Triblock copolymers differential scanning

The PMMA-fc-PMPS-fe-PMMA triblock copolymers prepared by the macroinitiator approach using ATRP [60] were only characterized using differential scanning calorimetry. The glass transition temperature (T of PMPS is usually difficult to observe but within the copolymers it was clearly evident at 125-130°C. The T s of the PMMA blocks increased with block length in a manner consistent with the variation with chain length for homopolymers of PMMA and were also clearly visible by DSC. The presence of two T s provides strong evidence for microphase separation of the blocks. 

Krause, S., Lu, Z.-H., and Iskander, M., Rroperties of low molecular weight block copolymers 4. Differential scanning calorimetry and refractive index-temperature measurements on styrene-butadiene diblock copolymers and styrene-butadiene-styrene triblock copolymers. Macromolecules, 15,1076-1082 (1982b). 

A quantitative thermal method, based on the differential of heat capacity signal from modulated temperature differential scanning calorimetry, was described for determining the weight fraction of interface and the extent of phase separation in polymer materials. The interface was modelled as discrete fractions, each with its own characteristic increment of heat capacity. The materials used to demonstrate the range of the method were PS blended with poly(phenylene oxide) (PPO), pure PS, pure PPO, a styrene-isoprene-styrene triblock copolymer (SIS), SIS blended with PPO, PMMA/poly(vinyl acetate) blends and PVC sandwiched with poly(n-butyl acrylate). Two-phase and four-phase systems were used. The calculated results agreed well with experimental results for two- and four-phase systems. 20 refs. 

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