利用“RAFT”聚合和“Click”反应合成“8”形聚合物
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摘要
聚合物的性能与其结构密切相关。近年来,各种非线性结构聚合物,如星形、环形、树枝状聚合物等的合成受到广泛关注。其中,环形聚合物由于没有端基,其分子链上的单元具有等效性;和其它拓扑结构的聚合物相比,在某些方面具有特殊的性质,包括玻璃化转变温度、自组装行为和表面性质等,因此一直受到高分子领域研究人员的关注。本论文对“8”形聚合物的合成进行了研究,先通过可逆加成-断裂链转移自由基(RAFT)聚合反应合成了一系列含氮叠端基的四臂星形聚合物,再利用N,N-二(2-炔丙氧羰基乙基)-2-羟乙胺(BPHA)作为偶联剂经“Click”反应用合成了一系列“8”形聚合物。本论文的主要研究工作有以下几个方面:
(1)采用两步反应合成一种新型含叠氮端基的四官能度三硫代酯类链转移剂3-(S-(2-乙酸2-叠氮乙酯基)三硫代碳酸酯)丙酸季戊四醇四酯(PeAATP),并用RAFT聚合反应合成四臂星形聚合物(S-[DMA]_4、S-[NIPAM]_4及S-[PDMA-b- PNIPAM]_4)。用凝胶色谱(GPC)测定了所得聚合物的数均分子量(Mn)以及分子量分布(PDI)。结果表明,链转移剂PeAATP对聚合反应有较好的调控性,所得到的四臂星形聚合物分子量可控、分子量分布较窄,为“活性”聚合反应。
(2)在CuBr/PMDETA催化剂存在条件下,通过N,N-二(2-炔丙氧羰基乙基)-2-羟乙胺(BPHA)与超稀浓度的四臂星形聚合物溶液的“Click”反应,合成“8”形聚合物。用FT-IR、1H NMR、GPC和MALDI-TOF MS对所合成的聚合物进行了表征。FT-IR谱图中2100 cm~(-1)处叠氮基吸收峰消失证明聚合物中叠氮基已经全部反应;1H NMR谱图上在δ= 8.42 ppm处出现新吸收峰表明三咪唑环生成;GPC测试表明成环后聚合物分子量降低,MALDI-TOF MS结果表明反应前后聚合物分子量几乎不变,证明“Click”反应是分子内成环而非分子间缩合。DLS结果表明,“8”形PDMA-b-PNIPAM的临界胶束温度(CMT)比其四臂前驱体低,而形成胶束后胶束的流体力学直径(Dh)也比其四臂前驱体的小。
Cyclic topological polymers including single and multiple cyclic polymers have attracted a growing interest for the past decades as a result of their unique properties comparing with their branched and linear counterparts. Double cyclic polymers, including 8-shaped, theta-shaped and manacle-shaped polymers are an important class of cyclic topological polymers. Among there three double cyclic polymer topologies, the 8-shaped polymer has been investigated the most. But most of the synthetic strategies reported are based on anionic, cationic, or ring-expansion polymerization. The monomers used are limited and rigorous experiment conditions are needed. In this thesis, a series of well defined 8-shaped polymers, including poly(N,N-dimethyl- acrylamide) (PDMA), poly(N-isopropylacrylamide) (PNIPAM) and poly(N,N-di- methylacrylamide)-b-poly(N-isopropylacrylamide) (PDMA-b-PNIPAM) with controll molecular weight and narrow polydispersity were synthesized by the combination of RAFT polymerization and“Click”chemistry.
Firstly, four-arm star polymers with azido groups were prepared by RAFT polymerization using pentaerythritoltetrakis(3-(S-(2-azidoethylacetate)trithiocarbonyl) propanoate) (PeAATP) as the chain transfer agent. It can be concluded from the GPC results that the polymerization is preceded with good control. Then the intramolecular Click ring closure of the four-arm star polymers was conducted under highly dilute conditions, using N,N-bis(2-propargyloxycarbonyl ethyl)-2-hydroxylethyl amine (BPHA) as linker and CuBr/PMDETA as the catalyst, respectively, affording well-defined 8-shaped polymers. FTIR, 1H NMR, GPC, and MS analysis confirmed the complete consumption of azido group in four-arm star polymers and that the coupling reaction proceeded via the intramolecular manner. The self-assembly behavior of 8-shaped PDMA-b-PNIPAM was investigated by DLS. Comparing with their four-arm star precursor, the 8-shaped polymers possesse lower CMT and smaller hydrodynamic diameter (Dh). The difference in self-assembly behaviors between 8-shaped and four-arm star PDMA-b-PNIPAM should be due to the absence of chain ends and stringent restrictions on backbone conformation in the former.
