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Synthesis and Properties of Polymers with Multiple Topologies

Author: ZhouYueMing
Tutor: LiuShiYong
School: University of Science and Technology of China
Course: Polymer Chemistry and Physics
Keywords: Block copolymer Topology Supramolecular self-assembly Controlled radical polymerization Click Chemistry
CLC: O631.3
Type: PhD thesis
Year: 2008
Downloads: 588
Quote: 2
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Abstract


The important aspect of the topological structure of the molecular chain of the polymer properties such as the polymer structure characterized in assembling properties, thermal properties, mechanical properties, etc. have an important impact. However, due to some special topological structure of the polymer, such as a ring polymer, multi-block polymers, there is a big difficulty in the preparation of the current research in this area is still more space. Yl so, this thesis combines much attention in recent years, the controlled radical polymerization, Click Chemistry (Click Chemistry), supramolecular self-assembly of the polymer prepared by a variety of topologies, the molecular chain structure include diblock linear and ring-type polymer, multi-block polymers, as well as special star polymer, etc., and to study its supramolecular self-assembly and the thermal performance of the unique nature. Specifically, the work of this paper include the following aspects: (1) Synthesis and Properties of the diblock polymer, let xanthate exchange macromolecular design (macromolecular design via the interchange of xanthates, MADIX ) Preparation of a temperature-sensitive hydrophilic polymer poly (N, N-bis methyl acrylamide)-b-poly (N-vinyl caprolactam) (PDMA-b-PVCL), the temperature of such polymers is sensitive and common-containing poly (N-isopropyl acrylamide) (PNIPAM) chain hydrophilic polymer similar, but due to the good the biocompatibility of PVCL than PNIPAM, so it has a broad application prospects. Further, we use the ATRP preparation of an aqueous solution having multiple temperature-responsive poly (4 - vinylpyridine) -6 - Poly (N-isopropylacrylamide) (P4VP-b-PNIPAM), by adding an acidic aqueous solution 8 - aminonaphthalene-1 ,3,6 - Three-sulfonic acid disodium salt (ANTS), found that the system at low temperatures due to the the protonated P4VP block sulfonate complexing assembled into vesicles under high temperature and then assembled into PNIPAM nuclear micelles, while in the intermediate temperature polymer in molecular dissolved state, that would enable the system by simply warming occurs transition from vesicles to micelles. Finally, we combined ATRP supramolecular self-assembly and Click reaction, the success achieved linear precursor polymer at higher concentrations intramolecular ring closure reaction, while inhibiting the coupling reaction between the precursor molecules, so as to achieve efficient The purpose of ring-type block polymer prepared in the high yield, the resulting pH-sensitive ring-type block polymer of poly (methyl acrylate, 2 - dimethylamino-ethyl) -6 - (methyl acrylate, 2 - diethylamine yl ester) (the Cyclic-PDMAEMA-b-PDEAEMA) and its linear precursor compared to exhibit not the same as the self-assembling properties. Preparation and Properties of the multi-block polymers, we synthesized a new linear poly thioester, with its chain transfer agent prepared by RAFT polymerization of a series of different degree of polymerization temperature-sensitive global The hydrophilic multi-block polymer m-PDMA-PNIPAM, were studied their gelation behavior in the the micellization behavior under low concentration and higher concentrations. Found that this particular structure of the polymer phase transition behavior of the two concentrations within its PDMA and PNIPAM block length are closely related. At low concentrations, the PNIPAM chain longer PDMA chain shorter, the aqueous solution warming generate multiple molecular micellar aggregates; PDMA block longer PNIPAM block shorter, heating system generated unique single-molecule micelles. Accordingly, the former at a high concentration C phase separation occurs can not form a physical gel, and the latter to form a stable physical gel. PNIPAM-b-PDMA-PNIPAM triblock polymer gel obtained as compared to the gel strength obtained by the multi-block better, the lower the critical gelling concentration (COC), while adding a small molecule, an inorganic salt, can effectively enhance the strength of the gel while the ABA type polymers can greatly reduce the salt CGC but little influence on the multi-inlay degrees polymer. In the basis of this work, we have prepared a multi-block polymers MP (NIPAM-co-DMA)-b-P4VP, the acidic aqueous solution in small molecules salt 2,6 - naphthalene dicarboxylic-sulfonate (NDSNa) exhibit multiple temperature response phase-transition behavior: the system under low and high temperature gel state, while in the intermediate temperature (within the range of human body temperature) system is a free flowing polymer solution state, i.e. heating system can occur Gel -Sol-Gel special phase transition, which has not been reported in the previous literature. The basis of the first two parts work, we have further committed to the polymer nano self-assembly structure fixed. In the first part of the work, the reaction was prepared by the Click of a new kind of amino group-containing monomer acrylamide-1-3'-amino-propyl-4 ,2,3 - triazole ring (APAT), the use of The RAFT polymerization NIPAM block polymer PNIPAM-b-PAPAT. LCST effect by means of the on PAPAT block containing the amino group and PNIPAM block, at 20 ° C and 50 ° C of an aqueous solution separately prepared CCL micelles and SCL micelles, further, we use a Click reaction , 2,3 - triazole ring strong complexation of metal and stabilizing effect on the CCL micelles kernel SCL micelles shell with gold nanoparticles selective modification. In the second part of the work, we use the RAFT polymerization of a different block than the poly (trimethoxysilylpropyl methacrylate)-b-poly-ethylene oxide-b-poly (trimethoxysilylpropyl methacrylate) (PMPS-b-PEO 104 -b-PMPS), the morphology of the self-assembly of the ABA type of amphiphilic polymer in an aqueous solution can be fitted by adjusting the PMPS segment length and the initial polarity of the organic polymer to be changed. More importantly, due to the PMPS block containing the the easily hydrolyzed crosslinked-Si-(OCH 3 ) 3 function group, the morphology of the assembly can be in the assembly at the same time get a fixed structure, convenient shortcut preparation for structural stability of nano-assembly provides a useful reference for us. 4 In the last chapter, we are committed Synthesis and thermal properties of new star polymers. The work of the first topic, we first prepared through the first arm of the law containing polystyrene (PS) star polymer chain precursor, its unique in that, in this star polymers on the surface of each arm with two alkynyl functional groups. Next, we synthesized a regular structure containing eight azide functional group inorganic molecules - the multi-faceted Oligomeric Silsesquioxane (POSS), its cross-linking agent, we soon dilute concentrations to achieve the Click reaction surface crosslinking precursor star polymer molecules to give the outer surface of the inorganic molecular crosslinking, the inner layer is an organic polymer, a star polymer, this new type of star polymers exhibit excellent thermal stability performance. In the second subject of the work, we have adopted the first nuclear \like polymer arm intramolecular coupling or two POSS-core, non-linear annular PS arm star-shaped polymer, DSC tests show that this star polymers showed slightly than the precursor stellate polymer high glass transition temperature.

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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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