GCSE CIE Chemistry: Polymers Revision Notes | GCSE CIE 化学：聚合物考点精讲

📚 GCSE CIE Chemistry: Polymers Revision Notes | GCSE CIE 化学：聚合物考点精讲

Polymers are giant molecules made up of many repeating units called monomers. In GCSE CIE Chemistry, you are expected to understand how addition and condensation polymers form, their typical properties, the differences between natural and synthetic polymers, and the environmental challenges linked to plastic waste. This comprehensive guide breaks down every key concept into clear, alternating English and Chinese explanations, paired with chemical equations and structural drawings written in Unicode.

聚合物是由许多称为单体的重复单元构成的巨大分子。在 GCSE CIE 化学考试中，你需要理解加聚物和缩聚物是如何形成的、它们的典型性质、天然与合成聚合物的区别，以及与塑料废弃物相关的环境挑战。这份详细指南将每个关键概念分解为清晰的中英对照解释，并配有使用 Unicode 编写的化学方程式与结构图。

1. What Are Polymers? | 什么是聚合物？

A polymer is a long-chain molecule made from many small, simple molecules called monomers. Thousands or even millions of monomer units can join together through covalent bonds to form a macromolecule. The word ‘polymer’ comes from Greek: ‘poly’ meaning many, and ‘meros’ meaning parts.

聚合物是由许多小的简单分子（称为单体）通过共价键连接而成的长链分子。成千上万甚至数以百万计的单体单元可以连接起来形成一个高分子。”聚合物”一词源自希腊语，”poly”意为多，”meros”意为部分。

The repeating unit in a polymer chain has the same atomic composition as the monomer, although the bonding arrangement changes during polymerisation. For addition polymers, the repeating unit has the same formula as the monomer, but for condensation polymers, a small molecule such as water or hydrogen chloride is lost each time a monomer link forms.

聚合物链中的重复单元与单体具有相同的原子组成，尽管在聚合过程中键的排列发生了变化。对于加成聚合物，重复单元与单体的化学式相同；但对于缩合聚合物，每形成一个单体连接就会失去一个小分子，例如水或氯化氢。

Polymers can be classified as natural (e.g. proteins, starch, DNA) or synthetic (e.g. poly(ethene), nylon). Synthetic polymers are often called plastics when they can be moulded into shape.

聚合物可分为天然聚合物（如蛋白质、淀粉、DNA）或合成聚合物（如聚乙烯、尼龙）。合成聚合物在可以被塑造成型时，常被称为塑料。

2. Addition Polymerisation | 加成聚合

Addition polymerisation is the process in which unsaturated monomers (usually alkenes) join together without the loss of any small molecules. Each monomer must contain a carbon–carbon double bond (C=C). Under high pressure and in the presence of a catalyst, the double bond opens up, allowing monomers to link by single covalent bonds to form a saturated long chain.

加成聚合是不饱和单体（通常是烯烃）在不失去任何小分子的情况下连接在一起的过程。每个单体必须含有一个碳碳双键（C=C）。在高压和催化剂作用下，双键打开，使单体通过单共价键连接起来，形成饱和的长链。

The general equation for addition polymerisation of an alkene can be represented as:

烯烃加成聚合的通用方程式可表示为：

n CH₂=CHR → –(CH₂-CHR)–ₙ

Here, R represents any atom or group attached to the double-bonded carbons, such as H (ethene), CH₃ (propene), Cl (chloroethene) or F (tetrafluoroethene). The subscript n indicates a large number of repeating units, often hundreds or thousands.

这里 R 代表连接在双键碳上的任何原子或基团，例如 H（乙烯）、CH₃（丙烯）、Cl（氯乙烯）或 F（四氟乙烯）。下标 n 表示大量的重复单元，通常是几百或几千。

Only monomers with C=C bonds can undergo addition polymerisation. The polymer backbone is a continuous chain of carbon atoms, making addition polymers chemically inert and non-biodegradable under normal conditions.

只有含有 C=C 键的单体才能发生加成聚合。聚合物的主链是一连续的碳原子链，使得加成聚合物在正常条件下化学惰性且不可生物降解。

3. Structure and Properties of Addition Polymers | 加成聚合物的结构与性质

Addition polymers consist of long saturated carbon chains with various side groups. These chains can pack closely together, leading to strong intermolecular forces (van der Waals’ forces or London dispersion forces). As the chain length increases, the melting point and strength of the polymer generally rise.

