化学酶法合成嵌段共聚物及其自组装的研究
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摘要
本论文通过酶促聚合方法和ATRP聚合方法相结合制备嵌段共聚物。用双羟基聚乙二醇引发了聚己内酯的酶促开环聚合,合成了羟基封端的聚酯PCL-b-PEG-b-PCL。通过端基官能化修饰这个羟基封端的聚酯得到了α-溴代物封端的大分子引发剂,先用这个引发剂引发甲基丙烯酸六氟丁酯ATRP反应合成了PHFMA-b-PCL-b-PEG-b-PCL-b-PHFMA。然后用合成的引发剂引发了GMA的ATRP合成了PGMA-b-PCL-b-PEG-b-PCL-b-PGMA。通过核磁和红外光谱分析证明了大分子引发剂和五嵌段共聚物的结构。五嵌段共聚物的GPC分析表明这种合成方法的可行,反应动力学分析证明了聚合方法是活性可控的。通过动态光散射方法测试了胶束的直径。研究了五嵌段共聚物在水中的自组装行为。
为了扩展化学酶聚合反应所得产物的结构种类,我们合成了规整的Y-型双亲嵌段共聚物。首先,在Novozyme 435酶催化下,甲醇引发己内酯开环聚合,合成一端为CH3O-封端,另一端为OH封端的PCL聚酯。通过PCL聚酯和2,2-二氯代乙酰氯的酯化反应合成大分子引发剂,接着用合成的大分子引发剂引发了GMA/St的ATRP聚合,合成新型的Y-型嵌段共聚物PCL-b-(PGMA)2和PCL-b-(PSt)2。聚合物的结构通过NMR、GPC和IR表征,并且研究了它们的在水溶液中组装。研究表明,Y-型嵌段共聚物自组装的形貌与聚合物的组成和共聚物的起始浓度有关。
作为另一种重要的生物酶聚合方法,酶促缩聚反应在聚合物合成领域的工业应用和基础研究发展迅速。我们利用酶促缩聚反应与ATRP反应相结合,用两种合成路线合成了P(TCE-10-HD)-b-PGMA。具体方法如下,第一种合成路线,合成方法分为三个步骤:首先,通过2,2,2-三氯乙醇(TCE)与10-羟基癸酸(10-HD)之间的有机成酯缩合反应合成ω-羟基酯(10-羟基癸酸三氯乙酯TCE-10-HD);然后,在固定化酶Novozyme 435催化下,经过ω-羟基酯的酶促自缩聚反应获得了端头带有三氯甲基的ATRP大分子引发剂P(TCE-10-HD)-CCl3;最后,利用合成的引发剂实现了功能单体GMA的ATRP反应,成功合成了P(TCE-10-HD)-b-PGMA。利用NMR、GPC和IR分析证明了嵌段共聚物的结构。另外,研究了嵌段共聚物在水溶液中的自组装行为,嵌段共聚物胶束为纳米级的、并具有均一的尺寸。第二种合成路线分为两步:我们用了一种新的方法,将2,2,2-三氯乙醇加入10-羟基癸酸酶促缩聚的反应体系中,仅用一步反应就得到了P(TCE-10-HD)-CCl3,取代了以前所用的两步合成法。然后用合成的引发剂引发了GMA的ATRP反应合成了P(TCE-10-HD)-b-PGMA,并且证明这种聚合方法是简便可行的。
Block copolymers has been received great interest because of its unique properties such as impact-resistant plastics, different phase behavior, thermoplastic elastomers, variety of morphologies, polymeric emulsifiers, sol-gel states, and gas permeation membranes.
In the first section of Chapter 1, we enumerated the virtues of biocatalyst enzyme and reviewed enzymatic polymerization in organic media. At the same time, chemical polymerizations (e.g., ATRP) appeared in chemoenzymatic synthesis reported previously were summarized in brief. Subsequently, we introduced in detail chemoenzymatic polymerization given in previous reports. More importantly, we sum up the strategies, synthesis method, functionality and potential application of chemoenzymatic synthesis related to ATRP.
In chapter 2, symmetric linear pentablock copolymers consisting of ploy(ethylene glycol)(PEG), polycaprolactone (PCL) and 2,2,3,4,4,4-Hexafluorobutyl methacrylate (PHFMA) and GMA was synthesized by means of the enzymatic ring-opened polymerization(eROP) combined with atom transfer radical polymerization(ATRP). Dihydroxyl PEG initiated eROP ofε-CL to synthesize the hydroxyl group terminated polyester PCL-b-PEG-b-PCL. Theα-bromoester terminated macroinitiator Br-PCL-b-PEG-b-PCL-Br was obtained in the subsequent modification of end hydroxyl groups that was suitable for block ATRP of fluorinated monomer (PHFMA) and GMA. Pentablock copolymers PHFMA-b-PCL-b-PEG-b-PCL-b-PHFMA and PGMA-b-PCL-b-PEG-b-PCL-b-
PGMA was obtained via the further ATRP. 1H NMR and IR measurements were used to confirm the macroinitiator and architecture of the pentablock copolymer .GPC testifies that this method is feasible and its kinetics analysis indicates a living/controlled radical polymerization. The micelle diameter was investigated by virtue of dynamic light scattering(DLS).The self-assembly behavior of the pentablock copolymer was investigated in aqueous media.
