Side-Chain Crystallinity and Thermal Transitions in Thermotropic Liquid-Crystalline Poly(γ-alkyl-α,L-glutamate)s
Side-Chain Crystallinity and Thermal Transitions in Thermotropic Liquid-Crystalline Poly(γ-alkyl-α,L-glutamate)s
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DOI：
10.1021/bk-1992-0493.ch023
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发表时间：
1992-06
期刊：
影响因子：
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通讯作者：
W. Daly;I. Negulescu;P. Russo;D. Poché
中科院分区：
文献类型：
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作者：
W. Daly;I. Negulescu;P. Russo;D. Poché
用差示扫描量热法研究了带有C16(十六烷基)和C18(硬脂基，PSLG)侧链的聚(γ-烷基-α，L-谷氨酸)S的热转变。由相应的NCA合成了PHLG和PSLG(相对分子质量为40K-300K)。通过在适当的温度下对聚合物进行热处理，可以分离石蜡侧链链段的熔融和似乎与液晶的形成密切相关的第二个转变。根据样品的热历史(重复退火和/或淬火)，侧链链段在很大的温度范围内熔化和结晶，这表明形成了不同尺寸的微晶和/或容纳了不同数量的亚甲基单元。热历史也影响到向液晶态的转变；在侧链熔融区域以上的样品观察到最高的液晶态转变温度。
Thermal transitions in poly(γ-alkyl-α,L-glutamate)s with C16 (hexadecyl, PHLG) and C18 (stearyl, PSLG) side-chains were investigated by differential scanning calorimetry. Both PHLG and PSLG (Mw=40K-300K) were synthesized from the corresponding NCA. By annealing the polymers at appropriate temperatures it was possible to separate the melting of paraffinic side chain segments and a second transition that seems to be closely related to the formation of a liquid crystal. Depending on the thermal history of samples (repeated annealings and/or quenchings) the side chain segments melted and crystallized over a large temperature range suggesting the formation of crystallites of different dimensions and/or accommodating a different number of methylenic units. The thermal history also affected the transition to the LC state; the highest LC transition temperatures were observed for samples annealed above the melting domain of side chains.