Synthesis and characterization of calcium containing poly(urethane-ether)s

Calcium containing poly(urethane-ether)s (PUEs) were synthesized by the reaction of hexamethylene diisocyanate or toluylene 2,4-diisocyanate (HMDI or TDI) with a mixture of calcium salt of mono(hydroxybutyl)phthalate [Ca(HBP)2] and polyethylene glycol (PEG200 or PEG400). A series of calcium containing PUEs having different composition were synthesized by taking the mole ratio of Ca(HBP)2:PEG200 or PEG400:diisocyanate (HMDI or TDI) as 3:1:4, 2:2:4 and 1:3:4 to study the effect of calcium content on the properties of the copolymer. The structure of the polymers were confirmed by IR, 1H-NMR, 13C-NMR, and solid state 13C-CP-MAS NMR. The polymers were soluble in dimethyl sulfoxide and dimethyl formamide. The initial decomposition temperature of the polymers decreases with increase in calcium content. The Tg value of PUEs increases with increase in calcium content and decreases with increase in soft segment content and length. A single Tg value is observed for the calcium containing PUEs based on PEG200 shows the presence of homogeneous phase. However, two Tg values for the PUEs based on PEG400 for various composition of Ca(HBP)2, PEG400 and diisocyanate (HMDI or TDI) shows the presence of heterogeneous phase. The viscosity of the calcium containing PUEs increases with increase in the soft segment content as well as its length and decreases with increase in calcium content. X-ray diffraction patterns of the polymers show that the HMDI based polymers are partially crystalline and TDI based polymers are amorphous in nature. The dynamic mechanical analysis of the calcium containing PUEs based on HMDI shows that at any given temperature modulus (g′ and g″) increases with increase in the ionic content in the polymers.