分散聚合两步法制备壳交联聚合物微球及自模板制备空心球
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摘要
空心微球具有密度较低、比表面积较高、渗透性好等特点,内部空心结构可以容纳较多的物质,这种微观结构使其作为功能材料在化妆品、涂料、印刷、造纸、药物缓释及催化剂载体等领域有着广泛应用,聚合物空心球作为其中的一大类,同样具有上述所有的性质。
本文采用一种新的分散聚合的方法制备聚苯乙烯纳米尺寸的空心球,分散聚合两步加料法,在单体苯乙烯(St)转化率达80%以上时加入交联剂二乙烯基苯(DVB),以未交联内核自身为模板,制备了PSt核-P(St-DVB)壳(壳交联)结构微球。进一步,使用PSt的良溶剂THF将未交联内核溶出后,制得了结构规整的空心聚合物微球。采用扫描电镜(SEM)及透射电镜(TEM)观察了所得核-壳、空心球的形貌,探讨了核-壳聚合物微球制备过程的反应条件：引发剂用量、单体浓度及交联剂用量对最终所得空心球形貌的影响。结果表明：增大引发剂用量,微球内核聚合物的分子量增大,内核不易溶出；增大起始单体浓度,所得空心球易破裂,刚度下降,单体浓度过低可使交联层致密,不利于内核聚合物溶出,得到蜂窝状空球；交联剂用量增加,所得空心球的刚度和壁厚增加。
微球的结构规整、壁厚均匀,直径约为800nm,通过调整单体浓度、引发剂的量,DVB的加入时间、DVB的量、溶解时间等因素可以影响空心微球的壳层厚度、均匀度、硬度等,其中单体浓度和DVB的加入时间影响最大。
与传统的模板法相比,本方法不需要单独的步骤制备模板,反应具有连续性,同时模板易去除,具有操作简单,球体厚度可控等优点。
In this paper, monodisperse core (PSt)-shell (cross-linked P(St-DVB)) microspheres were prepared firstly by a two-stage dispersion polymerization in which DVB was charged into reaction system after monomer conversion high up to 80%. The cross-linking mainly took place at the surface of PS particles to form shell layer. Subsequently, hollow particles composed of cross-linked P(St-DVB) were prepared by dealing the core-shell microspheres with a solvent of THF in which the core polymer was dissolved and removed.
The morphology of the generated core-shell or hollow structures was observed by SEM and TEM. The influences of some parameters such as the initiator concentration, monomer content and crosslinker amount applied in the dispersion polymerization on the morphology of final hollow particles were investigated. The results indicated that perfect hollow particles could not be readily produced if greater concentration of initiator was used in the first dispersion polymerization, owning to the somewhat difficulty in removing the core polymer with high molecular weight. High monomer content presented in the polymerization could lead to the less rigidity of the final hollow particles, while the low monomer content could bring about densely crosslinked shell, and thus allow some core polymer remained in THF treatment, resulting in the formation of honeycomb particles. Increasing the amount of crosslinker employed in dispersion polymerization, hollow particles with proper thickness and rigidity were fabricated finally.
本文采用一种新的分散聚合的方法制备聚苯乙烯纳米尺寸的空心球,分散聚合两步加料法,在单体苯乙烯(St)转化率达80%以上时加入交联剂二乙烯基苯(DVB),以未交联内核自身为模板,制备了PSt核-P(St-DVB)壳(壳交联)结构微球。进一步,使用PSt的良溶剂THF将未交联内核溶出后,制得了结构规整的空心聚合物微球。采用扫描电镜(SEM)及透射电镜(TEM)观察了所得核-壳、空心球的形貌,探讨了核-壳聚合物微球制备过程的反应条件：引发剂用量、单体浓度及交联剂用量对最终所得空心球形貌的影响。结果表明：增大引发剂用量,微球内核聚合物的分子量增大,内核不易溶出；增大起始单体浓度,所得空心球易破裂,刚度下降,单体浓度过低可使交联层致密,不利于内核聚合物溶出,得到蜂窝状空球；交联剂用量增加,所得空心球的刚度和壁厚增加。
微球的结构规整、壁厚均匀,直径约为800nm,通过调整单体浓度、引发剂的量,DVB的加入时间、DVB的量、溶解时间等因素可以影响空心微球的壳层厚度、均匀度、硬度等,其中单体浓度和DVB的加入时间影响最大。
与传统的模板法相比,本方法不需要单独的步骤制备模板,反应具有连续性,同时模板易去除,具有操作简单,球体厚度可控等优点。
In this paper, monodisperse core (PSt)-shell (cross-linked P(St-DVB)) microspheres were prepared firstly by a two-stage dispersion polymerization in which DVB was charged into reaction system after monomer conversion high up to 80%. The cross-linking mainly took place at the surface of PS particles to form shell layer. Subsequently, hollow particles composed of cross-linked P(St-DVB) were prepared by dealing the core-shell microspheres with a solvent of THF in which the core polymer was dissolved and removed.
