Contents xi 6.6 Step Copolymerization.....·..··················· 127 6.7 Techniques of Step Polymerization.................... 129 6.8 Synthesis of Dendritic Polymers.·.·.·············· 130 6.8.1 Divergent Method...··.·..·..······ 130 6.8.2 Convergent System........................ 131 6.8.3 Molecular Weight of Dendrimer..··..·········· 133 6.9 Hyperbranched Copolymer......................... 133 6.10 Problems...........··.. 134 References.········ 135 7 Radical Chain Polymerization........,..·.·......··...·. 137 7.1 Effect of Chemical Structure of Monomer on the Structural Arrangement of Polymer......·····.···. 138 7.2 Initiators of Radical Chain Polymerization..·.....······· 142 7.2.1 Thermal Initiators.......................... 142 7.2.2 Decomposition Temperature and Half-Life of Thermal Initiators.,......·,..,.·.···..· 144 7.2.3 Initiation Promoters,.,,...··············· 147 7.2.4 Redox Initiators...················ 147 7.2.5 Photoinitiators....。.·· 148 7.2.6 Electrochemical Initiation....... 149 7.3 Techniques of Free Radical Chain Polymerization 150 7.3.1 Bulk Polymerization..·.....·.....········· 150 7.3.2 Suspension Polymerization·..·,....·.......·· 150 7.3.3 Solution Polymerization............ 151 7.3.4 Emulsion Polymerization,...················· 151 7.4 Reaction Mechanism of Free Radical Chain Polymerization..............。.····· 153 7.5 Kinetics of Free Radical Chain Polymerization....······· 155 7.5.1 Rate of Polymerization...................... 156 7.5.2 Average Kinetic Chain Length下，..........·.. 157 7.5.3 Chain Transfer Reactions .......... 158 7.6 Living Polymerization..............·...··..······ 162 7.6.1 Living Radical Polymerization...... 444 162 7.6.2 Atom Transfer Radical Polymerization... 163 7.6.3 Nitroxide-Mediated Polymerization.............. 164 7.6.4 Radical Addition-Fragmentation Transfer ........ 164 7.7 Polymerization of Dienes........................... 165 7.8 Temperature Effect of the Free Radical Polymerization...···. 168 7.8.1 Activation Energy and Frequency Factor.......... 169 7.8.2 Rate of Polymerization.......,.....·.,·.···. 170 7.8.3 Degree of Polymerization················ 171
6.6 Step Copolymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 6.7 Techniques of Step Polymerization. . . . . . . . . . . . . . . . . . . . 129 6.8 Synthesis of Dendritic Polymers. . . . . . . . . . . . . . . . . . . . . . 130 6.8.1 Divergent Method. . . . . . . . . . . . . . . . . . . . . . . . . . 130 6.8.2 Convergent System . . . . . . . . . . . . . . . . . . . . . . . . . 131 6.8.3 Molecular Weight of Dendrimer. . . . . . . . . . . . . . . . 133 6.9 Hyperbranched Copolymer . . . . . . . . . . . . . . . . . . . . . . . . . 133 6.10 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 7 Radical Chain Polymerization. . . . . . . . . . . . . . . . . . . . . . . . . . . 137 7.1 Effect of Chemical Structure of Monomer on the Structural Arrangement of Polymer. . . . . . . . . . . . . . . 138 7.2 Initiators of Radical Chain Polymerization. . . . . . . . . . . . . . . 142 7.2.1 Thermal Initiators . . . . . . . . . . . . . . . . . . . . . . . . . . 142 7.2.2 Decomposition Temperature and Half-Life of Thermal Initiators . . . . . . . . . . . . . . . . . . . . . . . . 144 7.2.3 Initiation Promoters . . . . . . . . . . . . . . . . . . . . . . . . 147 7.2.4 Redox Initiators . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 7.2.5 Photoinitiators . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 7.2.6 Electrochemical Initiation . . . . . . . . . . . . . . . . . . . . 149 7.3 Techniques of Free Radical Chain Polymerization . . . . . . . . . 150 7.3.1 Bulk Polymerization . . . . . . . . . . . . . . . . . . . . . . . . 150 7.3.2 Suspension Polymerization . . . . . . . . . . . . . . . . . . . 150 7.3.3 Solution Polymerization . . . . . . . . . . . . . . . . . . . . . 