In chapter 3, Novel Y-shaped block copolymers were synthesized by using dichloropolyester, initially synthesized by ROP of PCL, as macroinitiators for the ATRP of GMA. The structures of all the polymer products were well characterized by means of NMR, GPC, and IR measurement. The combination of these two processes affords well-defined copolymers of a wide array of compositions. The PCL: PGMA ratios of each constituting block significantly influenced the properties of the copolymers, especially micellization properties. These copolymers represented a unique set of PCL/PGMA analogous Y-shaped copolymers, of which the self-assembling behavior in aqueous media had been studied in detail. Self-assembling of Y-shaped block copolymers led to the formation of different morphologies. The morphology of these Y-shaped block copolymers examined by AFM showed various morphologies such as normal spherical micelles, vesicles, lamellae, and large compound micelles (LCMs). Moreover, it was found that both the copolymer composition and the copolymer concentration in THF had a great influence on the morphologies of the aggregates. In addition, experiments aimed at the effect of the solvent nature, temperature, and storage time of the morphologies are under way.
The ATRP macroiniitiator effectively initiated ATRP of styrene with CuCl/2,2`-bipyridine as the catalyst system. Linear first-order kinetics, linearly increasing molecular weight with conversion, and low polydispersities (less than 1.29) were observed in this process. The structures and composition of the Y-shaped copolymer were well characterized by means of NMR, IR and GPC measurement. DSC analysis showed that the crystallinity of the copolymer decreased with the introduction of the PSt block. Chemoenzymatic synthesis of Y-shaped block copolymer is a novel technique, which not only allows the variation of the polymer composition by adjusting the ratios between the macroinitiator and monomer, but also can control the structure of polymer exactly. In addition, the research for the morphology of Y-shaped block copolymers is in progress. In Chapter 4, our group proposed a simple strategy for a novel idea, i.e.
enzymatic polycondensation was combined with ATRP to inspect further the compatibility between biocatalytic technique and chemocatalytic technique. A novelω-hydroxyester 2,2,2-trichloroethyl 10-hydroxydecanate P(TCE-10-HD) was firstly synthesized and used in eSCP to obtain linear polyester P(TCE-10-HD), whose terminal was occupied by the ATRP initiating groups, -CCl3. The macroinitiator started the ATRP of St and GMA to prepare diblock copolymer P(TCE-10-HD)-b-PGMA. The introduce of eSCP expanded the category of enzymatic polymerization in chemoenzymatic polymerization, which inaugurated a new research domain. Well-defined diblock copolymer poly (2, 2, 2-trichloroethanol 10-hydroxydecanate)-block-poly (glycidyl methacrylate) [P (TCE-10-HD)-b-PGMA] was obtained by combining the enzymatic condensation polymerization and ATRP. P (TCE-10-HD) was firstly prepared by enzymatic condensation polymerization of 10-HD and, within the same step, TCE. This -CCl3 terminated polyester permitted the subsequent ATRP of GMA without other steps. The structures of the polymers were characterized by NMR, FTIR. The kinetic results were measured by GPC. The self-assembly behavior of the amphiphilic diblock copolymer was also investigated. The morphology of the assembly particles were studied by AFM, TEM and SEM.