The morphology of the generated core-shell or hollow structures was observed by SEM and TEM. The influences of some parameters such as the initiator concentration, monomer content and crosslinker amount applied in the dispersion polymerization on the morphology of final hollow particles were investigated. The results indicated that perfect hollow particles could not be readily produced if greater concentration of initiator was used in the first dispersion polymerization, owning to the somewhat difficulty in removing the core polymer with high molecular weight. High monomer content presented in the polymerization could lead to the less rigidity of the final hollow particles, while the low monomer content could bring about densely crosslinked shell, and thus allow some core polymer remained in THF treatment, resulting in the formation of honeycomb particles. Increasing the amount of crosslinker employed in dispersion polymerization, hollow particles with proper thickness and rigidity were fabricated finally.
引文
[1]Vanderhoff J W, Bradford E R. Polymer Colloid [M]. New York:Plenum Press,1971.
[2]Vanderhoff J W, El-Aasser M S, Micale F J, Sudol E D, Tseng CM, Silwanowicz A, Kornfeld D M, Vicente F A. Preparation of large-particle-size monodisperse latexes in space:polymerization kinetics and process development[J]. Journal of Dispersion Science and Technology,1984,5:231-246.
[3]Ugelstad J, Mork P C, Kaggerud K H, El-Iingsen T, Berge A. Swelling of oligomer-polymer particles. New methods of preparation[J]. Advances in Colloid and Interface Science,1980,13:101-140.
[4]Barrett KEG, Ed. Dispersion Polymerization in Organic Media[M]. New York:Wiley, 1975.
[5]Almog Y, Reich S, Levy M. Monodisperse polymeric spheres in the micron size range by a single step process[J].British polymer journal,1982,14:131-136.
[6]Tseng C M, Lu Y Y, El-Aasser M S, Vanderhoff J W. Uniform Polymer Particles by Dispersion Polymerization in Alcohol[J]. Journal of Polymer Science Part A:Polymer Chemistry,1986,24:2995-3007.
[7]Ober C K, Lok K P, Hair M L. Monodispersed, micron-sized polystyrene particles by dispersion polymerization [J]. Journal of Polymer Science:Polymer Letters Edition,1985, 23:103-108.
[8]Kawaguchi S, Mitchell A. Winnik, Koichi Ito. Dispersion Copolymerization of n-Butyl Methacrylate with Poly(ethylene oxide) Macromonomers in Methanol-Water. Comparison of Experiment with Theory[J]. Macromolecules,1995,28:1159-1166.
[9]Paine A J, Luymes W, McNulty J. Dispersion polymerization of styrene in polar solvents. 6. Influence of reaction parameters on particle size and molecular weight in poly(N-vinylpyrrolidone)-stabilized reactions [J]. Macromolecules,1990,23:3104-3109.
[10]Lu Y Y, El-Aasser M S, Vanderhoff J W. Dispersion polymerization of styrene in ethanol: Monomer partitioning behavior and locus of polymerization[J]. Journal of Polymer Science Part B:Polymer Physics,1988,26:1187-1203.
[11]Kawaguchi H. Functional polymer microspheres[J]. Progress in Polymer Science,2000, 25:1171-1210.
[12]Barret K E J. Dispersion polymerisation in organic media[J]. British Polymer Journal, 1973,5:259-271.
[13]Shen S, Sudol E D, El-Aasser M S. Control of particle size in dispersion polymerization of methyl methacrylate[J]. Journal of Polymer Science Part A:Polymer Chemistry,1993,31: 1393-1402.
[14]Prochazka O, Stejskal J. Spherical particles obtained by dispersion polymerization:model calculations[J]. Polymer,1992,33:3658-3663.