加成聚合物由带有各种侧基的饱和长碳链组成。这些链可以紧密堆积，产生较强的分子间力（范德华力或伦敦色散力）。随着链长增加，聚合物的熔点和强度通常升高。

Poly(ethene) is flexible and low in strength because it has a simple repeating unit –(CH₂-CH₂)– with only hydrogen atoms as side groups. Introducing larger or more polar side groups increases the stiffness and melting point. For example, poly(chloroethene) (PVC) has bulkier chlorine atoms, making it harder and more rigid than poly(ethene).

聚乙烯柔韧且强度较低，因为它的重复单元 –(CH₂-CH₂)– 简单，只有氢原子作为侧基。引入更大或极性更强的侧基会增加刚性和熔点。例如，聚氯乙烯（PVC）有较大的氯原子，使其比聚乙烯更硬、更具刚性。

Cross-linking between polymer chains can further alter properties: lightly cross-linked polymers are elastic, while highly cross-linked polymers form rigid thermosetting materials. Addition polymers are usually thermoplastic, meaning they soften when heated and can be remoulded – a property explained by the absence of strong covalent bonds between chains.

聚合物链之间的交联可以进一步改变性质：轻微交联的聚合物有弹性，而高度交联的聚合物形成刚性的热固性材料。加成聚合物通常是热塑性的，这意味着它们在加热时软化并能重新塑形——这一性质可以通过链间缺乏强共价键来解释。

4. Common Addition Polymers | 常见加成聚合物

You are expected to recall the monomer, repeating unit, and typical uses of several addition polymers for your CIE IGCSE Chemistry exam.

在 CIE IGCSE 化学考试中，你需要记住几种加成聚合物的单体、重复单元和典型用途。

Polymer	Monomer	Repeating Unit	Uses
Poly(ethene) (PE)	Ethene CH₂=CH₂	–(CH₂–CH₂)–ₙ	Plastic bags, bottles, cling film
Poly(propene) (PP)	Propene CH₂=CHCH₃	–(CH₂–CH(CH₃))–ₙ	Ropes, carpets, crates
Poly(chloroethene) (PVC)	Chloroethene CH₂=CHCl	–(CH₂–CHCl)–ₙ	Window frames, pipes, insulation
Poly(tetrafluoroethene) (PTFE)	Tetrafluoroethene CF₂=CF₂	–(CF₂–CF₂)–ₙ	Non-stick coatings, electrical insulation

Poly(ethene) is produced in two main forms: low-density poly(ethene) (LDPE) and high-density poly(ethene) (HDPE). LDPE is formed at high pressure with a little oxygen initiating the reaction; it has branched chains, making it flexible and useful for film and bags. HDPE uses a catalyst at lower pressure, producing straight chains that pack closely, giving it greater rigidity and strength.

聚乙烯有两种主要形式：低密度聚乙烯（LDPE）和高密度聚乙烯（HDPE）。LDPE 在高压下用少量氧气引发反应生成；它有支链，因此柔韧，适用于薄膜和袋子。HDPE 使用催化剂在较低压力下制备，生成直链，能紧密堆积，从而具有更高的刚性和强度。

5. Condensation Polymerisation | 缩合聚合

Condensation polymerisation involves monomers with two functional groups reacting together, with the elimination of a small molecule (often water or hydrogen chloride) for each new bond formed. Unlike addition polymerisation, the monomers do not need a carbon–carbon double bond.

缩合聚合涉及带有两个官能团的单体相互反应，每形成一个新键时就会失去一个小分子（通常是水或氯化氢）。与加成聚合不同，单体不需要碳碳双键。

The two most important types of condensation polymers studied are polyesters and polyamides. A polyester forms from a diol (a molecule with two –OH groups) and a dicarboxylic acid (a molecule with two –COOH groups), releasing water. A polyamide forms from a diamine (two –NH₂ groups) and a dicarboxylic acid or a diacyl dichloride, also releasing water or hydrogen chloride.

研究的两种最重要的缩合聚合物是聚酯和聚酰胺。聚酯由二醇（含有两个 –OH 基团的分子）和二羧酸（含有两个 –COOH 基团的分子）形成，释放出水。聚酰胺由二胺（两个 –NH₂ 基团）和二羧酸或二酰氯形成，同样释放出水或氯化氢。

Because water is lost, the repeat unit of a condensation polymer has fewer atoms than the sum of the two monomers. You must be able to identify the monomer structures from the repeat unit and vice versa by adding back water (H₂O) across the amide or ester linkage.

