Title: SELF-HEALING POLYURETHANES

 Number/Link: WO2015/067833 (Spanish)

Applicant/Assignee: Fundacion Gaiker

Publication date: 14-05-2015

“Gist”: Self-healing polyurethanes coatings can be prepared using dihydroxy coumarin derivatives

Why it is interesting: Self-healing polymers have been made before using e.g. microencapsulated ‘healing agents’ or supramolecular chemistry such as hydrogen-bond formation.  This patent application relates to polyurethanes having photochemical self-healing properties, which, in contrast to previous systems, have the advantage of allowing for multiple recoveries and for (potentially) being transparent. The self-repairing PU systems are based on the photodimerization and photocleavage reactions of coumarine-derivatives as shown in the scheme below.  Dihydroxy derivatives of coumarine can be built into PU coatings sytems. Damaged coatings can then be radiated with light of a wavelength of (pref.) 254nm to cleave coumarin dimers present, followed by radiation of about 340nm to (re-)form the dimers and repair the coating.

Photodimerization and -cleavage of coumarine derivatives