[15]Paine A J. Dispersion polymerization of styrene in polar solvents.7. A simple mechanistic model to predict particle size[J]. Macromolecules,1990,23:3109-3117.
[16]Y. Y. Lu, Ph.D. dissertation, Lehigh University, Bethlehem, PA,1988.
[17]Shen S, Sudol E D, El-Aasser M S. Dispersion polymerization of methyl methacrylate: Mechanism of particle formation[J]. Journal of Polymer Science Part A:Polymer Chemistry,1994,32:1087-1100.
[18]王占丽,刘莲英,邓建平等.分散聚合制备单分散阳离子型聚苯乙烯微球[J].北京化工大学学报：自然科学版,2007,34(1)：39-43.
[19]赵庆美,曾黎明.中空聚合物微粒制备方法研究进展[J].现代涂料与涂装,2008,11：3-6.
[20]Kowalski et al. US Patents,1984:4427836.
[21]Okubo M, Konishi Y, Minami H[J]. Colloid Polymer Science,1998,276:638-642.
[22]Konishi Y, Okubo M, Minami H[J]. Colloid Polymer Science,2003,281:123-129.
[23]Okubo M, Konishi Y, Inohara T[J]. Journal of Applied Polymer Science,2002,86(5): 1087-1091.
[24]Minami H, Kobayashi H, Okubo M[J]. Langmuir,2005,21:5655-5658.
[25]Kim B S, Kim J W, Suh K D[J]. Applied Polymer Science,2000,76:38-44.
[26]O'Brien D F,Armitage B,Benedicto A, Bennett D E, Lamparski H G, Lee Y S, Srisiri W, Sisson T M. Polymerization of Preformed Self-Organized Assemblies [J]. Accounts of Chemical Research,1998,31:861-868.
[27]刘鹏,田军,刘维民.空心聚合物纳米球研究进展[J].化工进展,2004(1)：15-20.
[28]Decher G, Hong J D. Buildup of ultrathin multilayer films by a selfassembly process.1. consecutive adsorption anionic and cationic bipolar amphiphiles on charged surfaces [J]. Makromol Chem Makromol Symp,1991,46:321-327.
[29]王虹,廖学红.空心微球结构材料的制备与应用[J].纳米材料与结构,2006,10：470-475.
[30]张萍,冯年平,武培怡.聚合物空心纳米球及其在药学领域的应用[J].药学进展,2005,30：350-352.
[31]Caruso F. Chem. Hollow Capsule Processing through Colloidal Templating and Self-Assembly [J]. Chemistry-A European Journal.2000,6 (3):413-419.
[32]Kim S W, Lee W Y, Hyeon T. Fabrication of Hollow Palladium Spheres and Their Successful Application to the Recyclable Heterogeneous Catalyst for Suzuki Coupling Reactions [J]. Journal of the American Chemical Society,2002,124 (26):7642-7643.
[33]Shchukin D G, Radtchenko IL, Sukhorukov G B. Synthesis of Nanosized Magnetic Ferrite Particles Inside Hollow Polyelectrolyte Capsules [J]. Journal of Physical Chemistry B,2003,107 (1):86-90.
[34]Shchukin D G, Radtchenko IL, Sukhorukov GB. Micron-scale hollow polyelectrolyte capsules with nanosized magnetic Fe3O4 inside [J]. Materials Letters,2003,57:1743-1747.
[35]Dahne L, Leporatti S, Donath E, Mohwald H. Fabrication of Micro Reaction Cages with Tailored Properties [J]. Journal of the American Chemical Society,2001,123:5431-5436.
[36]Antipov A, Shchukin D, Fedutik Y, Zanaveskina I, Klechkovskaya V, Sukhorukov D, Mohwald H. Urease-Catalyzed Carbonate Precipitation inside the Restricted Volume of Polyelectrolyte Capsules [J]. Macromolecular Rapid Communications,2003,24:274-277.
[38]S, Nemanick EJ, Lewis NS. Electrochemical polymerization of aniline monomers infiltrated into well-ordered truncated eggshell structures of polyelectrolyte multilayers [J].
Langmuir,2004,20(2):19-26.
[39]Seiner J A, Microvoids as Pigments. A Review [J]. Industrial and Engineering Chemistry Production Research.1978(17):302-317.
[40]Brown T. Relationship Between Hollow Sphere Pigment Geometry and Optical Performance of Finished Paper Coatings [C].TAPPI Proceedings 1991 Coating Conference,1991,pp.113-212.
