polymer lattices: a focus on turbidimetry |url=https://doi.org/10.1007/s11998-013-9491-5 |journal=Journal of Coatings Technology and Research |language=en |volume=11 |issue=2 |pages=159–167 |doi=10.1007/s11998-013-9491-5 |issn=1935-3804 |access-date=2023-03-08 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202624/https://link.springer.com/article/10.1007/s11998-013-9491-5 |url-status=live }}{{Cite journal |last1=Lin |first1=Xufeng |last2=Zhang |first2=Shouyi |last3=Qian |first3=Jun |date=2014-05-01 |title=Synthesis and properties of a novel UV-curable waterborne hyperbranched polyurethane |journal=Journal of Coatings Technology and Research |language=en |volume=11 |issue=3 |pages=319–328 |doi=10.1007/s11998-013-9520-4 |issn=1935-3804 |doi-access=free }}{{Cite journal |last1=Suresh |first1=Kattimuttathu I. |last2=Harikrishnan |first2=M. G. |date=2014-07-01 |title=Effect of cardanol diol on the synthesis, characterization, and film properties of aqueous polyurethane dispersions |url=https://doi.org/10.1007/s11998-014-9571-1 |journal=Journal of Coatings Technology and Research |language=en |volume=11 |issue=4 |pages=619–629 |doi=10.1007/s11998-014-9571-1 |issn=1935-3804 |access-date=2023-03-08 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202638/https://link.springer.com/article/10.1007/s11998-014-9571-1 |url-status=live }}{{Cite journal |last1=Ma |first1=Guozhang |last2=Guan |first2=Taotao |last3=Hou |first3=Caiying |last4=Wu |first4=Jianbing |last5=Wang |first5=Gang |last6=Ji |first6=Xuan |last7=Wang |first7=Baojun |date=2015-05-01 |title=Preparation, properties and application of waterborne hydroxyl-functional polyurethane/acrylic emulsions in two-component coatings |url=https://doi.org/10.1007/s11998-014-9647-y |journal=Journal of Coatings Technology and Research |language=en |volume=12 |issue=3 |pages=505–512 |doi=10.1007/s11998-014-9647-y |issn=1935-3804 |access-date=2023-03-08 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314203207/https://link.springer.com/article/10.1007/s11998-014-9647-y |url-status=live }}
Hybrids
The disadvantages of PUDs are being improved by research.{{Cite journal |last1=Lin |first1=Xufeng |last2=Zhang |first2=Shouyi |last3=Qian |first3=Jun |date=2014-05-01 |title=Synthesis and properties of a novel UV-curable waterborne hyperbranched polyurethane |journal=Journal of Coatings Technology and Research |language=en |volume=11 |issue=3 |pages=319–328 |doi=10.1007/s11998-013-9520-4 |issn=1935-3804 |doi-access=free }}{{Cite journal |last1=García-Pacios |first1=Vanesa |last2=Colera |first2=Manuel |last3=Iwata |first3=Yoshiro |last4=Martín-Martínez |first4=José Miguel |date=2013-12-01 |title=Incidence of the polyol nature in waterborne polyurethane dispersions on their performance as coatings on stainless steel |url=https://www.sciencedirect.com/science/article/pii/S0300944013001264 |journal=Progress in Organic Coatings |series=Coatings Science International 2012 |language=en |volume=76 |issue=12 |pages=1726–1729 |doi=10.1016/j.porgcoat.2013.05.007 |issn=0300-9440 |access-date=2023-03-09 |archive-date=2023-03-09 |archive-url=https://web.archive.org/web/20230309151249/https://www.sciencedirect.com/science/article/pii/S0300944013001264 |url-status=live }}{{Cite journal |last1=Noble |first1=Karl-Ludwig |date=1997-12-01 |title=Waterborne polyurethanes |url=https://www.sciencedirect.com/science/article/pii/S0300944097000714 |journal=Progress in Organic Coatings |language=en |volume=32 |issue=1 |pages=131–136 |doi=10.1016/S0300-9440(97)00071-4 |issn=0300-9440 |access-date=2023-03-09 |archive-date=2023-03-09 |archive-url=https://web.archive.org/web/20230309151129/https://www.sciencedirect.com/science/article/pii/S0300944097000714 |url-status=live }}{{Cite journal |last1=Suresh |first1=Kattimuttathu