| abstract |
Novel organopolysiloxane/polyurethane block copolymers which are thermoplastic elastomers and which possess good thermomechanical properties, are comprised of the following recurring units (A) and (B): ##STR1## wherein Z is a divalent radical which comprises a polysiloxane block and has the formula: ##STR2## in which Y and Y' are each a divalent radical having one of the formulae: ##STR3## wherein T and T' comprise the divalent or trivalent residue having from 1 to 20 carbon atoms of an unsaturated isocyanate or alcohol having one of the formulae: n n OCN--T--CR.sub.1 ═CR.sub.2 R.sub.3 n n n HO--T--CR.sub.1 ═CR.sub.2 R.sub.3 n n ##STR4## or an oxygen, sulfur, silicon, nitrogen, ester or amide interrupted such T or T' residue, and further wherein R 1 , R 2 and R 3 are each hydrogen, alkyl or aryl, with the proviso that two of the radicals R 1 and R 2 may together form a single alkylene radical; each R is an alkyl or halogenoalkyl radical having from 1 to 5 carbon atoms and containing from 1 to 7 chlorine and/or fluorine substituents, cycloalkyl or halogenocycloalkyl radical having from 3 to 8 carbon atoms and containing from 1 to 4 chlorine and/or fluorine substituents, aryl, alkylaryl or halogenoaryl radical having from 6 to 8 carbon atoms and containing from 1 to 4 chlorine and/or fluorine substituents, or a cyanoalkyl radical having from 3 to 4 carbon atoms; n is a number of at least 10; G 1 and G 2 are each divalent hydrocarbon radicals having from 2 to 20 carbon atoms, or two such hydrocarbon radicals joined together by a direct valence bond or through an oxygen atom or alkylene or alkylidene bridge having from 1 to 4 carbon atoms; m is a number ranging from 1 to 20; and a is a number which is either zero or 1. |