(1)采用两步反应合成一种新型含叠氮端基的四官能度三硫代酯类链转移剂3-(S-(2-乙酸2-叠氮乙酯基)三硫代碳酸酯)丙酸季戊四醇四酯(PeAATP),并用RAFT聚合反应合成四臂星形聚合物(S-[DMA]_4、S-[NIPAM]_4及S-[PDMA-b- PNIPAM]_4)。用凝胶色谱(GPC)测定了所得聚合物的数均分子量(Mn)以及分子量分布(PDI)。结果表明,链转移剂PeAATP对聚合反应有较好的调控性,所得到的四臂星形聚合物分子量可控、分子量分布较窄,为“活性”聚合反应。
(2)在CuBr/PMDETA催化剂存在条件下,通过N,N-二(2-炔丙氧羰基乙基)-2-羟乙胺(BPHA)与超稀浓度的四臂星形聚合物溶液的“Click”反应,合成“8”形聚合物。用FT-IR、1H NMR、GPC和MALDI-TOF MS对所合成的聚合物进行了表征。FT-IR谱图中2100 cm~(-1)处叠氮基吸收峰消失证明聚合物中叠氮基已经全部反应;1H NMR谱图上在δ= 8.42 ppm处出现新吸收峰表明三咪唑环生成;GPC测试表明成环后聚合物分子量降低,MALDI-TOF MS结果表明反应前后聚合物分子量几乎不变,证明“Click”反应是分子内成环而非分子间缩合。DLS结果表明,“8”形PDMA-b-PNIPAM的临界胶束温度(CMT)比其四臂前驱体低,而形成胶束后胶束的流体力学直径(Dh)也比其四臂前驱体的小。
Cyclic topological polymers including single and multiple cyclic polymers have attracted a growing interest for the past decades as a result of their unique properties comparing with their branched and linear counterparts. Double cyclic polymers, including 8-shaped, theta-shaped and manacle-shaped polymers are an important class of cyclic topological polymers. Among there three double cyclic polymer topologies, the 8-shaped polymer has been investigated the most. But most of the synthetic strategies reported are based on anionic, cationic, or ring-expansion polymerization. The monomers used are limited and rigorous experiment conditions are needed. In this thesis, a series of well defined 8-shaped polymers, including poly(N,N-dimethyl- acrylamide) (PDMA), poly(N-isopropylacrylamide) (PNIPAM) and poly(N,N-di- methylacrylamide)-b-poly(N-isopropylacrylamide) (PDMA-b-PNIPAM) with controll molecular weight and narrow polydispersity were synthesized by the combination of RAFT polymerization and“Click”chemistry.
Firstly, four-arm star polymers with azido groups were prepared by RAFT polymerization using pentaerythritoltetrakis(3-(S-(2-azidoethylacetate)trithiocarbonyl) propanoate) (PeAATP) as the chain transfer agent. It can be concluded from the GPC results that the polymerization is preceded with good control. Then the intramolecular Click ring closure of the four-arm star polymers was conducted under highly dilute conditions, using N,N-bis(2-propargyloxycarbonyl ethyl)-2-hydroxylethyl amine (BPHA) as linker and CuBr/PMDETA as the catalyst, respectively, affording well-defined 8-shaped polymers. FTIR, 1H NMR, GPC, and MS analysis confirmed the complete consumption of azido group in four-arm star polymers and that the coupling reaction proceeded via the intramolecular manner. The self-assembly behavior of 8-shaped PDMA-b-PNIPAM was investigated by DLS. Comparing with their four-arm star precursor, the 8-shaped polymers possesse lower CMT and smaller hydrodynamic diameter (Dh). The difference in self-assembly behaviors between 8-shaped and four-arm star PDMA-b-PNIPAM should be due to the absence of chain ends and stringent restrictions on backbone conformation in the former.
