Miscible Blends of Stereoregular Poly(methyl methacrylate) and Poly(hydroxy ether of Bisphenol A)

Isotactic, atactic, and syndiotactic poly(methyl methacrylates) (PMMAs) (designated as iPMMA, aPMMA, and sPMMA) were mixed with poly(hydroxy ether of Bisphenol A) (phenoxy) separately in 2-butanone to make three polymer blend systems. Differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy were used to study the miscibility of these blends. The three polymer blends were found to be miscible because all the prepared films were transparent and there was a single glass transition temperature (Tg) for each composition of the blends. Tg values of the sPMMA/phenoxy blends correspond well to weight average predictions. Since Tg values of aPMMA and phenoxy are close, naturally their blends’ Tgs are not different from weight average. However, Tg values of the iPMMA/phenoxy blends are below weight average and can be fitted well by the Gordon—Taylor equation with a k value of 0.38. The IR spectra of carbonyl absorption showed little hydrogen bonding since virtually no shift was observed. However, the spectra in the region of hydroxyl absorption indicated a certain degree of hydrogen bonding between PMMA and phenoxy. Upon mixing with PMMA, the broad hydrogen bonded hydroxyl band of the phenoxy was observed to shift to higher frequencies as a function of increasing PMMA concentration. Using the magnitude of the peak shift of the hydrogen bonded hydroxyl band as an indicator of interaction between PMMA and phenoxy, sPMMA was determined to have the highest degree of hydrogen bonding with phenoxy among the three tactic PMMAs. Based on the results of IR spectra, the intra-hydrogen bonding (OH-OH) interaction of phenoxy was found to be stronger than the interhydrogen bonding (OH-O=C) interaction between PMMA and phenoxy.