Effects of Chain Entanglement on Liquid-Liquid Phase Separation Behavior of LCST-type Polymer Blends： Cloud Point and Decomposition Rate

By preparing homogenous blend samples with different degrees of chain entanglement, we report an anomalous contribution of chain entanglement to phase separation temperature and rate of poly（methyl methacrylate）/poly（styrene-co- maleic anhydride） （PMMA/SMA） blends presenting a typical lower critical...

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Bibliographic Details
Published in:Chinese journal of polymer science 2015-06, Vol.33 (6), p.869-879
Main Authors: Lin, Yu, Shangguan, Yong-gang, Qiu, Bi-wei, Yu, Wen-wen, Chen, Feng, Guo, Zhen-wu, Zheng, Qiang
Format: Article
Language:English
Subjects:
Blends
Chain entanglement
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Condensed Matter Physics
Decomposition
Entanglement
Industrial Chemistry/Chemical Engineering
LCST
Phase separation
Polymer blends
Polymer Sciences
Polymethyl methacrylates
Polystyrene resins
低临界溶液温度
分解率
浊点
相分离行为
聚甲基丙烯酸甲酯
链缠结
高分子共混物
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Summary:By preparing homogenous blend samples with different degrees of chain entanglement, we report an anomalous contribution of chain entanglement to phase separation temperature and rate of poly（methyl methacrylate）/poly（styrene-co- maleic anhydride） （PMMA/SMA） blends presenting a typical lower critical solution temperature （LCST） behavior. The melt- mixed PMMA/SMA blends with a higher chain entanglement density present a lower cloud point （To） and shorter delay time, but lower phase separation rate at the given temperature than solution-cast ones, suggesting that for the polymer blends with different condensed state structure, thermodynamically more facilitation to phase separation （lower Tc） is not necessarily equivalent to faster kinetics （decomposition rate）. The experimental results indicate that the lower Tc of melt-mixed sample is ascribed to smaller concentration fluctuation wavelength （Am） induced by higher entanglement degree, while higher entanglement degree in melt-mixed sample leads to a confined segmental dynamics and consequently a slower kinetics （decomposition rate） dominated by macromolecular diffusion at a comparable quench depth. These results reveal that the chain packing in polymer blends can remarkably influence the liquid-liquid phase separation behavior, which is a significant difference from decomposition of small molecular mixtures.
ISSN:0256-7679
1439-6203
DOI:10.1007/s10118-015-1637-8