引文
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[1] Schappacher M, Deffieux A. Controlled Synthesis of Bicyclic "Eight-Shaped" Poly(chloroethyl vinyl ether)s[J]. Macromolecules, 1995, 28(8):2629-2636.
[2] Kubo M, Hayashi T, Itoh T. Syntheses of Tadpole- and Eight-Shaped Polystyrenes Using Cyclic Polystyrene as a Building Block[J]. Macromolecules, 1998, 31(4):1053-1057.
[3] Whittaker M R, Goh Y K, Monteiro M J. Synthesis of Monocyclic and Linear Polystyrene Using the Reversible Coupling/Cleavage of Thiol/Disulfide Groups[J]. Macromolecules, 2006, 39(26):9028-9034.
[4] Jia Z, Fu Q, Huang J. Synthesis of Amphiphilic Macrocyclic Graft Copolymer Consisting of a Poly(ethylene oxide) Ring and Multi-Polystyrene Lateral Chains[J]. Macromolecules, 2006, 39(16):5190-5193.
[5] Tezuka Y, Mori K, Oike H. Efficient Synthesis of Cyclic Poly(oxyethylene) by Electrostatic Self-Assembly and Covalent Fixation with Telechelic Precursor Having Cyclic Ammonium Salt Groups[J]. Macromolecules, 2002, 35(14):5707-5711.
[6] Qiu X P, Tanaka F, Winnik F M. Temperature-Induced Phase Transition of Well-Defined Cyclic Poly(N-isopropylacrylamide)s in Aqueous Solution[J]. Macromolecules, 2007, 40(20):7069-7071.
[7] Xu J, Ye J, Liu S. Synthesis of Well-Defined Cyclic Poly(N-isopropylacrylamide) via Click Chemistry and Its Unique Thermal Phase Transition Behavior[J]. Macromolecules, 2007, 40(25):9103-9110.
[8] Shi G Y, Tang X Z, Pan C Y. Tadpole-shaped amphiphilic copolymers prepared via RAFT polymerization and click reaction[J]. Journal of Polymer Science Part A: Polymer Chemistry, 2008, 46(7):2390-2401.
[9] Shi G-Y, Pan C-Y. Synthesis of Well-Defined Figure-of-Eight-Shaped Polymers by a Combination of ATRP and Click Chemistry[J]. Macromolecular Rapid Communications, 2008, 29 (20):1672-1678.
[10] Laurent B A, Grayson S M. An Efficient Route to Well-Defined Macrocyclic Polymers via "Click" Cyclization[J]. Journal of the American Chemical Society, 2006, 128(13): 4238-4239.
[11] Tsarevsky N V, Sumerlin B S, Matyjaszewski K. Step-Growth“Click”Coupling of Telechelic Polymers Prepared by Atom Transfer Radical Polymerization[J]. Macromolecules, 2005, 38(9):3558-3561.
[2] Merrifield R B. Solid Phase Peptide Synthesis. I. The Synthesis of a Tetrapeptide[J]. Journal of the American Chemical Society, 1963, 85(14):2149-2154.
[3] McLeish T. CHEMISTRY: Polymers Without Beginning or End[J]. Science, 2002, 297(5589):2005-2006.
[4] Mayadunne R T A, Jeffery J, Rizzardo E. Living Free Radical Polymerization with Reversible Addition-Fragmentation Chain Transfer (RAFT Polymerization): Approaches to Star Polymers[J]. Macromolecules, 2003, 36(5):1505-1513.
[5] He T, Li D, Zhao B. Synthesis of ABC 3-Miktoarm Star Terpolymers from a Trifunctional Initiator by Combining Ring-Opening Polymerization, Atom Transfer Radical Polymerization, and Nitroxide-Mediated Radical Polymerization[J]. Macromolecules, 2004, 37(9):3128-3135.
[6] Abdollahi H, Mahdavi V. Tautomerization Equilibria in Aqueous Micellar Solutions: A Spectrophotometric and Factor-Analytical Study[J]. Langmuir, 2007, 23(5):2362-2368.
