Phase Transition Behavior and Nanostructure Orientation of PS-b-P4VP(DBSA) Supramolecular Comb-coil Block Copolymer

林怡君(Lin, Yi Chun)

指導教授 ： 陳信龍

國立清華大學/工學院/化學工程學系/碩士(2011年)

https://doi.org/10.6843/NTHU.2011.00210

摘要

We undertook an investigation on the hierarchical self-assembly behavior of the comb-coil block copolymer formed by complexation between a lamellae-forming PS-b-P4VP and an amphiphilic surfactant, DBSA. An aim of of our study was to ascertain the effect of the grafting density (x) of DBSA to a 4VP and the relative orientation of nanostructures on the copolymer domain structure. Large-amplitude oscillating shear (LAOS) was performed under fine shearing condition to produce large-scale alignment of the microdomains. We employed small-angle X-ray scattering (SAXS) and transmission election microscopy (TEM) to observe the morphologies of those samples. With increasing binding fraction, the system exhibits a series of structure transition associated with PS microdomain from lamellae to hexagonally-packed cylinder to coexistence of tetragonal- and hexagonally-packed cylinder ,and eventually to hexagonally-packed cylinder again. Particularly interesting scenario is the hierarchy containing tetragonally-packed cylinder at intermediate to higher binding fraction. The tetragonal symmetry may be a metastable phase due to its slightly efficient packing. In addition, the orientation of small-scale lamellae organized by the comb block with respect to the larger-scale PS microdomain is identified. The parallel arrangement of the small-scale lamellae to the PS domain interface is observed at lower binding fraction and the perpendicular orientation sets in at higher binding fraction. The observed structural transition is explained based on the interplay between the driving force of attaining the spontaneous curvature governed by the interface energy and conformational relaxation of PS block for the two blocks and the driving force of mesophase formation of the comb block. The parallel organization is induced by the driving forces originated from interfacial energy of diblock copolymers as well as the conformational entropy of PS blocks. While, the perpendicular orientation is the favorable structure once the interlamellar interaction governs the lamellar organization.

關鍵字

X光小角度散射 ； 梳狀高分子

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