摘要
以含聚异丙二醇(PPG)链段的聚醚胺和己二酸为原料,合成了温度响应性聚酰胺APA;FT-IR和GPC的结果表明合成产物具有酰胺结构的聚合物;Micro-DSC和变温紫外测试的结果表明,合成的APA具有33℃的最低临界互溶温度;TEM和AFM的结果表明当组装体溶液浓度为1 mg/m L时,APA在常温下可以组装成长纤维,其形成经历了"胶束-胶束多聚体-胶束融合-长纤维"等多级自组装过程.而当温度升为60℃,这些长纤维会转变为平均螺距为35 nm的螺旋纤维.螺旋纤维的形成本质上是当温度高于LCST时,APA纤维中的PPG链段坍塌,从而诱导纤维发生扭转,最终导致螺旋结构的出现.
Herein, we reported the synthesis and self-assembly of a novel temperature-responsive polyamide. The temperature-responsive polyamides（APA） was synthesized by forming-salts and solution-melt polycondensation based on the hexanedioic acid and temperature-responsive poly（propylene glycol） bis（2-aminopropyl ether）. The polyamide structures of as-prepared polyamides were ascertained by Fourier transform infrared spectroscopy（FT-IR） measurement. And the gel permeation chromatography（GPC） curve showed that the as-prepared temperature-responsive polyamide possessed a distribution with a number-average molecular weight of 17800 Da and a polydispersity of 2.91. The micro differential scanning calorimetry（Micro-DSC） and UV results showed that the APA possessed a LCST of 33 ℃. Then a direct hydration method was used to induce the self-assembly of APA by putting polymers into deionized water with a concentration of 1.0 mg/m L at room temperature. On the other hand, we also prepared the other self-assemblies through the same direct hydration method while the temperature is at 60 ℃, which is beyond the LCST of as-prepared APA. The transmission electron microscope（TEM） images ascertained that the as-prepared APA should self-assemble into normal fibers at room temperature（c=1.0 mg/m L）. And the formation of these long fibers are attributed to the aggregation and fusion of the primary polyamide micelles. However, very interesting, when the temperature was increased to 60 ℃, the atomic force microscope（AFM） and TEM results showed that the original fibers have transformed into helical fibers with more than 5 μm length. And the average helix pitch was about 35 nm. This fascinating morphology transformation should be attributed to the solubility change of PPG segments in APA fibers. When the temperature was increased to 60 ℃ beyond the LCST of APA, the solubility of PPG segments would decrease, and the PPG segments would also collapse. And what＇s more, due to an alternating hydrophilic/hydrophobic structure of APA, and the PPG segments on the surface of the APA fibers should twist. Finally, the helical APA fibers have been obtained. The present work represents a new progress for macromolecular self-assembly.
作者
黄磊
黄通
白永平
周永丰
Huang Lei Huang Tong Bai Yongping Zhou Yongfeng(School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001 School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240)
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2016年第12期990-994,共5页
Acta Chimica Sinica
基金
国家重点基础研究发展计划(973计划
No.2013CB834506)
国家杰出青年基金(No.21225420)
国家自然科学基金(Nos.21474062
91527304)资助~~
关键词
温度响应性
聚酰胺
多级自组装
螺旋
纤维
temperature-responsive
polyamides
-hierarchical self-assembly
helical
fibers
作者简介
E-mail： baifengbai@hit.edu.cnE-mail： yfzhou@sjtu.edu.cn
