Synthesis, physical properties, and crystallization of optically active poly(L‐phenyllactic acid) and poly(L‐phenyllactic acid‐co‐L‐lactic acid)
Synthesis, physical properties, and crystallization of optically active poly(L‐phenyllactic acid) and poly(L‐phenyllactic acid‐co‐L‐lactic acid)
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DOI：
10.1002/app.28986
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发表时间：
2008-12
影响因子：
3
通讯作者：
H. Tsuji;H. Matsuoka;S. Itsuno
中科院分区：
文献类型：
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作者：
H. Tsuji;H. Matsuoka;S. Itsuno
通过L-苯基乳酸和/或L-乳酸在存在下的酸催化直接缩聚反应，成功合成了重均分子量超过6×103 g mol−1的光学活性聚（L-苯基乳酸）（Ph-PLLA）、聚（L-乳酸）（PLLA）和聚（L-苯基乳酸-共-L-乳酸）。 2.5–10 wt% 对甲苯磺酸。通过差示扫描量热法、热重分析和旋光分析研究了它们的物理性质和结晶行为。 Ph-PLLA (−38 deg dm−1 g−1 cm3) 的比旋光度 ([α]) 绝对值远低于 PLLA (−150 deg dm−1 g−1 cm3) 的 [α]，这表明通过引入大的苯基基团降低了螺旋性质。 PLLA 在溶剂蒸发、从室温加热和从熔体冷却的过程中是可结晶的。即使在 4 mol% 的情况下，掺入非常低含量的大苯乳基单元也能抑制加热和冷却过程中 L-乳基单元序列的结晶，尽管在溶剂蒸发过程中，共聚物的 L-苯乳基单元可结晶高达 6 mol%。 Ph-PLLA (200 kJ mol−1) 的热降解活化能 (ΔEtd) 高于 PLLA (158 kJ mol−1)。共聚物的 ΔEtd 随着 L-苯基乳基单元含量的增加而增加。 © 2008 Wiley periodicals, Inc. J Appl Polym Sci，2008
Optically active poly(L-phenyllactic acid) (Ph-PLLA), poly(L-lactic acid) (PLLA), and poly(L-phenyllactic acid-co-L-lactic acid) with weight-average molecular weight exceeding 6 × 103 g mol−1 were successfully synthesized by acid catalyzed direct polycondensation of L-phenyllactic acid and/or L-lactic acid in the presence of 2.5–10 wt % of p-toluenesulfonic acid. Their physical properties and crystallization behavior were investigated by differential scanning calorimetry, thermogravimetry, and polarimetry. The absolute value of specific optical rotation ([α]) for Ph-PLLA (−38 deg dm−1 g−1 cm3) was much lower than that of [α] for PLLA (−150 deg dm−1 g−1 cm3), suggesting that the helical nature was reduced by incorporation of bulky phenyl group. PLLA was crystallizable during solvent evaporation, heating from room temperature, and cooling from the melt. Incorporation of a very low content of bulky phenyllactyl units even at 4 mol % suppressed the crystallization of L-lactyl unit sequences during heating and cooling, though the copolymers were crystallizable for L-phenylactyl units up to 6 mol % during solvent evaporation. The activation energy of thermal degradation (ΔEtd) for Ph-PLLA (200 kJ mol−1) was higher than that for PLLA (158 kJ mol−1). The ΔEtd for the copolymers increased with an increase in L-phenyllactyl unit content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008