Synthesis and Thermal behavior of poly (ethylene oxide) poly (N-substituted urethane)

Waterborne polyurethane as a new polymer dispersion was synthesized by using relatively hydrophilic polyols. Poly (N-Substituted urethane)s with different molecular weight of polyethylene glycol monomethyl ether side chain were synthesized form sodium hydride, chlorinated polyethylene glycol monomethyl ether (PEGMME), and polyether and polyester urethane containing poly tertahydrofuran or polycaprolactone/ Toluene diisocyanate and 1, 4- butanediol. The chemical structures were characterized with FTIR and FT1HNMR. To investigate the effect of different MW of N-substituted side chain on the morphology, thermal property and particle size distribution of the final product, we used differential scanning calorimetry and laser light scattering. N-Substitution of polyurethane had significant influences on thermal properties and solubility of the resulting material.Tg of the N-substituted urethane decreases with N- substitution and gradually increases with increasing molecular weight of the substituted side chain. This is more obvious in higher molecular weight. The particle size of final water borne PU emulsion also decreases with increasing MW of PEGMME. The decreasing particle size may be due to increased chain flexibility and or hydrophilicity of N-substituted polyurethanes.