I. |last2=Harikrishnan |first2=M. G. |date=2014-07-01 |title=Effect of cardanol diol on the synthesis, characterization, and film properties of aqueous polyurethane dispersions |url=https://doi.org/10.1007/s11998-014-9571-1 |journal=Journal of Coatings Technology and Research |language=en |volume=11 |issue=4 |pages=619–629 |doi=10.1007/s11998-014-9571-1 |issn=1935-3804 |access-date=2023-03-08 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202638/https://link.springer.com/article/10.1007/s11998-014-9571-1 |url-status=live }} Hybridization using other materials and techniques is one such area. PUDs that are waterborne and UV curable are being intensely researched with well over 100 research papers produced in the 2000-2020 time period.{{Cite journal |last1=Yuan |first1=Caideng |last2=Wang |first2=Mengyao |last3=Li |first3=Haitao |last4=Wang |first4=Zhongwei |date=2017-09-10 |title=Preparation and properties of UV-curable waterborne polyurethane-acrylate emulsion |url=https://onlinelibrary.wiley.com/doi/10.1002/app.45208 |journal=Journal of Applied Polymer Science |language=en |volume=134 |issue=34 |pages=45208 |doi=10.1002/app.45208}}{{Cite journal |last1=Song |first1=Sam Cha |last2=Kim |first2=Suk Joon |last3=Park |first3=Kyung-Kyu |last4=Oh |first4=Joong-Geul |last5=Bae |first5=Seong-Guk |last6=Noh |first6=Geon Ho |last7=Lee |first7=Won-Ki |date=2017-12-12 |title=Synthesis and properties of waterborne UV-curable polyurethane acrylates using functional isocyanate |url=https://doi.org/10.1080/15421406.2018.1450824 |journal=Molecular Crystals and Liquid Crystals |volume=659 |issue=1 |pages=40–45 |doi=10.1080/15421406.2018.1450824 |bibcode=2017MCLC..659...40S |s2cid=102697178 |issn=1542-1406}}{{Cite journal |last1=Dall Agnol |first1=Lucas |last2=Dias |first2=Fernanda Trindade Gonzalez |last3=Ornaghi |first3=Heitor Luiz |last4=Sangermano |first4=Marco |last5=Bianchi |first5=Otávio |date=2021-05-01 |title=UV-curable waterborne polyurethane coatings: A state-of-the-art and recent advances review |url=https://www.sciencedirect.com/science/article/pii/S0300944021000266 |journal=Progress in Organic Coatings |volume=154 |pages=106156 |doi=10.1016/j.porgcoat.2021.106156 |issn=0300-9440}}{{Cite journal |last1=Xu |first1=Heping |last2=Qiu |first2=Fengxian |last3=Wang |first3=Yingying |last4=Wu |first4=Wenling |last5=Yang |first5=Dongya |last6=Guo |first6=Qing |date=2012-01-01 |title=UV-curable waterborne polyurethane-acrylate: preparation, characterization and properties |url=https://www.sciencedirect.com/science/article/pii/S0300944011002505 |journal=Progress in Organic Coatings |language=en |volume=73 |issue=1 |pages=47–53 |doi=10.1016/j.porgcoat.2011.08.019 |issn=0300-9440}}{{Cite journal |last1=Llorente |first1=O. |last2=Fernández-Berridi |first2=M. J. |last3=González |first3=A. |last4=Irusta |first4=L. |date=2016-10-01 |title=Study of the crosslinking process of waterborne UV curable polyurethane acrylates |url=https://www.sciencedirect.com/science/article/pii/S0300944016302843 |journal=Progress in Organic Coatings |language=en |volume=99 |pages=437–442 |doi=10.1016/j.porgcoat.2016.06.020 |issn=0300-9440}}{{Cite journal |last1=Dall Agnol |first1=Lucas |last2=Dias |first2=Fernanda Trindade Gonzalez |last3=Ornaghi |first3=Heitor Luiz |last4=Sangermano |first4=Marco |last5=Bianchi |first5=Otávio |date=2021-05-01 |title=UV-curable waterborne polyurethane coatings: A state-of-the-art and recent advances review |url=https://www.sciencedirect.com/science/article/pii/S0300944021000266 |journal=Progress in Organic Coatings |language=en |volume=154 |pages=106156 |doi=10.1016/j.porgcoat.2021.106156 |s2cid=233544254 |issn=0300-9440}} Waterborne PUD- Acrylates based on epoxidized soybean oil that is also UV curable have been produced and are feasible.