📚 Addition Polymerisation and Polymers | 加成聚合反应与聚合物
Addition polymerisation is a reaction in which many small alkene monomer molecules join together to form one giant polymer molecule. In this process, the carbon–carbon double bond of each monomer opens up, allowing the monomers to link into long chains without the loss of any small molecule.
加成聚合反应是指许多小分子烯烃单体相互连接形成一条巨大聚合物分子的反应。在此过程中，每个单体的碳碳双键打开，使单体连接成长链，且不会有任何小分子副产物生成。
1. What Is Addition Polymerisation? | 什么是加成聚合反应？
Addition polymerisation is a process in which unsaturated alkene monomers, each containing at least one C=C double bond, add together to form a long-chain polymer. Because the monomers are all alkenes, the polymerisation requires no other reactants, and no waste products such as water or hydrogen chloride are formed. The polymer contains exactly the same atoms as the combined monomers.
加成聚合反应是含有碳碳双键的不饱和烯烃单体相互加成形成长链聚合物的过程。由于所有单体均为烯烃，因此聚合反应不需要其他反应物，也不会产生水或氯化氢等副产物。聚合物所含的原子总数恰好等于所有单体的原子总数之和。
For example, ethene (C₂H₄) can polymerise to form poly(ethene), commonly known as polythene. The equation can be written as:
例如，乙烯（C₂H₄）可以聚合生成聚（乙烯），俗称聚乙烯。反应方程式可写为：
n CH₂=CH₂ → [–CH₂–CH₂–]ₙ
The symbol n represents a very large number of repeating units, typically thousands or even millions. A single polymer molecule is called a macromolecule, and the process of forming it is a type of chain-growth polymerisation.
符号n代表非常大的重复单元数目，通常为数千甚至数百万。单个聚合物分子称为大分子，这一形成过程属于链增长聚合。
2. Which Monomers Can Undergo Addition Polymerisation? | 哪些单体可发生加成聚合反应？
Only monomers containing at least one carbon–carbon double bond (C=C) can undergo addition polymerisation. In A-Level chemistry, the most common monomers are alkenes and substituted alkenes — compounds in which one or more hydrogen atoms on the alkene have been replaced by a different atom or group, such as chlorine (–Cl), a methyl group (–CH₃), or a nitrile group (–C≡N).
只有含有至少一个碳碳双键（C=C）的单体才能发生加成聚合反应。在A-Level化学中，最常见的单体是烯烃和取代烯烃——即烯烃上的一个或多个氢原子被其他原子或基团（如氯原子–Cl、甲基–CH₃或氰基–C≡N）取代的化合物。
Common examples of monomers include:
常见的单体包括：
- Ethene CH₂=CH₂ → poly(ethene), used in plastic bags and bottles
- 乙烯 CH₂=CH₂ → 聚（乙烯），用于塑料袋和瓶子
- Propene CH₃–CH=CH₂ → poly(propene), used in ropes and crates
- 丙烯 CH₃–CH=CH₂ → 聚（丙烯），用于绳索和货箱
- Chloroethene (vinyl chloride) CH₂=CHCl → poly(chloroethene) / PVC, used in pipes and window frames
- 氯乙烯 CH₂=CHCl → 聚（氯乙烯）/ PVC，用于管道和窗框
- Tetrafluoroethene CF₂=CF₂ → poly(tetrafluoroethene) / PTFE (Teflon), used as a non-stick coating
- 四氟乙烯 CF₂=CF₂ → 聚（四氟乙烯）/ PTFE（特氟龙），用作不粘涂层
3. The Free-Radical Mechanism of Addition Polymerisation |
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