151 7.3.4 Emulsion Polymerization. . . . . . . . . . . . . . . . . . . . . 151 7.4 Reaction Mechanism of Free Radical Chain Polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 7.5 Kinetics of Free Radical Chain Polymerization . . . . . . . . . . . 155 7.5.1 Rate of Polymerization . . . . . . . . . . . . . . . . . . . . . . 156 7.5.2 Average Kinetic Chain Length m . . . . . . . . . . . . . . . 157 7.5.3 Chain Transfer Reactions . . . . . . . . . . . . . . . . . . . . 158 7.6 Living Polymerization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 7.6.1 Living Radical Polymerization . . . . . . . . . . . . . . . . . 162 7.6.2 Atom Transfer Radical Polymerization . . . . . . . . . . . 163 7.6.3 Nitroxide-Mediated Polymerization. . . . . . . . . . . . . . 164 7.6.4 Radical Addition-Fragmentation Transfer . . . . . . . . . 164 7.7 Polymerization of Dienes. . . . . . . . . . . . . . . . . . . . . . . . . . . 165 7.8 Temperature Effect of the Free Radical Polymerization. . . . . . 168 7.8.1 Activation Energy and Frequency Factor. . . . . . . . . . 169 7.8.2 Rate of Polymerization . . . . . . . . . . . . . . . . . . . . . . 170 7.8.3 Degree of Polymerization . . . . . . . . . . . . . . . . . . . . 171 Contents xi
妨 Contents 7.9 Thermodynamics of Free Radical Polymerization.......... 172 7.9.1 Monomer Reactivity.....,.................. 173 7.9.2 Ceiling Temperature.··················· 175 7.9.3 Characteristics of AS Values of Free Radical Polymerization.......······ 176 7.l0 Molecular Weight Distribution at Low Conversion.···.···· 176 7.11 Synthesis of Commercial Polymers.................... 178 7.ll.1 Polyethylene......·.················· 178 7.l12 Polystyrene....·.······· 179 7.ll.3 Polyvinyl Chloride.........·.···· 180 7.ll.4 Polyvinyl Acetate......··..·.··..·.······· 180 7.11.5 Polyvinylidene Chloride .................... 180 7.11.6 Acryl Polymer.·.,···.·…············ 180 7.l1.7 Fluoropolymers....·················· 181 7.11.8 Cost of Common Polymers.........·.....···. 182 712 Problems.··················· 182 References......。t。。···+· 183 8 Ionic Chain Polymerization..·.....····················· 185 8.1 Characteristics of Ionic Chain Polymerization............ 187 8.2 Cationic Polymerization....·............·.······· 189 8.2.1 Initiators of Cationic Polymerization............. 189 8.2.2 Reaction Mechanisms of Cationic Polymerization .. 190 8.2.3 Kinetics of Cationic Polymerization............. 196 8.2.4 Commercial Cationic Polymerization............ 200 8.3 Anionic Polymerization.··.························ 201 8.3.1 Reaction Mechanisms of Anionic Polymerization.... 201 8.3.2 Kinetics of Anionic Polymerization with Termination..············ 204 8.4 Group Transfer Polymerization....................... 209 8.5 Chain Polymerization of Carbonyl Monomer............. 213 8.5.1 Anionic Polymerization of Carbonyl Monomer 213 8.5.2 Cationic Polymerization of Carbonyl Monomer..... 215 8.5.3 Radical Polymerization of Carbonyl Monomer...... 215 8.5.4 End-Capping Polymerization.................. 216 86 Problems..….·。,···…······…··…···· 217 References...,,·.。········· 218 9 Coordination Polymerization.,·..·.····················· 219 g.1 Heterogeneous Ziegler--Natta Polymerization......·..···. 219 9.l.1 Catalysts........········· 219 9.l.2 Reaction Mechanisms...··.················· 222 9.2 Homogeneous Ziegler-Natta Polymerization............. 225 9.3 Ziegler--Natta Copolymerization.···.················· 229
