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Facile Synthesis and Photo-Tunable Behaviors of a Photo-Sensitive Polymer Whose Chromophores Bound with pH-Labile Cycle Acetal Linkages

Author: LiYaoHua
Tutor: CaiYuanLi
School: Xiangtan University
Course: Polymer Chemistry and Physics
Keywords: Light - responsive polymer The cyclic acetal key then Visible light Room temperature RAFT polymerization Photoisomerization Light response behavior
CLC: O631.3
Type: Master's thesis
Year: 2008
Downloads: 77
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Abstract


Light response functional polymers as a new class of intelligent functional materials, showing the incomparable superiority of conventional materials. So far, the light response of functional polymer developed by leaps and bounds Among these light response function of polymer light-induced isomerization-driven light response behavior of functional polymers become today's hot research with its own characteristics. Current information and new energy industry, the rapid development of such emerging optical response function of polymer material put forward higher requirements. How to effectively build a more complex, the optical response of the more advanced features of functional polymers has become the subject of great research value and challenging. In this thesis, from the molecular level Nature as Teacher, imitating animals retinal rhodopsin or halophilic bacteria purple membrane bacteriorhodopsin structural features in the environment-friendly conditions, the use of cinnamic aldehyde, through the the cyclic acetal key then, precisely synthesized light-responsive polymer, and its optical response behavior are analyzed and discussed. This thesis Synthesis of photosensitive cinnamic the cyclic acetal key connected group of photosensitive monomer 5 - ethyl-5-of - methacryloxypropyl methyl -2 - styryl - [1,3] dioxane-cyclohexane ( EMSD), and on the basis of our previous study, select, synthetic dithio ester isobutyronitrile fluoride acid (referred to CPFDB) as chain transfer agent; (2,4,6 - trimethoxy benzoyl group) diphenyl phosphine oxide (TPO), as the light of the polymerization reaction initiator; the the EMSD room temperature RAFT polymerization is completed in the activation of the visible light (lambda gt; 400 nm). The study found that the polymerization reaction with \Resultant homopolymer poly-5 - ethyl-5-of - methacryloxypropyl methyl -2 - styryl - [1,3] dioxane-cyclohexane (referred PEMSD) is a macromolecular chain transfer agent, the use of visible light activation of the RAFT polymerization at room temperature for accurate synthesis of a series of different structures and a narrower molecular weight distribution of the block copolymer was further confirmed by the \The above 1H NMR characterization of the resulting polymer showed that, under polymerization conditions, the cyclic acetal structure intact, photosensitive cinnamyl chromophore in E-configuration. Short-wave ultraviolet light (254-365 nm) according to the cinnamon PEMSD polymer-based Z-isomerization. The results show that light intensity affect the heterogeneous reaction rate, When cinnamic degree of isomerization of the Z-65%, the isomerization reaction to reach equilibrium. PEMSD polymer cinnamic groups the photoisomerization reaction changes in the structure will cause changes on the nature of PEMSD polymer. The study found that the cinnamon PEMSD polymer-based Z-isomerization, the maximum absorption wavelength the PEMSD polymer gradually from 252 nm (containing only E-cinnamic base) blue shift to 244 nm (E-cinnamyl / Z-cinnamyl = 44:56), the molar extinction coefficient values ??decrease from 1.97 × 104 M-1 cm-1 corresponding to 1.41 × 104 M-1 cm-1. We have also found that the, cinnamyl PEMSD Z-isomerization reduces the orderly arrangement of PEMSD polymer chain, to improve the flexibility of the polymer chain, and make the PEMSD polymer has a glass transition temperature from 119 ° C (E contains only - cinnamon yl) reduced to 99 oC (E-cinnamon-cinnamon base, base / Z = 37:63). Note that, in this study, we found, the the cinnamon group the PEMSD polymer Z-isomerization, cinnamyl adjacent to the cyclic acetal, steric hindrance and hydrophobic shielding effect is increased to improve the stability of the cyclic acetal valence bond sex. Its effect is reflected in the hydrolysis of the cyclic acetal, cyclic acetal Z-cinnamyl Nearby significantly less than the degree of hydrolysis degree of hydrolysis of the acetal E-cinnamyl group adjacent to the ring. Such light response Polymer and Its unique light response characteristics of functional materials to provide new ideas for the development of a new generation of light sensors and light control drug release system.

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CLC: > Mathematical sciences and chemical > Chemistry > Polymer chemistry ( polymer ) > Polymer physics and physical chemistry of polymers > The chemical nature of polymers
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