Dependences of Confining Size and Interfacial Curvature on the Glass Transition of Polydimethylsiloxane in Self‐Assembled Block Copolymers

Abstract

Lamellae (LAM), hexagonally packed cylinders (HEX), and double gyroid (GYR) phases of diblock copolymer polydimethylsiloxane‐b‐poly‐2,5‐bis(4‐methoxyphenyl)‐oxycarbonyl styrene (PDMS‐b‐PMPCS) can be obtained by controlling PMPCS length and thermal annealing conditions. This provides a system to study the glass transition of polymers under the well‐defined confining geometries and interfacial physicochemical properties. By taking advantage of ultrafast differential scanning calorimeter, the glass transition temperature (Tg) of PDMS in the confined state is measured without destroying the nanophase structure sustained by the rigid PMPCS domains. Depending on the detailed confining geometry, the Tg and Tg breadth of PDMS show a clear difference by alternating the nanostructure and confining size. When annealing at higher temperatures, the decreases of Tg and Tg breadth with increasing confining size are observed, which are due to the subtle thermal expansion of block copolymer. Besides, the interfacial curvature effect on the Tg of PDMS is emphasized: the confining size dependence on Tg of PDMS block gradually becomes stronger as the interfacial curvature changes from negative (in GYR), to zero (in LAM) and to positive (in HEX). Such results explicitly elaborate the glass transition behavior of PDMS confined in block copolymer with various nanophase structures.

Encounter between Gyroid and Lamellae in Janus Colloidal Particles Self‐Assembled by a Rod–Coil Block Copolymer

“…[ 28–30 ] Therefore, the rod–coil PDMS‐ b ‐PMPCS can self‐assemble into diverse structures through thermal annealing because of the strong phase‐segregation ability, which has advantages in the preparation of complex structures such as double gyroid. [ 31–33 ]…”

“…[28][29][30] Therefore, the rod-coil PDMS-b-PMPCS can self-assemble into diverse structures through thermal annealing because of the strong phasesegregation ability, which has advantages in the preparation of complex structures such as double gyroid. [31][32][33] Chloroform is a good solvent for PDMS and PMPCS, which can be used as the solvent to generate emulsion droplets for D 65 M 25 . When CTAB is used as the single surfactant, the hydrophobic part of CTAB has an affinity for PMPCS while the cation head can stabilize the emulsion droplet in the aqueous solution.…”