Synthesis, stereocomplex crystallization and homo-crystallization of enantiomeric poly(lactic acid-co-alanine)s with ester and amide linkages
Synthesis, stereocomplex crystallization and homo-crystallization of enantiomeric poly(lactic acid-co-alanine)s with ester and amide linkages
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DOI：
10.1039/c7py02024d
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发表时间：
2018-01
影响因子：
4.6
通讯作者：
H. Tsuji;Shotaro Sato;Noriaki Masaki;Yukiharu Arakawa;A. Kuzuya;Y. Ohya
中科院分区：
文献类型：
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作者：
H. Tsuji;Shotaro Sato;Noriaki Masaki;Yukiharu Arakawa;A. Kuzuya;Y. Ohya
以L-丙交酯和（3S，6S）-3，6-二甲基吗啉-2，5-二酮为单体，分别与D-丙交酯和（3R，6 R）-3，6-二甲基吗啉-2，5-二酮共聚，合成了α-羟基和α-氨基酸衍生的聚（L-乳酸-L-丙氨酸）共聚物和聚（D-乳酸-D-丙氨酸）共聚物。研究了乳酸单元中的丙氨酸单元或酯键中的酰胺键对溶液和熔融结晶50/50共混样品以及溶液和熔融结晶非共混样品的结晶行为的影响。本文首次报道了具有酯键和酰胺键的对映体无规共聚酯酰胺聚（乳酸-co-丙氨酸）之间的立体复合物（SC）的形成。溶液结晶的非共混样品在L-丙氨酸单元含量高达6摩尔%或D-丙氨酸单元含量高达3摩尔%的情况下以α-或δ-形式均质微晶结晶，而所有熔融结晶的样品在L-或D-丙氨酸单元含量至少高达12和13摩尔%的情况下以α-或δ-形式均质微晶结晶。相比之下，丙氨酸单元含量为0-13摩尔%的溶液结晶共混样品和丙氨酸单元含量为4-13摩尔%的熔融结晶共混样品仅在SC微晶中结晶，而丙氨酸单元含量为0摩尔%的熔融结晶共混样品[即，聚（L-乳酸）/聚（D-乳酸）共混物]以SC微晶和均微晶结晶。熔融结晶的非共混样品的丙氨酸单位被纳入同质结晶区域，而那些溶液结晶的非共混样品被排除在同质结晶区域。与此相反，溶液结晶的共混样品的丙氨酸单元被纳入SC结晶区，而那些熔融结晶的共混样品被排除在SC结晶区。
α-Hydroxy acid and α-amino acid-derived poly(L-lactic acid-co-L-alanine)s and poly(D-lactic acid-co-D-alanine)s with different alanine unit contents were synthesized by copolymerization of L-lactide and (3S,6S)-3,6-dimethyl-morpholine-2,5-dione and of D-lactide and (3R,6R)-3,6-dimethyl-morpholine-2,5-dione, respectively. The effects of the incorporated alanine units in lactic acid units or amide linkages in ester linkages on the crystallization behavior of solution- and melt-crystallized 50/50 blended samples as well as that of solution- and melt-crystallized nonblended samples were investigated. This article reports for the first time a stereocomplex (SC) formation between enantiomeric random copolyesteramides poly(lactic acid-co-alanine)s with ester and amide linkages. The solution-crystallized nonblended samples crystallized in α- or δ-form homo-crystallites for an L-alanine unit content up to 6 mol% or a D-alanine unit content up to 3 mol%, whereas all the melt-crystallized samples crystallized in α- or δ-form homo-crystallites for the L- or D-alanine unit content at least up to 12 and 13 mol%. In contrast, the solution-crystallized blended samples with the alanine unit contents of 0–13 mol% and the melt-crystallized blended samples with the alanine unit contents of 4–13 mol% crystallized only in SC crystallites, whereas the melt-crystallized blended samples with an alanine unit content of 0 mol% [i.e., poly(L-lactic acid)/poly(D-lactic acid) blends] crystallized in both SC crystallites and homo-crystallites. The alanine units of melt-crystallized nonblended samples were incorporated into homo-crystalline regions, whereas those of solution-crystallized nonblended samples were excluded from homo-crystalline regions. In contrast, the alanine units of solution-crystallized blended samples were incorporated into SC crystalline regions, whereas those of melt-crystallized blended samples were excluded from SC crystalline regions.