{{Cite journal |last1=Li |first1=Xiu |last2=Wang |first2=Di |last3=Zhao |first3=Longying |last4=Hou |first4=Xingzhou |last5=Liu |first5=Li |last6=Feng |first6=Bin |last7=Li |first7=Mengxin |last8=Zheng |first8=Pai |last9=Zhao |first9=Xuan |last10=Wei |first10=Shuangying |date=2021-02-01 |title=UV LED curable epoxy soybean-oil-based waterborne PUA resin for wood coatings |journal=Progress in Organic Coatings |language=en |volume=151 |pages=105942 |doi=10.1016/j.porgcoat.2020.105942 |s2cid=225111943 |issn=0300-9440|doi-access=free }} The nature of the acrylate affects the properties.{{Cite journal |last1=Ahmed |first1=Aziz |last2=Sarkar |first2=Preetom |last3=Ahmad |first3=Imtiaz |last4=Das |first4=Neeladri |last5=Bhowmick |first5=Anil K. |date=2015-01-14 |title=Influence of the Nature of Acrylates on the Reactivity, Structure, and Properties of Polyurethane Acrylates |url=https://pubs.acs.org/doi/10.1021/ie502953u |journal=Industrial & Engineering Chemistry Research |language=en |volume=54 |issue=1 |pages=47–54 |doi=10.1021/ie502953u |issn=0888-5885}} One use of hybrids is in textile finishes.{{Cite journal |last1=Sultan |first1=Misbah |last2=Islam |first2=Atif |last3=Gull |first3=Nafisa |last4=Bhatti |first4=Haq Nawaz |last5=Safa |first5=Yusra |date=2015-03-20 |title=Structural variation in soft segment of waterborne polyurethane acrylate nanoemulsions |url=https://onlinelibrary.wiley.com/doi/10.1002/app.41706 |journal=Journal of Applied Polymer Science |language=en |volume=132 |issue=12 |doi=10.1002/app.41706 |issn=0021-8995}}
As ionic centers are introduced with waterborne PUDs, the water resistance and uptake in the final film has been studied extensively. The nature of the polyol and the level of COOH groups and hydrophobic modification with other moieties can improve this property. Polyester polyols give the biggest improvements.{{Cite journal |last1=Bai |first1=Chen Yan |last2=Zhang |first2=Xing Yuan |last3=Dai |first3=Jia Bing |last4=Zhang |first4=Chu Yin |date=2007-07-02 |title=Water resistance of the membranes for UV curable waterborne polyurethane dispersions |url=https://www.sciencedirect.com/science/article/pii/S0300944007001075 |journal=Progress in Organic Coatings |language=en |volume=59 |issue=4 |pages=331–336 |doi=10.1016/j.porgcoat.2007.05.003 |issn=0300-9440}} Polycarbonate polyols also enhance properties,{{Cite journal |last1=Hwang |first1=Hyeon-Deuk |last2=Park |first2=Cho-Hee |last3=Moon |first3=Je-Ik |last4=Kim |first4=Hyun-Joong |last5=Masubuchi |first5=Tetsuo |date=2011-12-01 |title=UV-curing behavior and physical properties of waterborne UV-curable polycarbonate-based polyurethane dispersion |url=https://www.sciencedirect.com/science/article/pii/S030094401100227X |journal=Progress in Organic Coatings |language=en |volume=72 |issue=4 |pages=663–675 |doi=10.1016/j.porgcoat.2011.07.009 |issn=0300-9440}} especially if the polycarbonate is also fluorinated.{{Cite journal |last1=Hwang |first1=Hyeon-Deuk |last2=Kim |first2=Hyun-Joong |date=2011-10-15 |title=UV-curable low surface energy fluorinated polycarbonate-based polyurethane dispersion |url=https://www.sciencedirect.com/science/article/pii/S0021979711007788 |journal=Journal of Colloid and Interface Science |language=en |volume=362 |issue=2 |pages=274–284 |doi=10.1016/j.jcis.2011.06.044 |pmid=21788027 |bibcode=2011JCIS..362..274H |issn=0021-9797}} Reinforcing PUDs with nanomaterials also improves properties,{{Cite journal |last1=Sangermano |first1=M. |last2=Lak |first2=N. |last3=Malucelli |first3=G. |last4=Samakande |first4=A. |last5=Sanderson |first5=R. D. |date=2008-01-01 |title=UV-curing and characterization of polymer–clay nanocoatings by dispersion of acrylate-funtionalized organoclays |url=https://www.sciencedirect.com/science/article/pii/S0300944007002007 |journal=Progress in Organic Coatings |language=en |volume=61 |issue=1 |pages=89–94 |doi=10.1016/j.porgcoat.2007.09.009 |issn=0300-9440}}{{Cite journal |last1=Choi |first1=H. Y. |last2=Bae |first2=C. Y. |last3=Kim |first3=B. K. |date=2010-08-01 |title=Nanoclay reinforced UV curable waterborne polyurethane hybrids |url=https://www.sciencedirect.com/science/article/pii/S0300944010000937 |journal=Progress in Organic Coatings |language=en |volume=68 |issue=4 |pages=356–362 |doi=10.1016/j.porgcoat.2010.03.015 |issn=0300-9440}} as does silicone modification.