7.9 Thermodynamics of Free Radical Polymerization . . . . . . . . . . 172 7.9.1 Monomer Reactivity . . . . . . . . . . . . . . . . . . . . . . . . 173 7.9.2 Ceiling Temperature . . . . . . . . . . . . . . . . . . . . . . . . 175 7.9.3 Characteristics of DS Values of Free Radical Polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 7.10 Molecular Weight Distribution at Low Conversion . . . . . . . . . 176 7.11 Synthesis of Commercial Polymers. . . . . . . . . . . . . . . . . . . . 178 7.11.1 Polyethylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 7.11.2 Polystyrene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 7.11.3 Polyvinyl Chloride . . . . . . . . . . . . . . . . . . . . . . . . . 180 7.11.4 Polyvinyl Acetate . . . . . . . . . . . . . . . . . . . . . . . . . . 180 7.11.5 Polyvinylidene Chloride . . . . . . . . . . . . . . . . . . . . . 180 7.11.6 Acryl Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 7.11.7 Fluoropolymers . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 7.11.8 Cost of Common Polymers . . . . . . . . . . . . . . . . . . . 182 7.12 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 8 Ionic Chain Polymerization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 8.1 Characteristics of Ionic Chain Polymerization . . . . . . . . . . . . 187 8.2 Cationic Polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 8.2.1 Initiators of Cationic Polymerization. . . . . . . . . . . . . 189 8.2.2 Reaction Mechanisms of Cationic Polymerization . . . 190 8.2.3 Kinetics of Cationic Polymerization . . . . . . . . . . . . . 196 8.2.4 Commercial Cationic Polymerization . . . . . . . . . . . . 200 8.3 Anionic Polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 8.3.1 Reaction Mechanisms of Anionic Polymerization . . . . 201 8.3.2 Kinetics of Anionic Polymerization with Termination . . . . . . . . . . . . . . . . . . . . . . . . . . 204 8.4 Group Transfer Polymerization. . . . . . . . . . . . . . . . . . . . . . . 209 8.5 Chain Polymerization of Carbonyl Monomer . . . . . . . . . . . . . 213 8.5.1 Anionic Polymerization of Carbonyl Monomer . . . . . 213 8.5.2 Cationic Polymerization of Carbonyl Monomer . . . . . 215 8.5.3 Radical Polymerization of Carbonyl Monomer. . . . . . 215 8.5.4 End-Capping Polymerization . . . . . . . . . . . . . . . . . . 216 8.6 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 9 Coordination Polymerization. . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 9.1 Heterogeneous Ziegler–Natta Polymerization . . . . . . . . . . . . . 219 9.1.1 Catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 9.1.2 Reaction Mechanisms . . . . . . . . . . . . . . . . . . . . . . . 222 9.2 Homogeneous Ziegler–Natta Polymerization . . . . . . . . . . . . . 225 9.3 Ziegler–Natta Copolymerization . . . . . . . . . . . . . . . . . . . . . . 229 xii Contents
Contents xiii 9.4 Metathesis Polymerization.....····················· 230 9.5 Problems......,。...:..。.。。·…·· 231 References·· 232 10 Chain Copolymerization..................·..··..····· 233 10.1 Reaction Kinetics of Free Radical Copolymerization 234 10.1.1 Types of Copolymerization Behavior............ 237 10.1.2 Effect of Reaction Conditions on Radical Copolymerization..·············· 241 10.1.3 Reactivity and Composition of Free Radical Copolymerization 243 10.1.4 Rate of Polymerization of Free Radical Copolymerization...···.·.·············· 253 l0.2 Cationic Copolymerization.......·...,·.·.·········· 256 10.3 Anionic Copolymerization.......................... 259 10.4 Copolymerization Involving Dienes..················· 260 10.5 Block Copolymers...··...·。···················· 261 10.6 Commercial Copolymers....···...················ 263 10.7 Problems.·· 263 References.....。·。 265 l1Ring-0 pening Polymerization....·.·............·.·.·.· 267 11.1 Reactivity of Cyclic Monomers .... 267 11.2 General Aspects of Mechanisms and Kinetics............ 270 113 Cyclic Ethers................................... 271 ll.3.1 Anionic Polymerization of Epoxides..·.·.······ 272 11.3.2 Cationic Polymerization of Epoxides 277 11.3.3 Polymerization of Cyclic Acetals............... 282 ll.3.4 Kinetic Characteristics·..············· 283 11.3.5 Thermodynamic Characteristics................ 285 11.3.6 Commercial Applications of Polymers of Cyclic Ether...·········… 287 288 11.4.1 Cationic Polymerization 444444.44.44444。 288 11.4.2 Hydrolytic Polymerization.................... 290 1l.4.3 Anionic Polymerization.......·....·········· 291 11.4.4 Reactivity of Lactam.........:....·..······ 294 115 Cyclosiloxanes....。...。.。.··········· 294 11.6 Copolymerization.···················· 296 11.7 Problems.........·. 44.444.44.444.4+ 298 References ......... 299 Index.。,。 301
