Influence of Chemical Structures on Isodimorphic Behavior of Three Different Copolycarbonate Random Copolymer Series,Macromolecules

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Influence of Chemical Structures on Isodimorphic Behavior of Three Different Copolycarbonate Random Copolymer Series
Macromolecules ( IF 5.1 ) Pub Date : 2020-01-10 , DOI: 10.1021/acs.macromol.9b02078
Idoia Arandia ₁ , Leire Meabe ₁ , Nora Aranburu ₁ , Haritz Sardon ₁ , David Mecerreyes _{2,

3} , Alejandro J. Müller _{1,

2}

Affiliation

Three series of aliphatic random copolycarbonates, poly(heptane-co-dodecane carbonate) P7C–P12C, poly(butane-co-dodecane carbonate) P4C–P12C, and poly(butane-co-heptane carbonate) P4C–P7C, were synthesized by a two-step polycondensation process. The organocatalyst 4-(dimethylamino)pyridine was used for the first time to prepare copolycarbonates, as an alternative to metal catalysts, to avoid the toxicity of the remaining catalyst impurities that are difficult to remove after synthesis. Differential scanning calorimetry (DSC) studies demonstrated the isodimorphic character of the copolycarbonates showing pseudoeutectic points and crystallization in a wide composition range. Wide-angle X-ray scattering (WAXS) results displayed changes in crystallographic plane spacings possibly because of the isodimorphic behavior of the systems. Two double crystalline copolymers were obtained, that is, 85/15 P4C–P12C and 80/20 P7C–P12C, as they correspond to pseudo-eutectic compositions. Remarkably, for the 80/20 P7C–P12C copolycarbonate, we found a novel behavior. This copolymer exhibits both coincident crystallization and coincident melting during nonisothermal DSC runs. However, WAXS revealed that the material is double crystalline as it contains crystals from P7C-rich and P12C-rich phases. This is the first example of a double crystalline polymeric material that exhibits a single crystallization and a single melting peak in spite of being double crystalline. Comparing the results obtained for the three series of copolycarbonates, we conclude that it is easier to incorporate a shorter repeating unit chain segment in a crystal formed by a larger repeating unit chain segment.

中文翻译：

化学结构对三种不同共聚碳酸酯无规共聚物系列同构行为的影响

三个系列的脂肪族共聚碳酸酯无规，聚（庚烷的共-dodecane碳酸酯）P7C-P12C，聚（丁烷共-dodecane碳酸酯）P4C-P12C，和聚（丁烷共碳酸庚烷）P4C-P7C，是通过两步缩聚法合成的。首次使用有机催化剂4-（二甲基氨基）吡啶来制备共聚碳酸酯，以替代金属催化剂，以避免合成后难以除去的剩余催化剂杂质的毒性。差示扫描量热法（DSC）研究表明，共聚碳酸酯的同构特征表明其伪共晶点和结晶范围很广。广角X射线散射（WAXS）结果显示了晶面间距的变化，这可能是由于系统的同构行为引起的。获得了两种双晶共聚物，即85/15 P4C-P12C和80/20 P7C-P12C，因为它们对应于假共晶成分。值得注意的是对于80/20 P7C–P12C共聚碳酸酯，我们发现了一种新颖的行为。在非等温DSC运行期间，该共聚物既显示结晶，又显示熔融。但是，WAXS显示该材料是双晶的，因为它包含富P7C和富P12C相的晶体。这是双晶聚合物材料的第一个例子，尽管它是双晶的，但仍显示出单晶和单熔化峰。比较三组共聚碳酸酯获得的结果，我们得出结论，将较短的重复单元链段掺入由较大的重复单元链段形成的晶体中比较容易。WAXS显示该材料为双晶，因为它包含来自富P7C和富P12C相的晶体。这是双晶聚合物材料的第一个例子，尽管它是双晶的，但仍显示出单晶和单熔峰。比较三组共聚碳酸酯获得的结果，我们得出结论，将较短的重复单元链段掺入由较大的重复单元链段形成的晶体中比较容易。WAXS显示该材料为双晶，因为它包含来自富P7C和富P12C相的晶体。这是双晶聚合物材料的第一个例子，尽管它是双晶的，但仍显示出单晶和单熔化峰。比较三组共聚碳酸酯获得的结果，我们得出结论，将较短的重复单元链段掺入由较大的重复单元链段形成的晶体中比较容易。

更新日期：2020-01-13

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