Polyurethane (PU) block copolymers were synthesized using prepared hydroxypropyl terminated polydimethylsiloxane (HTPDMS MW 990) and polyether diols (N-210) as soft segment with 4,4-diphenylmethane diisocyanate (MDI) and 1,4-butanediol. This low molecular weight polydimethylsiloxanes (PDMS) containing hydroxypropyl end-groups displayed better compatibility with PU than common PDMS. In this article, we illustrate its synthesis routes and confirmed the proposed molecular structures using NMR and infrared radiation (IR). We varied the contents of HTPDMS and N-210 in soft segments (HTPDMSN-210: 0 : 100, 20 : 80, 40 : 60, 60 : 40, 80 : 20, and 100 : 0) to synthesize a series of PDMS-PU copolymer. IR spectroscopy showed the assignment characteristic groups of each peak in copolymers and confirmed that the desired HTPDMS-PU copolymers have been prepared. The different thermal, dynamic mechanical and surface properties of the copolymers were compared by thermogravimetry, DMA, contact angle and solvent resistance. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013