Synthesis of Polyurethane Containing Siloxane Ladder Sequences in Its Backbone

Abstract

Alcoholic hydroxyl groups were introduced into poly(silsesquioxane) [PPSQ] as chain-terminating residues, and the resulting HO-telechelic PPSQ's (HO-PPSQ's) were reacted with propylene glycol (PG) and m-xylylene diisocyanate (XDI) to yield a block copolymer composed of PPSQ and polyurethane repeating units. PPSQ was obtained by the hydrolysis of phenyltrichlorosilane and subsequent condensation reaction. Fractionated portion of PPSQ with Mn = 5000 was converted to HO-PPSQ by the end-capping reaction with phenyldichlorosilane followed by the hydrosilylation with allyl alcohol. The mixture of HO-PPSQ and PG was further reacted with XDI to result the targetting (PPSQ-block-urethane) copolymer of Mn~ 11500. In the IR spectrum of the block copolymer, absorption bands of PPSQ and those assignable to urethane linkages of PG/XDI repeating units were distinguished. The results of DSC measurement also indicated that the products were not mere mixtures but the PPSQ chains were introduced by covalent bonding into the urethane block copolymer backbone. © 1995, The Society of Polymer Science, Japan. All rights reserved.