[41]Han S, Shi X, Zhou F. Polyelectrolyte hollow sphere lithographic patterning of surfaces: construction of 2-dimensional well-ordered metal arrays [J]. Nano Letters,2002,2: 97-100.
[42]Nemanick E J, Lewis N S. Electrochemical polymerization of aniline monomers infiltrated into well-ordered truncated eggshell structures of polyelectrolyte multilayers [J]. Langmuir,2004,20(2):19-26.
[43]Shi X Y, Shen M W, Mohwald H. Polyelectrolyte multilayer nanoreactors toward the synthesis of diverse nanostructured materials [J]. Progress in Polymer Science,2004,29: 987-1019.
[44]Baumeister E, Klaeger S. Advanced New Lightweight Materials:Hollow-Sphere Composites (HSCs) for Mechanical Engineering Applications [J]. Advanced Engineering Materials,2003,5(9):673-677.
[45]Huang J, Xie Y, Li B, Liu Y, Qian Y, Zhang S. In-Situ Source-Template-Interface Reaction Route to Semiconductor CdS Submicrometer Hollow Spheres [J]. Advanced Materials,2000,12:808-811.
[46]Caruso F, Shi X Y, Caruso R A, A SuSha. Hollow Titania Spheres from Layered Precursor Deposition on Sacrificial Colloidal Core Particles [J]. Advanced Materials, 2001,13(10):740-743.
[47]阚成友,洪曼青,孔祥正,林润雄,焦书科.核壳结构聚合物复合粒子的合成与表征[J].化工科技,1999,7(2)：1-4.
[48]Barrett K E J, Thomas H R. Kinetics of dispersion polymerization of soluble monomers. Ⅰ. Methyl methacrylate [J]. Journal of Polymer Science Part A:Polymer Chemistry,1969,7: 2621-2650.
[49]Okubo M, Konishi Y, Inohara T, Minami H. Production of Hollow Polymer Particles by Suspension Polymerizations for Ethylene Glycol Dimethacrylate/Toluene Droplets Dissolving Styrene-Methyl Methacrylate Copolymers[J]. Journal of Applied Polymer Science,2002,86:1087-1091.
[50]Kobayashi H, Miyanaga E, Okubo M. Preparation of Multihollow Polymer Particles by Seeded Emulsion Polymerization Using Seed Particles with Incorporated Nonionic Emulsifier[J]. Langmuir,2007,23:8703-8708.
[51]Shen S, Sudol E D, El-Aasser M S. Control of particle size in dispersion polymerization of methyl methacrylate [J]. Journal of Polymer Science Part A:Polymer Chemistry,1993, 31:1393-1402
[52]Adams M E, Russell G T, Casey B S, Gilbert R G, Napper D H. Bimolecular Termination Events in the Seeded Emulsion Polymerization of Styrene[J]. Macromolecules,1990,23: 4624-4634.
[2]Vanderhoff J W, El-Aasser M S, Micale F J, Sudol E D, Tseng CM, Silwanowicz A, Kornfeld D M, Vicente F A. Preparation of large-particle-size monodisperse latexes in space:polymerization kinetics and process development[J]. Journal of Dispersion Science and Technology,1984,5:231-246.
[3]Ugelstad J, Mork P C, Kaggerud K H, El-Iingsen T, Berge A. Swelling of oligomer-polymer particles. New methods of preparation[J]. Advances in Colloid and Interface Science,1980,13:101-140.
[4]Barrett KEG, Ed. Dispersion Polymerization in Organic Media[M]. New York:Wiley, 1975.
[5]Almog Y, Reich S, Levy M. Monodisperse polymeric spheres in the micron size range by a single step process[J].British polymer journal,1982,14:131-136.
[6]Tseng C M, Lu Y Y, El-Aasser M S, Vanderhoff J W. Uniform Polymer Particles by Dispersion Polymerization in Alcohol[J]. Journal of Polymer Science Part A:Polymer Chemistry,1986,24:2995-3007.
[7]Ober C K, Lok K P, Hair M L. Monodispersed, micron-sized polystyrene particles by dispersion polymerization [J]. Journal of Polymer Science:Polymer Letters Edition,1985, 23:103-108.
