Crystalline structure and morphology of microphases in compatible mixtures of poly(tetrahydrofuran-methyl methacrylate) diblock copolymer and polytetrahydrofuran
✍ Scribed by Li-Zhi Liu; Benjamin Chu
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 277 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0887-6266
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✦ Synopsis
The crystalline structure and morphology of compatible mixtures of poly-(tetrahydrofuran-methyl methacrylate) diblock copolymers (PTHF-b-PMMA) with a polytetrahydrofuran homopolymer (PTHF) were studied with synchrotron X-rays. Wide-angle diffraction was used to study the crystalline structures in a confined lamellar region with a PTHF thickness ranging from 12.2 to 19.5 nm, and in a PTHF matrix with an interface distance between the PMMA cylinders ranging from 17 to 22 nm. As the above thickness values are around the long period (ca. 17 nm) of PTHF homopolymer under the crystallization condition used, the crystalline structure has been found to be very sensitive to the average thickness of the PTHF phase. The changes in the diffraction patterns with changing PTHF homopolymer content suggested a chain folding model in confined PTHF lamellae with the PTHF fiber axes being perpendicular to the thick PTHF lamella. In the case of hexagonally packed cylindrical PMMA microdomains with an interface distance ranging from 12 to 16 nm, the effects of PMMA cylinders on the crystallization morphology of PTHF in the PTHF matrix, and the effects of the PTHF crystallization on the hexagonally packed structure of PMMA cylinders were also studied. It is shown that only when the interdistance of two neighboring PMMA cylinders is comparable with the long period of the pure PTHF homopolymer, ordered PTHF stacks can be formed in the PTHF matrix.