9.4 Metathesis Polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . 230 9.5 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 10 Chain Copolymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 10.1 Reaction Kinetics of Free Radical Copolymerization . . . . . . . 234 10.1.1 Types of Copolymerization Behavior . . . . . . . . . . . . 237 10.1.2 Effect of Reaction Conditions on Radical Copolymerization . . . . . . . . . . . . . . . . . . . . . . . . . . 241 10.1.3 Reactivity and Composition of Free Radical Copolymerization . . . . . . . . . . . . . . 243 10.1.4 Rate of Polymerization of Free Radical Copolymerization . . . . . . . . . . . . . . . . . . . . . . . . . . 253 10.2 Cationic Copolymerization. . . . . . . . . . . . . . . . . . . . . . . . . . 256 10.3 Anionic Copolymerization . . . . . . . . . . . . . . . . . . . . . . . . . . 259 10.4 Copolymerization Involving Dienes . . . . . . . . . . . . . . . . . . . 260 10.5 Block Copolymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 10.6 Commercial Copolymers . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 10.7 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 11 Ring-Opening Polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 11.1 Reactivity of Cyclic Monomers . . . . . . . . . . . . . . . . . . . . . . 267 11.2 General Aspects of Mechanisms and Kinetics . . . . . . . . . . . . 270 11.3 Cyclic Ethers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 11.3.1 Anionic Polymerization of Epoxides . . . . . . . . . . . . . 272 11.3.2 Cationic Polymerization of Epoxides . . . . . . . . . . . . 277 11.3.3 Polymerization of Cyclic Acetals . . . . . . . . . . . . . . . 282 11.3.4 Kinetic Characteristics . . . . . . . . . . . . . . . . . . . . . . 283 11.3.5 Thermodynamic Characteristics . . . . . . . . . . . . . . . . 285 11.3.6 Commercial Applications of Polymers of Cyclic Ether. . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 11.4 Lactams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288 11.4.1 Cationic Polymerization . . . . . . . . . . . . . . . . . . . . . 288 11.4.2 Hydrolytic Polymerization . . . . . . . . . . . . . . . . . . . . 290 11.4.3 Anionic Polymerization . . . . . . . . . . . . . . . . . . . . . . 291 11.4.4 Reactivity of Lactam. . . . . . . . . . . . . . . . . . . . . . . . 294 11.5 Cyclosiloxanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 11.6 Copolymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 11.7 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 Contents xiii
Chapter 1 Introduction Synthetic polymers [1]are vital materials used in modern daily life from pack- aging,electronics,medical devices,clothing,vehicles,buildings,etc.,due to their ease of processing and light weight.The first synthetic polymer,a phenol-form- aldehyde resin,was invented in the early 1900s by Leo Baekeland [2].It was a commercial success invention although most of scientists had no clear concept of polymer structure at that time.Wallace Carothers invented very important poly- mers of neoprene rubber and Nylon in 1930s which shaped the leadership of DuPont in polymer industry.Hermann Staudinger developed theoretical expla- nations of remarkable properties of polymers by ordinary intermolecular forces between molecules of very high molecular weight.He was awarded the Nobel Prize in Chemistry in 1953 for this outstanding contribution.World War II led to significant advances in polymer chemistry with the development of synthetic