[8]Kawaguchi S, Mitchell A. Winnik, Koichi Ito. Dispersion Copolymerization of n-Butyl Methacrylate with Poly(ethylene oxide) Macromonomers in Methanol-Water. Comparison of Experiment with Theory[J]. Macromolecules,1995,28:1159-1166.
[9]Paine A J, Luymes W, McNulty J. Dispersion polymerization of styrene in polar solvents. 6. Influence of reaction parameters on particle size and molecular weight in poly(N-vinylpyrrolidone)-stabilized reactions [J]. Macromolecules,1990,23:3104-3109.
[10]Lu Y Y, El-Aasser M S, Vanderhoff J W. Dispersion polymerization of styrene in ethanol: Monomer partitioning behavior and locus of polymerization[J]. Journal of Polymer Science Part B:Polymer Physics,1988,26:1187-1203.
[11]Kawaguchi H. Functional polymer microspheres[J]. Progress in Polymer Science,2000, 25:1171-1210.
[12]Barret K E J. Dispersion polymerisation in organic media[J]. British Polymer Journal, 1973,5:259-271.
[13]Shen S, Sudol E D, El-Aasser M S. Control of particle size in dispersion polymerization of methyl methacrylate[J]. Journal of Polymer Science Part A:Polymer Chemistry,1993,31: 1393-1402.
[14]Prochazka O, Stejskal J. Spherical particles obtained by dispersion polymerization:model calculations[J]. Polymer,1992,33:3658-3663.
[15]Paine A J. Dispersion polymerization of styrene in polar solvents.7. A simple mechanistic model to predict particle size[J]. Macromolecules,1990,23:3109-3117.
[16]Y. Y. Lu, Ph.D. dissertation, Lehigh University, Bethlehem, PA,1988.
[17]Shen S, Sudol E D, El-Aasser M S. Dispersion polymerization of methyl methacrylate: Mechanism of particle formation[J]. Journal of Polymer Science Part A:Polymer Chemistry,1994,32:1087-1100.
[18]王占丽,刘莲英,邓建平等.分散聚合制备单分散阳离子型聚苯乙烯微球[J].北京化工大学学报：自然科学版,2007,34(1)：39-43.
[19]赵庆美,曾黎明.中空聚合物微粒制备方法研究进展[J].现代涂料与涂装,2008,11：3-6.
[20]Kowalski et al. US Patents,1984:4427836.
[21]Okubo M, Konishi Y, Minami H[J]. Colloid Polymer Science,1998,276:638-642.
[22]Konishi Y, Okubo M, Minami H[J]. Colloid Polymer Science,2003,281:123-129.
[23]Okubo M, Konishi Y, Inohara T[J]. Journal of Applied Polymer Science,2002,86(5): 1087-1091.
[24]Minami H, Kobayashi H, Okubo M[J]. Langmuir,2005,21:5655-5658.
[25]Kim B S, Kim J W, Suh K D[J]. Applied Polymer Science,2000,76:38-44.
[26]O'Brien D F,Armitage B,Benedicto A, Bennett D E, Lamparski H G, Lee Y S, Srisiri W, Sisson T M. Polymerization of Preformed Self-Organized Assemblies [J]. Accounts of Chemical Research,1998,31:861-868.
[27]刘鹏,田军,刘维民.空心聚合物纳米球研究进展[J].化工进展,2004(1)：15-20.
[28]Decher G, Hong J D. Buildup of ultrathin multilayer films by a selfassembly process.1. consecutive adsorption anionic and cationic bipolar amphiphiles on charged surfaces [J]. Makromol Chem Makromol Symp,1991,46:321-327.
[29]王虹,廖学红.空心微球结构材料的制备与应用[J].纳米材料与结构,2006,10：470-475.
[30]张萍,冯年平,武培怡.聚合物空心纳米球及其在药学领域的应用[J].药学进展,2005,30：350-352.
[31]Caruso F. Chem. Hollow Capsule Processing through Colloidal Templating and Self-Assembly [J]. Chemistry-A European Journal.2000,6 (3):413-419.
[32]Kim S W, Lee W Y, Hyeon T. Fabrication of Hollow Palladium Spheres and Their Successful Application to the Recyclable Heterogeneous Catalyst for Suzuki Coupling Reactions [J]. Journal of the American Chemical Society,2002,124 (26):7642-7643.
