DSC study of main relaxations in the poly(imide-dimethylsiloxane) block copolymers

Abstract The segmentai dynamics in a series of alternating, phase-separated poly(imidedimethylsiloxane) (PI/PDMS) block copolymers has been studied by differential scanning calorimetry (DSC) over the temperature range of 100–630 K, covering the regions of the glass transition and β-relaxation for soft and rigid blocks. The PI blocks had degrees of polymerization that ranged from 6 to 30, and the PDMS moiety content varied from 10 to 47 mass%. Complex behavior of the low-temperature, PDMS block glass transition characteristics was shown, and the conditions for maintaining the PI domains with high T g, providing thermal stability for these block copolymers, were ascertained. The peculiarities of segmentai dynamics and its heterogeneity observed within the glass transition could be interpreted by using as a basis the concept of the common segmentai nature of the α- and β-transitions in flexible-chain polymers.

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