02179nas a2200241   4500008004100000022001400041245011500055210006900170260006800239300001400307490000700321520131700328653001001645653002401655653001801679653002101697653001801718653002201736653001801758100001401776700001901790856012801809       2008                        eng d  a0887-624X00aSolvent-free and nonisocyanate melt transurethane reaction for aliphatic polyurethanes and mechanistic aspects0 aSolventfree and nonisocyanate melt transurethane reaction for al  a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcAPR  a2445-24580 v463 a<p>A novel melt transurethane polycondensation route for polyurethanes under solvent-free and nonisocyanate condition was developed for soluble and thermally stable aliphatic or aromatic polyurethanes. The new transurethane process was investigated for A + 13, A-A + B, and A-A + B-B (A-urethane and B-hydroxyl) type condensation reactions, and also monomers bearing primary and secondary urethane or hydroxyl functionalities. The transurethane process was confirmed by H-1 and C-13 NMR, and molecular weight of the polymers were obtained as M-n = 10-15 X 10(3) and M-w = 15-45 X 10(3) g/mol. The mechanistic aspects of the melt transurethane process and role of the catalyst were investigated using model reactions, H-1 NMR, and MALDI-TOF-MS. The model reactions indicated the occurrence of 97% reaction in the presence of catalyst, whereas its absence gave only less than 2% of the product. The polymer samples were subjected for end-group analysis using MALDI-TOF-MS, which confirms the Ti-catalyst mediated nonisocyanate pathway in the melt transurethane process. Almost all the polyurethanes were stable up to 280 degrees C, and the T-g of the polyurethanes can be easily fine-tuned from -30 to 120 degrees C by using appropriate diols in the melt transurethane process. (C) 2008 Wiley Periodicals, Inc.</p>10aMALDI10amelt polymerization10anonisocyanate10aPolycondensation10apolyurethanes10athermal stability10atransurethane1 aDeepa, P.1 aJayakannan, M.  uhttps://library.ncl.res.in/content/solvent-free-and-nonisocyanate-melt-transurethane-reaction-aliphatic-polyurethanes-and-0