Quantitative description of aggregation and dissociation of poly (vinyl methyl ether)/poly (2-ethyl-2-oxazoline) chains in water by novel elastic light scattering spectroscopy

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• 作者：Wenzhi Zhang (1) (2)
  Xudong Chen (1)
  Mingqiu Zhang (1)
  
• 关键词：Elastic light scattering spectroscopy ; Phase transition ; Aggregation ; Poly (vinyl methyl ether) ; Poly (2 ; ethyl ; 2 ; oxazoline)
• 刊名：Polymer Bulletin
• 出版年：2014
• 出版时间：January 2014
• 年：2014
• 卷：71
• 期：1
• 页码：243-260
• 全文大小：716 KB
• 作者单位：Wenzhi Zhang (1) (2)
  Xudong Chen (1)
  Mingqiu Zhang (1)
  
  1. Key Laboratory for Polymer Composite and Functional Materials of the Ministry of Education, DSAPM Lab, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, 510275, People鈥檚 Republic of China
  2. School of Materials and Chemical Engineering, Xi鈥檃n Technological University, Xi鈥檃n, 710021, People鈥檚 Republic of China
  
• ISSN：1436-2449

文摘

Phase transition process in aqueous solutions of poly (vinyl methyl ether) (PVME)/poly (2-ethyl-2-oxazoline) (PEtOx) mixtures was investigated by elastic light scattering (ELS) spectroscopy. The two temperatures of phase transition in solutions during heating were identified, corresponding to different lower critical solution temperatures of PVME and PEtOx. The ELS spectra revealed the aggregation of molecular chains in the course of phase transition. It was found that PVME chains collapsed and aggregated during heating. Afterward, the PEtOx chains began to aggregate. In contrast, during cooling, the PEtOx aggregates were initially swelled and followed by partial dissociation. This was probably because that the PVME aggregates formed in solution might sterically hinder the further swelling and dissociation of the PEtOx aggregates. Subsequently, the aggregates of PVME chains and the independent PEtOx aggregates swelled and dissociated, while the conformation of molecular chains finally returned to its original state. In view of the phase transition behavior of PVME/PEtOx solutions, the mixtures of two thermosensitive polymers might be used to develop new polymeric materials possibly applied in fields such as drug delivery, biosensor, and bioseparation. Moreover, a model was proposed to describe the phase transition process.