{{Cite journal |last1=Zhang |first1=Dinglun |last2=Liu |first2=Jin |last3=Li |first3=Zhen |last4=Shen |first4=Yun |last5=Wang |first5=Ping |last6=Wang |first6=Di |last7=Wang |first7=Xianbiao |last8=Hu |first8=Xianhai |date=2021-11-01 |title=Preparation and properties of UV-curable waterborne silicon-containing polyurethane acrylate emulsion |url=https://www.sciencedirect.com/science/article/pii/S030094402100374X |journal=Progress in Organic Coatings |language=en |volume=160 |pages=106503 |doi=10.1016/j.porgcoat.2021.106503 |s2cid=240504048 |issn=0300-9440}}{{Cite journal |last1=Bai |first1=Chenyan |last2=Zhang |first2=Xingyuan |last3=Dai |first3=Jiabing |date=2007-08-01 |title=Synthesis and characterization of PDMS modified UV-curable waterborne polyurethane dispersions for soft tact layers |url=https://www.sciencedirect.com/science/article/pii/S0300944007001476 |journal=Progress in Organic Coatings |language=en |volume=60 |issue=1 |pages=63–68 |doi=10.1016/j.porgcoat.2007.07.003 |issn=0300-9440}}{{Cite journal |last1=Hong |first1=Chengqi |last2=Zhou |first2=Xing |last3=Ye |first3=Yuanchao |last4=Li |first4=Wenbo |date=2021-07-01 |title=Synthesis and characterization of UV-curable waterborne Polyurethane–acrylate modified with hydroxyl-terminated polydimethylsiloxane: UV-cured film with excellent water resistance |url=https://www.sciencedirect.com/science/article/pii/S0300944021001223 |journal=Progress in Organic Coatings |language=en |volume=156 |pages=106251 |doi=10.1016/j.porgcoat.2021.106251 |s2cid=233549036 |issn=0300-9440}}
To make PUDs more hydrophobic and water repellent and thus remove a weakness, a number of techniques have been researched. One way is to add hydroxyethyl acrylate to the polyol reacting with isocyanate. Once the PUD is made it will have terminal double bond functionality from the acrylate. This may now be copolymerized with a very hydrophobic acrylate such as stearyl acrylate using free radical techniques. This long alkyl chain introduced confers hydrophobicity.{{Cite journal |last1=Sheng |first1=Lixia |last2=Zhang |first2=Xuetong |last3=Ge |first3=Zhen |last4=Liang |first4=Zhu |last5=Liu |first5=Xiaoli |last6=Chai |first6=Chunpeng |last7=Luo |first7=Yunjun |date=2018-11-01 |title=Preparation and properties of waterborne polyurethane modified by stearyl acrylate for water repellents |url=https://doi.org/10.1007/s11998-018-0096-x |journal=Journal of Coatings Technology and Research |language=en |volume=15 |issue=6 |pages=1283–1292 |doi=10.1007/s11998-018-0096-x |s2cid=103071000 |issn=1935-3804}}
Another method of hybridization is to make a PUD that is both anionic but with a very substantial nonionic modification utilizing a polyether polyol based on ethylene oxide. In addition, a silicone diol maybe incorporated.{{Cite journal |last1=Wei |first1=Xiaoli |last2=Zhang |first2=Faxing |date=2018-11-01 |title=Preparation of an ionic/nonionic polyurethane-silicone dispersion (PUSD) with a high solid content and low viscosity using complex soft segments |url=https://doi.org/10.1007/s11998-018-0063-6 |journal=Journal of Coatings Technology and Research |language=en |volume=15 |issue=6 |pages=1229–1237 |doi=10.1007/s11998-018-0063-6 |s2cid=103148606 |issn=1935-3804}}
