Thermoreversible Polyurea

Patent Title: DYNAMIC UREA BONDS FOR POLYMERS

 Number/Link: W02016/069582

Applicant/Assignee: University of Illinois

Publication date: 6-05-2016

Gist”: Urea bonds prepared from sterically hindered amines and isocyanates

Why it is interesting: The N-C bond in urea is very stable due to conjugation of the lone electron pair of the nitrogen atom with the cabonyl group.  According to this invention, the nitrogen atom can be subsituted with a strongly hindering group such that the coplanarity, and therefore most of the conjugation, of the C-N and C=O bonds is lost. These hindered urea bonds are much less stable and can reversibly depolymerize at relatively low temperatures. Thermoreversible bonds can be useful in a number of smart materials such as self-healing-, “4D printing”- , and reprogrammable shape memory materials. In an example a shape memory material with a Tg of 53°C and a Young’s Modulus of about 2 GPa was prepared by reacting 2-(t-buylamino)ethanol (TBAE) and trimerized hexamethylene diisocyanate (THDI). The ‘permanent shape’ of the material could be re-programmed by forcing the material in a new shape for 72 hours at 60°C.

Polurethane-urea with thermoreverisble urea bonds

Poly(urethane-urea) with thermoreverisble urea bonds

Hydrophobic Coatings from BO Polyols

Title: POLYURETHANE ENCAPSULATE

 Number/Link: WO2014/176390

Applicant/Assignee: Dow

Publication date: 30-10-2014

Gist”: Use of polybutyleneoxide polyols for hydrophobic encapsulants.

Why it is interesting: The encapsulation of water soluble compounds for controlled release, like e.g. plant nutrients and fertilizers, requires a relatively hydrophobic coating.  Often this is accomplished with polyurethane coatings to which hydrophic compounds are added such as castor oil derivatives. These additives can however have a deleterious effect on other coating properties.  According to this invention encapsulation coatings with good mechanical properties and improved water absorption and water vapour transmission properties can be prepared from polybutyleneoxide triols and polymeric MDI without the need for other additives.

Butylene oxide

Butylene oxide

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