Liquid Crystalline Polyurethane Elastomers


 Number/Link: US 2016/0376396

Applicant/Assignee: Toyo Tire & Rubber

Publication date: 29-dec-2016

Gist”: Specific mesogenic diols are used together with high MW polyols and high functionality isocyanate

Why it is interesting: The invention is about thermotropic liquid crystalline PU elastomers, where the liquid crystalline (LC) phase is formed at relatively low temperatures (e.g. near room temperature). This is accomplished by preventing the mesogen to crystallize, such that it shows no melting point between its Tg and Ti (LC phase -to- isotropic phase transition temperature). This, in turn, is accomplished by using a high molecular weight polyol together with a high functionality isocyanate and a mesogenic diol of the structure shown below where Y represents -N=N-, -CO-, -CO-O- or -CH=N- and X represents a C3 to C20 alkylene.  Under stress the elastomer extends in the orientation direction by increasing the LC content and shrinks by reducing LC content.  It can therefore be used as a temperature-controlled actuator.

General structure of the mesogenic diol of the invention

General structure of the mesogenic diol of the invention

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