Studies on novel thermally stable segmented polyurethanes based on thiourea-derivative diols

Novel thermoplastic segmented poly(urethane-thiourea)s (PURs) were synthesized via one-step polymerization from aromatic diols containing sulfur (thiourea linkage) in the main-chain, including terephthaloyl bis (3-(2-hydroxopyridyl) thiourea) (TBHPT) and terephthaloyl bis (3-(5-naphtholyl) thiourea) (TBNT), along with 1,4-phenylene diisocyanate (PDI) as hard segment and 20, 50 and 80 mol% polyethylene glycol (PEG) as a soft segment. The prepared chain extenders and polymers were characterized by conventional methods, and physical properties such as eta(inh), solubility, thermal stability and thermal behavior were studied. Easily processable PURs with excellent thermal stability were obtained by incorporating 20 mol% PEG in the soft segment. Thermogravimetric analysis indicated that poly (urethane-thiourea)s were fairly stable above 500 degrees C and own high glass transition temperatures about 263-266 degrees C. These polymers also showed partially crystalline structures. Ultimately, weight average molecular weights (M-w) of PURs were up to 10(9) x 10(3). Compared to typical polyurethanes. PURs exhibited better thermal stability and T-g's owing to rigid hard segment structure. (C) 2010 Elsevier Ltd. All rights reserved.