为了扩展化学酶聚合反应所得产物的结构种类,我们合成了规整的Y-型双亲嵌段共聚物。首先,在Novozyme 435酶催化下,甲醇引发己内酯开环聚合,合成一端为CH3O-封端,另一端为OH封端的PCL聚酯。通过PCL聚酯和2,2-二氯代乙酰氯的酯化反应合成大分子引发剂,接着用合成的大分子引发剂引发了GMA/St的ATRP聚合,合成新型的Y-型嵌段共聚物PCL-b-(PGMA)2和PCL-b-(PSt)2。聚合物的结构通过NMR、GPC和IR表征,并且研究了它们的在水溶液中组装。研究表明,Y-型嵌段共聚物自组装的形貌与聚合物的组成和共聚物的起始浓度有关。
作为另一种重要的生物酶聚合方法,酶促缩聚反应在聚合物合成领域的工业应用和基础研究发展迅速。我们利用酶促缩聚反应与ATRP反应相结合,用两种合成路线合成了P(TCE-10-HD)-b-PGMA。具体方法如下,第一种合成路线,合成方法分为三个步骤:首先,通过2,2,2-三氯乙醇(TCE)与10-羟基癸酸(10-HD)之间的有机成酯缩合反应合成ω-羟基酯(10-羟基癸酸三氯乙酯TCE-10-HD);然后,在固定化酶Novozyme 435催化下,经过ω-羟基酯的酶促自缩聚反应获得了端头带有三氯甲基的ATRP大分子引发剂P(TCE-10-HD)-CCl3;最后,利用合成的引发剂实现了功能单体GMA的ATRP反应,成功合成了P(TCE-10-HD)-b-PGMA。利用NMR、GPC和IR分析证明了嵌段共聚物的结构。另外,研究了嵌段共聚物在水溶液中的自组装行为,嵌段共聚物胶束为纳米级的、并具有均一的尺寸。第二种合成路线分为两步:我们用了一种新的方法,将2,2,2-三氯乙醇加入10-羟基癸酸酶促缩聚的反应体系中,仅用一步反应就得到了P(TCE-10-HD)-CCl3,取代了以前所用的两步合成法。然后用合成的引发剂引发了GMA的ATRP反应合成了P(TCE-10-HD)-b-PGMA,并且证明这种聚合方法是简便可行的。
Block copolymers has been received great interest because of its unique properties such as impact-resistant plastics, different phase behavior, thermoplastic elastomers, variety of morphologies, polymeric emulsifiers, sol-gel states, and gas permeation membranes.
In the first section of Chapter 1, we enumerated the virtues of biocatalyst enzyme and reviewed enzymatic polymerization in organic media. At the same time, chemical polymerizations (e.g., ATRP) appeared in chemoenzymatic synthesis reported previously were summarized in brief. Subsequently, we introduced in detail chemoenzymatic polymerization given in previous reports. More importantly, we sum up the strategies, synthesis method, functionality and potential application of chemoenzymatic synthesis related to ATRP.
In chapter 2, symmetric linear pentablock copolymers consisting of ploy(ethylene glycol)(PEG), polycaprolactone (PCL) and 2,2,3,4,4,4-Hexafluorobutyl methacrylate (PHFMA) and GMA was synthesized by means of the enzymatic ring-opened polymerization(eROP) combined with atom transfer radical polymerization(ATRP). Dihydroxyl PEG initiated eROP ofε-CL to synthesize the hydroxyl group terminated polyester PCL-b-PEG-b-PCL. Theα-bromoester terminated macroinitiator Br-PCL-b-PEG-b-PCL-Br was obtained in the subsequent modification of end hydroxyl groups that was suitable for block ATRP of fluorinated monomer (PHFMA) and GMA. Pentablock copolymers PHFMA-b-PCL-b-PEG-b-PCL-b-PHFMA and PGMA-b-PCL-b-PEG-b-PCL-b-
PGMA was obtained via the further ATRP. 1H NMR and IR measurements were used to confirm the macroinitiator and architecture of the pentablock copolymer .GPC testifies that this method is feasible and its kinetics analysis indicates a living/controlled radical polymerization. The micelle diameter was investigated by virtue of dynamic light scattering(DLS).The self-assembly behavior of the pentablock copolymer was investigated in aqueous media.
In chapter 3, Novel Y-shaped block copolymers were synthesized by using dichloropolyester, initially synthesized by ROP of PCL, as macroinitiators for the ATRP of GMA. The structures of all the polymer products were well characterized by means of NMR, GPC, and IR measurement. The combination of these two processes affords well-defined copolymers of a wide array of compositions. The PCL: PGMA ratios of each constituting block significantly influenced the properties of the copolymers, especially micellization properties. These copolymers represented a unique set of PCL/PGMA analogous Y-shaped copolymers, of which the self-assembling behavior in aqueous media had been studied in detail. Self-assembling of Y-shaped block copolymers led to the formation of different morphologies. The morphology of these Y-shaped block copolymers examined by AFM showed various morphologies such as normal spherical micelles, vesicles, lamellae, and large compound micelles (LCMs). Moreover, it was found that both the copolymer composition and the copolymer concentration in THF had a great influence on the morphologies of the aggregates. In addition, experiments aimed at the effect of the solvent nature, temperature, and storage time of the morphologies are under way.