[33]Shchukin D G, Radtchenko IL, Sukhorukov G B. Synthesis of Nanosized Magnetic Ferrite Particles Inside Hollow Polyelectrolyte Capsules [J]. Journal of Physical Chemistry B,2003,107 (1):86-90.
[34]Shchukin D G, Radtchenko IL, Sukhorukov GB. Micron-scale hollow polyelectrolyte capsules with nanosized magnetic Fe3O4 inside [J]. Materials Letters,2003,57:1743-1747.
[35]Dahne L, Leporatti S, Donath E, Mohwald H. Fabrication of Micro Reaction Cages with Tailored Properties [J]. Journal of the American Chemical Society,2001,123:5431-5436.
[36]Antipov A, Shchukin D, Fedutik Y, Zanaveskina I, Klechkovskaya V, Sukhorukov D, Mohwald H. Urease-Catalyzed Carbonate Precipitation inside the Restricted Volume of Polyelectrolyte Capsules [J]. Macromolecular Rapid Communications,2003,24:274-277.
[38]S, Nemanick EJ, Lewis NS. Electrochemical polymerization of aniline monomers infiltrated into well-ordered truncated eggshell structures of polyelectrolyte multilayers [J].
Langmuir,2004,20(2):19-26.
[39]Seiner J A, Microvoids as Pigments. A Review [J]. Industrial and Engineering Chemistry Production Research.1978(17):302-317.
[40]Brown T. Relationship Between Hollow Sphere Pigment Geometry and Optical Performance of Finished Paper Coatings [C].TAPPI Proceedings 1991 Coating Conference,1991,pp.113-212.
[41]Han S, Shi X, Zhou F. Polyelectrolyte hollow sphere lithographic patterning of surfaces: construction of 2-dimensional well-ordered metal arrays [J]. Nano Letters,2002,2: 97-100.
[42]Nemanick E J, Lewis N S. Electrochemical polymerization of aniline monomers infiltrated into well-ordered truncated eggshell structures of polyelectrolyte multilayers [J]. Langmuir,2004,20(2):19-26.
[43]Shi X Y, Shen M W, Mohwald H. Polyelectrolyte multilayer nanoreactors toward the synthesis of diverse nanostructured materials [J]. Progress in Polymer Science,2004,29: 987-1019.
[44]Baumeister E, Klaeger S. Advanced New Lightweight Materials:Hollow-Sphere Composites (HSCs) for Mechanical Engineering Applications [J]. Advanced Engineering Materials,2003,5(9):673-677.
[45]Huang J, Xie Y, Li B, Liu Y, Qian Y, Zhang S. In-Situ Source-Template-Interface Reaction Route to Semiconductor CdS Submicrometer Hollow Spheres [J]. Advanced Materials,2000,12:808-811.
[46]Caruso F, Shi X Y, Caruso R A, A SuSha. Hollow Titania Spheres from Layered Precursor Deposition on Sacrificial Colloidal Core Particles [J]. Advanced Materials, 2001,13(10):740-743.
[47]阚成友,洪曼青,孔祥正,林润雄,焦书科.核壳结构聚合物复合粒子的合成与表征[J].化工科技,1999,7(2)：1-4.
[48]Barrett K E J, Thomas H R. Kinetics of dispersion polymerization of soluble monomers. Ⅰ. Methyl methacrylate [J]. Journal of Polymer Science Part A:Polymer Chemistry,1969,7: 2621-2650.
[49]Okubo M, Konishi Y, Inohara T, Minami H. Production of Hollow Polymer Particles by Suspension Polymerizations for Ethylene Glycol Dimethacrylate/Toluene Droplets Dissolving Styrene-Methyl Methacrylate Copolymers[J]. Journal of Applied Polymer Science,2002,86:1087-1091.
[50]Kobayashi H, Miyanaga E, Okubo M. Preparation of Multihollow Polymer Particles by Seeded Emulsion Polymerization Using Seed Particles with Incorporated Nonionic Emulsifier[J]. Langmuir,2007,23:8703-8708.
[51]Shen S, Sudol E D, El-Aasser M S. Control of particle size in dispersion polymerization of methyl methacrylate [J]. Journal of Polymer Science Part A:Polymer Chemistry,1993, 31:1393-1402
[52]Adams M E, Russell G T, Casey B S, Gilbert R G, Napper D H. Bimolecular Termination Events in the Seeded Emulsion Polymerization of Styrene[J]. Macromolecules,1990,23: 4624-4634.