[7] Karayiannis N C, Mavrantzas V G. Hierarchical Modeling of the Dynamics of Polymers with a Nonlinear Molecular Architecture: Calculation of Branch Point Friction and Chain Reptation Time of H-Shaped Polyethylene Melts from Long Molecular Dynamics Simulations[J]. Macromolecules, 2005, 38(20):8583-8596.
[8] Matyjaszewski K. Synthesis of Molecular Brushes by“Grafting onto”Method: Combinationof ATRP and Click Reactions[J]. Journal of the American Chemical Society, 2007, 129(20):6633-6639.
[9] Tang B Z. Hyperbranched Polytriazoles: Click Polymerization, Regioisomeric Structure, Light Emission, and Fluorescent Patterning[J]. Macromolecules, 2008, 41(11):3808-3822.
[10] Kong L Z, Pan C Y. Synthesis and Characterization of Hyperbranched Polymers from the Polymerization of Glycidyl Methacrylate and Styrene Using TiCl as a Catalyst[J]. Macromolecular Chemistry and Physics, 2007, 208(24):2686-2697.
[11] Malkoch M, Schleicher K, Fokin V V. Structurally Diverse Dendritic Libraries: A Highly Efficient Functionalization Approach Using Click Chemistry[J]. Macromolecules, 2005, 38(9):3663-3678.
[12] Angot S, Taton D, Gnanou Y. Amphiphilic Stars and Dendrimer-Like Architectures Based on Poly(Ethylene Oxide) and Polystyrene[J]. Macromolecules, 2000, 33(15):5418-5426.
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[1] Schappacher M, Deffieux A. Controlled Synthesis of Bicyclic "Eight-Shaped" Poly(chloroethyl vinyl ether)s[J]. Macromolecules, 1995, 28(8):2629-2636.
[2] Kubo M, Hayashi T, Itoh T. Syntheses of Tadpole- and Eight-Shaped Polystyrenes Using Cyclic Polystyrene as a Building Block[J]. Macromolecules, 1998, 31(4):1053-1057.
[3] Whittaker M R, Goh Y K, Monteiro M J. Synthesis of Monocyclic and Linear Polystyrene Using the Reversible Coupling/Cleavage of Thiol/Disulfide Groups[J]. Macromolecules, 2006, 39(26):9028-9034.
[4] Jia Z, Fu Q, Huang J. Synthesis of Amphiphilic Macrocyclic Graft Copolymer Consisting of a Poly(ethylene oxide) Ring and Multi-Polystyrene Lateral Chains[J]. Macromolecules, 2006, 39(16):5190-5193.
[5] Tezuka Y, Mori K, Oike H. Efficient Synthesis of Cyclic Poly(oxyethylene) by Electrostatic Self-Assembly and Covalent Fixation with Telechelic Precursor Having Cyclic Ammonium Salt Groups[J]. Macromolecules, 2002, 35(14):5707-5711.
[6] Qiu X P, Tanaka F, Winnik F M. Temperature-Induced Phase Transition of Well-Defined Cyclic Poly(N-isopropylacrylamide)s in Aqueous Solution[J]. Macromolecules, 2007, 40(20):7069-7071.
[7] Xu J, Ye J, Liu S. Synthesis of Well-Defined Cyclic Poly(N-isopropylacrylamide) via Click Chemistry and Its Unique Thermal Phase Transition Behavior[J]. Macromolecules, 2007, 40(25):9103-9110.
[8] Shi G Y, Tang X Z, Pan C Y. Tadpole-shaped amphiphilic copolymers prepared via RAFT polymerization and click reaction[J]. Journal of Polymer Science Part A: Polymer Chemistry, 2008, 46(7):2390-2401.
[9] Shi G-Y, Pan C-Y. Synthesis of Well-Defined Figure-of-Eight-Shaped Polymers by a Combination of ATRP and Click Chemistry[J]. Macromolecular Rapid Communications, 2008, 29 (20):1672-1678.
[10] Laurent B A, Grayson S M. An Efficient Route to Well-Defined Macrocyclic Polymers via "Click" Cyclization[J]. Journal of the American Chemical Society, 2006, 128(13): 4238-4239.
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