Equilibrium polymerization, polymer glass

Laser Raman spectroscopy has been used as a tool to elucidate the molecular structure of crystals, liquids, and amorphous alloys in the As-S-Se-Te system. Characteristic monomer and polymer structures have been identified, and their relative abundances have been estimated as a function of temperature and atomic composition. These spectroscopic estimates are supported by calculations based on the equilibrium polymerization theories of Tobolsky and Eisenberg (1,2) and of Tobolsky and Owen (3). Correlations between the molecular structure of the amorphous alloys and physicochemical properties such as the electron drift mobility and the glass transition temperature are presented. 

In a recent study (120), measurements were made of the molar cyclization equilibrium constants Kx for cyclics (0(CH2)i00C0(CH2)4C0)x with x = 1—5 in an undiluted equilibrate of poly(decamethylene adipate) (PDA) at 423 K, and for cyclics (0(CH2)30C0(CH2 )2 CO)x with x = 1-7 in an undiluted equilibrate of poly(trimethylene succinate) (PTS) at the same temperature. The polymers were prepared from dimethyl adipate and decamethylene glycol and from dimethyl succinate and 1,3-propane diol using tetraisopropyltitanate and equilibrated at the required temperature in four-necked glass reaction kettles. Cyclics were extracted from the polymeric equilibrates and analysed by g.p.c. by methods described in Ref. (120). Individual cyclics were also prepared from the polyesters by the general pyrolytic method of Carothers and these were used for identification and calibration purposes. 

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