As epoxy resins have some outstanding properties, research using epoxy to modify PUD is taking place.{{Cite journal |last1=Xiao |first1=Yiheng |last2=Ou |first2=Wei |last3=He |first3=Zonglin |last4=Ding |first4=Zhu |last5=Ai |first5=Jiaoyan |last6=Song |first6=Lina |last7=Liu |first7=Baohua |date=2023-10-27 |title=Synthesis of poly (propylene carbonate) diol-based waterborne polyurethane modified by epoxy resin with anticorrosion properties |url=https://doi.org/10.1007/s11998-023-00823-1 |journal=Journal of Coatings Technology and Research |volume=21 |issue=1 |language=en |doi=10.1007/s11998-023-00823-1 |issn=1935-3804}}
PUDs that are based on thiol rather than hydroxyl and also modified with both acrylate as well as epoxy functionality have been produced and researched.{{Cite journal |last1=Mishra |first1=Vikash |last2=Desai |first2=Jatin |last3=Patel |first3=Kalpesh I. |date=2017-09-01 |title=High-performance waterborne UV-curable polyurethane dispersion based on thiol–acrylate/thiol–epoxy hybrid networks |url=https://doi.org/10.1007/s11998-016-9906-1 |journal=Journal of Coatings Technology and Research |language=en |volume=14 |issue=5 |pages=1069–1081 |doi=10.1007/s11998-016-9906-1 |issn=1935-3804 |access-date=2023-02-20 |archive-date=2023-03-14 |archive-url=https://web.archive.org/web/20230314202625/https://link.springer.com/article/10.1007/s11998-016-9906-1 |url-status=live }}
As PUDs are resin dispersed in water, when cast as a film and dried they are inherently high gloss. They can be designed to be matte/flat by incorporating siloxane functionality.{{Cite journal |last1=Yong |first1=Qiwen |last2=Liao |first2=Bing |last3=Ying |first3=Guo |last4=Caizhen |first4=Liang |last5=Huang |first5=Hao |last6=Pang |first6=Hao |date=2018-09-01 |title=Structure and surface properties of a novel bulk-matte waterborne polyurethane coating composite |url=https://doi.org/10.1007/s11998-017-0030-7 |journal=Journal of Coatings Technology and Research |language=en |volume=15 |issue=5 |pages=993–1002 |doi=10.1007/s11998-017-0030-7 |s2cid=140013153 |issn=1935-3804}}
Since PUDs are usually considered green and environmentally friendly, techniques being researched also include capturing carbon dioxide from the atmosphere to make the raw materials and then further synthesis.{{Cite journal |last1=Ding |first1=Zhu |last2=Chen |first2=Jiahui |last3=He |first3=Zonglin |last4=Wang |first4=Chaozhi |last5=Li |first5=Hualin |last6=Huang |first6=Zhenhong |last7=Liu |first7=Baohua |last8=Song |first8=Lina |date=2023-09-01 |title=Two-component UV-curable waterborne CO2-based polyurethane dispersion with outstanding flexibility |url=https://doi.org/10.1007/s11998-023-00763-w |journal=Journal of Coatings Technology and Research |language=en |volume=20 |issue=5 |pages=1569–1578 |doi=10.1007/s11998-023-00763-w |issn=1935-3804}}
See also
References
{{Reflist}}
External links
- [http://www.alberdingkusa.com/products/technical-data/cat2/water-based-polyurethane-dispersions-1.html Alberdink and Boley Website]
- [https://www.lubrizol.com/-/media/Site-Data/Literature/Brochures/Polyurethane-Dispersions-Product-Guide---17-72506.pdf Lubrizol website]
- [https://www.mitsuichemicals.com/take_coatings.htm Mitsui]
- [https://polyurethane.americanchemistry.com/polyurethane/Introduction-to-Polyurethanes/Applications/PUDs/ American General Info]
- [https://www.dispersions-pigments.basf.com/portal/basf/ien/dt.jsp?setCursor=1_736943 BASF]
- [https://www.perstorp.com/en/products/resins/polyurethane_dispersions Perstorp Range]
- [https://incorez.com/products/polyurethane-dispersions Incorez range]
- [https://www.halox.com/polyurethane-dispersion-pud/ Halox includes formulations]
- [http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_003b/0901b8038003b559.pdf DOW literature with overview]