rubber as natural rubber was not accessible to the Allies.Karl Ziegler and Giulio Natta won the Nobel Prize in Chemistry in 1963,jointly for the development of coordination polymerization to have controlled stereochemistry of polymers using coordination catalysts.Their work has revolutionized the polymer industry to synthesize stereoregular polymers that have mechanical properties superior than that of non-stereoregular polymers.Equally significant work was done by Paul Flory 1974,Nobel laureate on the quantitative investigations of polymer behaviors in solution or in bulk. Most of polymers are insulators,so they have passive functions and used as a bulk material for structure or as thin layer for coating barrier.In 1977,Alan Heeger,Alan MacDiarmid,and Hideki Shirakawa reported high conductivity in iodine-doped polyacetylene.This research earned them the 2000 Nobel Prize in Chemistry.Since then,the application of polymer has expanded into active functional area such as light emitting diode,sensor,solar cell,etc.Polymers can be tailor made to meet the requirements of specific application through molecular design and synthesis.Therefore,they have become the material of choice to face the ever fast changing world from electronics to medical applications. The physical properties of polymers are mainly determined by their chemical structures.Chemical structures of polymers affect their flow and morphology that results in different physical properties.The processability of polymers is controlled W.-F.Su,Principles of Polymer Design and Synthesis, 1 Lecture Notes in Chemistry 82,DOI:10.1007/978-3-642-38730-2_1, Springer-Verlag Berlin Heidelberg 2013
Chapter 1 Introduction Synthetic polymers [1] are vital materials used in modern daily life from packaging, electronics, medical devices, clothing, vehicles, buildings, etc., due to their ease of processing and light weight. The first synthetic polymer, a phenol-formaldehyde resin, was invented in the early 1900s by Leo Baekeland [2]. It was a commercial success invention although most of scientists had no clear concept of polymer structure at that time. Wallace Carothers invented very important polymers of neoprene rubber and Nylon in 1930s which shaped the leadership of DuPont in polymer industry. Hermann Staudinger developed theoretical explanations of remarkable properties of polymers by ordinary intermolecular forces between molecules of very high molecular weight. He was awarded the Nobel Prize in Chemistry in 1953 for this outstanding contribution. World War II led to significant advances in polymer chemistry with the development of synthetic rubber as natural rubber was not accessible to the Allies. Karl Ziegler and Giulio Natta won the Nobel Prize in Chemistry in 1963, jointly for the development of coordination polymerization to have controlled stereochemistry of polymers using coordination catalysts. Their work has revolutionized the polymer industry to synthesize stereoregular polymers that have mechanical properties superior than that of non-stereoregular polymers. Equally significant work was done by Paul Flory 1974, Nobel laureate on the quantitative investigations of polymer behaviors in solution or in bulk. Most of polymers are insulators, so they have passive functions and used as a bulk material for structure or as thin layer for coating barrier. In 1977, Alan Heeger, Alan MacDiarmid, and Hideki Shirakawa reported high conductivity in iodine-doped polyacetylene. This research earned them the 2000 Nobel Prize in Chemistry. Since then, the application of polymer has expanded into active functional area such as light emitting diode, sensor, solar cell, etc. Polymers can be tailor made to meet the requirements of specific application through molecular design and synthesis. Therefore, they have become the material of choice to face the ever fast changing world from electronics to medical applications. The physical properties of polymers are mainly determined by their chemical structures. Chemical structures of polymers affect their flow and morphology that results in different physical properties. The processability of polymers is controlled W.-F. Su, Principles of Polymer Design and Synthesis, Lecture Notes in Chemistry 82, DOI: 10.1007/978-3-642-38730-2_1, Springer-Verlag Berlin Heidelberg 2013 1