由于失去了水，缩聚物的重复单元比两种单体之和少一些原子。你必须能够通过向酰胺键或酯键处加水（H₂O）的方式，从重复单元逆推单体结构，反之亦然。

6. Polyesters and Nylons | 聚酯与尼龙

Polyesters, such as Terylene (PET), are made from ethane-1,2-diol and benzene-1,4-dicarboxylic acid. The ester linkage –COO– repeats along the chain. These polymers are used widely in clothing, plastic bottles, and food packaging.

聚酯，例如涤纶（PET），由乙二醇（1,2-乙二醇）和对苯二甲酸（1,4-苯二甲酸）制成。酯键 –COO– 沿链重复。这些聚合物广泛用于服装、塑料瓶和食品包装。

n HO–CH₂CH₂–OH + n HOOC–C₆H₄–COOH → –[O–CH₂CH₂–OOC–C₆H₄–CO]–ₙ + 2n H₂O

Nylon-6,6, a common polyamide, is formed from hexane-1,6-dioic acid (adipic acid) and 1,6-diaminohexane. The repeating unit contains an amide linkage –CONH–. Nylons are strong, resistant to abrasion, and used for ropes, fabrics, and engineering plastics.

尼龙-6,6 是一种常见的聚酰胺，由己二酸（1,6-己二酸）和 1,6-己二胺形成。重复单元含有酰胺键 –CONH–。尼龙强度高、耐磨，用于绳索、织物和工程塑料。

n H₂N–(CH₂)₆–NH₂ + n HOOC–(CH₂)₄–COOH → –[NH–(CH₂)₆–NHCO–(CH₂)₄–CO]–ₙ + 2n H₂O

In the exam, you may be asked to draw a section of polymer chain showing two repeat units or to identify the monomers from a given short section of a polyester or polyamide. Always remember to show the linking functional group correctly and indicate continuation bonds at the ends of the repeat unit.

在考试中，你可能会被要求画出显示两个重复单元的聚合物链段，或者从给定的聚酯或聚酰胺短链段中识别单体。务必正确表示连接官能团，并在重复单元末端标出延伸键。

7. Natural Polymers and Biopolymers | 天然聚合物与生物聚合物

Nature produces a huge variety of polymers that are essential for life. Proteins are condensation polymers made from amino acids. Each amino acid has an amine group (–NH₂) and a carboxyl group (–COOH). During protein synthesis, amino acids link through peptide bonds (–CONH–) with the loss of water, forming polypeptides. The sequence of amino acids determines the protein’s shape and function.

天然界产生了大量对生命至关重要的聚合物。蛋白质是由氨基酸制成的缩合聚合物。每个氨基酸都有一个胺基（–NH₂）和一个羧基（–COOH）。在蛋白质合成过程中，氨基酸通过肽键（–CONH–）连接并失去水，形成多肽链。氨基酸的序列决定了蛋白质的形状与功能。

Starch and cellulose are natural addition polymers made from glucose monomers. Starch is a mixture of amylose (a largely unbranched polymer of α-glucose) and amylopectin (branched). Cellulose is a straight-chain polymer of β-glucose and provides structural support in plant cell walls. Both are carbohydrates with the general formula (C₆H₁₀O₅)ₙ. Glycogen, found in animals, is similar to amylopectin but more highly branched.

淀粉和纤维素是由葡萄糖单体制成的天然加成聚合物。淀粉是直链淀粉（主要由 α-葡萄糖构成的无支链聚合物）和支链淀粉（有支链）的混合物。纤维素是 β-葡萄糖的直链聚合物，为植物细胞壁提供结构支撑。两者都是碳水化合物，通式为 (C₆H₁₀O₅)ₙ。动物体内的糖原与支链淀粉类似，但支链更多。

DNA (deoxyribonucleic acid) is another biologically crucial condensation polymer. Its monomers are nucleotides, each consisting of a phosphate group, a deoxyribose sugar, and a nitrogenous base. Nucleotides condense to form a sugar–phosphate backbone with the bases as side groups. Two strands wind together into the famous double helix.

DNA（脱氧核糖核酸）是另一种生物学上至关重要的缩合聚合物。其单体是核苷酸，每个核苷酸由一个磷酸基团、一个脱氧核糖和一个含氮碱基组成。核苷酸缩合形成糖-磷酸骨架，碱基作为侧基。两条链缠绕成著名的双螺旋结构。

8. Thermoplastics vs. Thermosets | 热塑性塑料与热固性塑料

Thermoplastics are polymers that soften when heated and harden upon cooling – a process that can be repeated many times. This behaviour arises because the polymer chains are held together by intermolecular forces but not by strong covalent cross-links. Examples include poly(ethene), poly(propene), PVC, and nylon (when not heavily cross-linked).

