Liquid Crystalline Polyurethane Elastomers

Patent Title: LIQUID CRYSTALLINE POLYURETHANE ELASTOMER AND METHOD FOR PRODUCING SAME

 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

Polyurethane Elastomer with High Dielectric Constant

Patent Title: DIPOLE-MODIFIED POLYURETHANE, METHOD FOR PRODUCING SAME, AND USE THEREOF IN THE PRODUCTION OF CAST ELECTROACTIVE POLYURETHANE-BASED ELASTOMER FILMS

 Number/Link: WO2016102320  (German)

Applicant/Assignee: Covestro

Publication date: 30-06-2016

Gist”: A molecule with high dipole moment is incorparted in the PU backbone

Why it is interesting: According to this invention a polyurethane with an increased dielectric constant can be prepared by first reacting an isocyanate (f>2)with a hydroxyl-functional dipole.  This ‘dipole-modified’ isocyanate is then used in a (preferred) amount of 5-10% on the rest of the isocyanate of an elastomer formulation.  The dipole is of the form HO-R-D-X-A, where  D is an electron donor, A is an electron acceptor and X is a residue with a delocalized electron system.  In an example N-2-hydroxyethyl-N-methyl-4-nitroanilin is reacted with a biuret based on HDI to make the ‘dipole-modified’ isocyanate. Polyurethane elastomer films with high dielectric constant can be used as electromechanical transducers in sensors, actuators, artifical muscle etc..

N-2-Hydroxyethyl-N-Methyl-4-Nitroanilin

N-2-Hydroxyethyl-N-Methyl-4-Nitroanilin

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