2 I Introduction Fig.1.1 Chemical structures (a)Monomer (b)Polymer of(a)monomers and(b)their corresponding polymers H2C=CH2 十CHaCHz H2C=CHCI H2C—CH2 -CHzCHz0jn HOCH2CH2OH -CH2CH2O f-O斗 by their flow characteristics in neat form or in solution which affects by their molecular weight. Polymers are built up by linking together of large number of "monomers." Monomers are small molecules with functional groups (organic compounds)and they can react with each other to form a large molecule.Figure 1.1 shows some commonly used polymers with their chemical structures of monomers and their corresponding polymers.The polymers have to have molecular weight larger than 10,000 to exhibit good mechanical properties for structural use.Oligomer is a molecule that has molecular weight between 1,000 and 10,000.The oligomer has been widely used in coating applications.End group is the chemical structure at the end of the polymer chains.When the polymer is ended with a functional group, such as CH3CH2-[CH2CH2]-CH=CH2,the polymer is called telechelic polymer. In the same way,reactive oligomer is oligomer that contains end groups and capable to undergo polymerization. The size of polymer is determined by the degree of polymerization(DP).It is a total number of structural units,including end groups,and is related to both chain length and molecular weight.For example,the molecular weight of polymethac- rylate with DP =500 is 500 multiplying by 74 (weight of unit)=37,000. Because polymer chains within a given polymer sample are always of varying lengths,we need to use average value,such as number-average molecular weight (M),weight-average molecular weight(Mw),etc.The molecular weight distri- bution (PDD)is defined as dividing Mw over Mn
by their flow characteristics in neat form or in solution which affects by their molecular weight. Polymers are built up by linking together of large number of ‘‘monomers.’’ Monomers are small molecules with functional groups (organic compounds) and they can react with each other to form a large molecule. Figure 1.1 shows some commonly used polymers with their chemical structures of monomers and their corresponding polymers. The polymers have to have molecular weight larger than 10,000 to exhibit good mechanical properties for structural use. Oligomer is a molecule that has molecular weight between 1,000 and 10,000. The oligomer has been widely used in coating applications. End group is the chemical structure at the end of the polymer chains. When the polymer is ended with a functional group, such as CH3CH2–[CH2CH2]n–CH=CH2, the polymer is called telechelic polymer. In the same way, reactive oligomer is oligomer that contains end groups and capable to undergo polymerization. The size of polymer is determined by the degree of polymerization (DP). It is a total number of structural units, including end groups, and is related to both chain length and molecular weight. For example, the molecular weight of polymethacrylate with DP = 500 is 500 multiplying by 74 (weight of unit) = 37,000. Because polymer chains within a given polymer sample are always of varying lengths, we need to use average value, such as number-average molecular weight Mð Þn , weight-average molecular weight Mð Þ w , etc. The molecular weight distribution (PDI) is defined as dividing M w over M n. Fig. 1.1 Chemical structures of (a) monomers and (b) their corresponding polymers 2 1 Introduction