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首页> 外文学位 >Asymmetric polymeric membranes: On their formation by thermally induced phase separation and the development of photoresponsive composite membranes.
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Asymmetric polymeric membranes: On their formation by thermally induced phase separation and the development of photoresponsive composite membranes.

机译：不对称聚合物膜：通过热诱导相分离形成，并形成光响应性复合膜。

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摘要

Concerning the formation and properties of asymmetric polymeric membranes, this thesis research can be classified into two major categories. In the first part, membranes were developed by thermally induced phase separation (TIPS) techniques and characterized by both scanning electron microscopy (SEM) and mercury intrusion analysis. The effects of the phase separation mechanism, solvent properties, and coarsening on the formation of microporous polymethylmethacrylate (PMMA) membranes were investigated. Experimental observations indicated that during the very early stage of phase separation by spinodal decomposition, a lacy, interconnected membrane structure with good material strength results. In contrast, a fragile membrane structure composed of strings of small beads is a consequence of the early stages of phase separation by nucleation and growth. This study illustrates that a detailed phase diagram is the key to a true understanding of the formation of microcellular structure. For the first time in a membrane formation study, detailed cloud point and spinodal curves were obtained by both optical density and differential scanning calorimetry (DSC) techniques. For membranes prepared by quickly quenching viscous polymer solutions into the demixing region, the membrane morphology observed by SEM can be interpreted consistently in accordance with the location of the metastable and unstable regions as determined by DSC. In designing a well-defined structure with good material strength, this study illustrates not only the importance of the phase diagram but also the significance of choosing a system viscous enough to inhibit phase separation from nucleation and growth during quenching to the unstable region.; In the second part, PMMA was modified by covalently incorporating a photoresponsive unit (trans-4-stilbene methylacrylate or TSMA) into the PMMA backbone as a side group. A novel photoresponsive copolymer (poly(MMA-co-TSMA)) with various ratios of comonomer compositions was developed by free radical copolymerization and characterized by NMR spectroscopy. Its photoresponsive behavior in both solution and solid state was then investigated by various techniques. Significant changes upon irradiation in viscosity, solubility, the glass transition temperature (Tg) and gas permeability were observed. In terms of permeability, this study suggests an excellent potential for developing photoregulatable thin-film composite membrane.
机译：关于不对称聚合物膜的形成和性质，本论文的研究可分为两大类。在第一部分中，通过热诱导相分离（TIPS）技术开发了膜，并通过扫描电子显微镜（SEM）和压汞分析对其进行了表征。研究了相分离机理，溶剂性质和粗化对微孔聚甲基丙烯酸甲酯（PMMA）膜形成的影响。实验观察表明，在通过旋节线分解进行相分离的非常早期阶段，就形成了具有良好材料强度的花边状，相互连接的膜结构。相反，由小珠串组成的易碎的膜结构是由于成核和生长而进行相分​​离的早期阶段的结果。这项研究表明，详细的相图是真正了解微孔结构形成的关键。在膜形成研究中，这是第一次通过光密度和差示扫描量热法（DSC）技术获得详细的浊点和旋节线曲线。对于通过将粘性聚合物溶液快速淬灭到混合区域中而制得的膜，可以通过DSC确定的亚稳和不稳定区域的位置一致地解释通过SEM观察到的膜形态。在设计一个具有良好材料强度的轮廓分明的结构时，这项研究不仅说明了相图的重要性，而且说明了选择足够粘稠的体系以抑制淬火至不稳定区域时从成核和生长中分离相的重要性。在第二部分中，通过将光响应单元（反式-4-苯乙烯甲基丙烯酸酯或TSMA）共价结合到PMMA主链中作为侧基，对PMMA进行了改性。通过自由基共聚反应开发了一种具有不同比例共聚单体组成的新型光响应共聚物（聚（MMA-co-TSMA）），并通过NMR进行了表征。然后通过各种技术研究其在溶液和固态下的光响应行为。观察到辐照后粘度，溶解度，玻璃化转变温度（Tg）和气体渗透率发生了显着变化。在渗透性方面，这项研究表明开发光调节性薄膜复合膜具有极好的潜力。

著录项

  • 作者

    Tsai, Fu-Jya.;

  • 作者单位

    Northwestern University.;

  • 授予单位 Northwestern University.;
  • 学科 Engineering Civil.; Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1990
  • 页码 181 p.
  • 总页数 181
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 建筑科学;工程材料学;
  • 关键词

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