The ATRP macroiniitiator effectively initiated ATRP of styrene with CuCl/2,2`-bipyridine as the catalyst system. Linear first-order kinetics, linearly increasing molecular weight with conversion, and low polydispersities (less than 1.29) were observed in this process. The structures and composition of the Y-shaped copolymer were well characterized by means of NMR, IR and GPC measurement. DSC analysis showed that the crystallinity of the copolymer decreased with the introduction of the PSt block. Chemoenzymatic synthesis of Y-shaped block copolymer is a novel technique, which not only allows the variation of the polymer composition by adjusting the ratios between the macroinitiator and monomer, but also can control the structure of polymer exactly. In addition, the research for the morphology of Y-shaped block copolymers is in progress. In Chapter 4, our group proposed a simple strategy for a novel idea, i.e.
enzymatic polycondensation was combined with ATRP to inspect further the compatibility between biocatalytic technique and chemocatalytic technique. A novelω-hydroxyester 2,2,2-trichloroethyl 10-hydroxydecanate P(TCE-10-HD) was firstly synthesized and used in eSCP to obtain linear polyester P(TCE-10-HD), whose terminal was occupied by the ATRP initiating groups, -CCl3. The macroinitiator started the ATRP of St and GMA to prepare diblock copolymer P(TCE-10-HD)-b-PGMA. The introduce of eSCP expanded the category of enzymatic polymerization in chemoenzymatic polymerization, which inaugurated a new research domain. Well-defined diblock copolymer poly (2, 2, 2-trichloroethanol 10-hydroxydecanate)-block-poly (glycidyl methacrylate) [P (TCE-10-HD)-b-PGMA] was obtained by combining the enzymatic condensation polymerization and ATRP. P (TCE-10-HD) was firstly prepared by enzymatic condensation polymerization of 10-HD and, within the same step, TCE. This -CCl3 terminated polyester permitted the subsequent ATRP of GMA without other steps. The structures of the polymers were characterized by NMR, FTIR. The kinetic results were measured by GPC. The self-assembly behavior of the amphiphilic diblock copolymer was also investigated. The morphology of the assembly particles were studied by AFM, TEM and SEM.
引文
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[2] Gross, R. A.; Kumar, A.; Kalra, B. Polymer synthesis by in vitro enzyme catalysis. Chem Rev 2001, 101, 2097-2124
[3] Bisht, K. S.; Deng, F.; Gross, R. A.; Kaplan, D. L.; Swift, G. J. Am. Chem. Soc. 1998, 120, 1363-1367
[4] Srivastava, R. K.; Albertsson, A. High-molecular-weight poly (1,5-dioxepan-2-one) via enzyme-catalyzed ring-opening polymerization. J. Polym. Sci. Part A: Polym. Chem. 2005, 43, 4206-4216
[5] Wallace, J. S.; Morrow, C. J. Biocatalytic synthesis of polymers. II. Preparation of [AA-BB]x polyesters by porcine pancreatic lipase catalyzed transesterification in anhydrous, low polarity organic solvents. J. Polym. Sci. Part A: Polym. Chem. 1989, 27, 3271-3284
[6] Mahapatro, A.; Kumar, A.; Gross, R. A. Mild, solvent-free hydroxyl acid polycondensations catalyzed by canadida Antarctica lipase B. Biomacromolecules 2004, 5, 62-68
[7] Mahapatro, A.; Kalra, B.; Kumar, A.; Gross, R. A. Lipase-catalyzed polycondensations: effect of substrates and solvent on chain formation, dispersity and end-group structure. Biomacromolecules 2003, 4, 544-551
[8] Mahapatro, A.; Kumar, A.; Kalra, B.; Gross, R. A. Solvent-free adipic acid-1, 8-octanediol condensation polymerizations catalyzed by candida antartica lipase B. Macromolecules 2004, 37, 35-40
[9] Knani, D.; Gutman, A. L.; Kohn, D. H. Enzymatic polyesterification in organic media. Enzyme-catalyzed synthesis of linear polyesters. I. Condensation polymerization of liner hydroxyester. II. Ring0opening polymerization of caprolactone. J. Polym. Sci. Part A: Polym. Chem. 1993, 31, 1221-1232
[10] He, F.; Li, S.; Vert, M.; Zhou, R. Enzyme-catalyzed polymerization and degradation of copolymers prepared from caprolactone and poly(ethylene glycol). Polymer 2003, 44, 5145-5151
[11] Panova, A. A.; Kaplan, D. L. Mechanistic limitations in the synthesis of poyesters by lipase-catalyzed ring-opening polymerization. Biotechnol. Bioeng. 2003, 84, 103-113
[12] Skaria, S.; Smet, M.; Frey, H. Enzyme-catalyzed synthesis of hyperbranched Aliphatic polyesters. Macromol. Rapid Commun. 2002, 23, 292-296
[13] Kumar, R.; Chen, M.; Parmar, V. S.; Samuelson, L. A.; Kumar, J.; Nicolosi, R.; Yoganathan, S.; Watterson, A. C. J. Am. Chem. Soc. 2004, 126, 10640.
[14] Kobayashi, S.; Uyama, H.; Kimura, S. Chem. Rev. 2001, 101, 3793.
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