热塑性塑料是加热时软化、冷却时硬化的聚合物——这个过程可以重复多次。这种行为产生的原因是聚合物链之间仅通过分子间力结合，没有强大的共价交联。例子包括聚乙烯、聚丙烯、PVC 和尼龙（未高度交联时）。

Thermosetting plastics, by contrast, do not soften when heated. They have extensive covalent cross-links between polymer chains, which lock the structure into a rigid network. Once set, thermosets cannot be remoulded and will char or burn on strong heating. Bakelite (used in electrical fittings) and melamine resin (used for kitchen worktops) are common examples.

相比之下，热固性塑料在加热时不会软化。它们在聚合物链之间有大量的共价交联，将结构锁定为刚性网络。一旦固化，热固性塑料就无法重新塑形，在强热下会炭化或燃烧。酚醛树脂（用于电气配件）和三聚氰胺树脂（用于厨房台面）是常见的例子。

Understanding this difference is crucial for selecting materials for specific uses and for explaining why some plastics can be recycled by melting and remoulding while others cannot.

理解这一区别对于选择特定用途的材料，以及解释为何某些塑料可以通过熔化和重塑进行回收而另一些则不能，至关重要。

9. Polymers and the Environment | 聚合物与环境

Most addition polymers are non-biodegradable because they consist of saturated carbon-carbon backbones that microorganisms cannot break down. Discarded plastics therefore persist in the environment for hundreds of years, causing harm to wildlife and accumulating in oceans as microplastics.

大多数加成聚合物是不可生物降解的，因为它们由饱和的碳-碳主链组成，微生物无法将其分解。因此，废弃塑料在环境中会存留数百年，对野生动物造成危害，并以微塑料的形式在海洋中积聚。

Several strategies exist to manage polymer waste: landfilling, incineration with energy recovery, recycling, and development of biodegradable plastics. Landfill is simple but takes up space and can lead to leaching of additives. Incineration reduces volume but releases carbon dioxide and possibly toxic gases unless carefully controlled. Recycling involves melting and re-moulding thermoplastics, but mixed plastic waste is difficult to separate and reprocess.

处理聚合物废弃物有若干策略：填埋、焚烧发电、回收利用以及开发可生物降解塑料。填埋简单但占用空间，并可能导致添加剂渗出。焚烧减小体积但会释放二氧化碳，若控制不当还可能释放有毒气体。回收包括熔化并重塑热塑性塑料，但混合塑料废弃物难以分离和再加工。

Biodegradable polymers, such as some polyesters and plastics derived from plant starch, can be broken down by microorganisms into water, carbon dioxide, and harmless biomass. However, their uptake is limited by cost and performance compared with conventional plastics.

可生物降解聚合物，如某些聚酯和源于植物淀粉的塑料，能被微生物分解成水、二氧化碳和无害的生物质。然而，与传统塑料相比，其推广受限于成本和性能。

The CIE exam may ask you to discuss the environmental impacts of polymers, the pros and cons of recycling versus incineration, or to suggest ways to reduce polymer waste. Always back up your points with chemical reasoning, such as bond strength, saturation, and the conditions needed for combustion.

CIE 考试可能要求你讨论聚合物的环境影响、回收与焚烧的利弊，或提出减少聚合物废弃物的方法。始终用化学推理支持你的观点，如键强、饱和度和燃烧所需的条件。

10. Drawing and Identifying Polymers | 绘制与识别聚合物

A vital practical skill is drawing a section of a polymer chain given its monomer, and deducing the monomer from a polymer structure. For addition polymers, start by showing three or four monomer units linked together, ensuring the correct orientation of the side groups along the carbon backbone. Use extension bonds (wavy lines or – symbols) at both ends to indicate the chain continues.

一个重要的实践技能是根据单体画出聚合物链的一段，以及从聚合物结构推导单体。对于加成聚合物，先画出三到四个单体单元连接在一起，确保侧基沿着碳骨架的正确方向。在两端使用延伸键（波浪线或 – 符号）表示链条继续延伸。

For condensation polymers, identify the linking group (ester –COO– or amide –CONH–) and mentally add water back to reconstruct the monomers. For a polyester, breaking the C–O bond of the ester group and adding H to oxygen and OH to the carbonyl carbon gives back a diol and a dicarboxylic acid respectively.

对于缩聚物，识别连接基团（酯基 –COO– 或酰胺基 –CONH–），并在脑海中加水以重构单体。对于聚酯，断开酯基的 C–O 键，将 H 加到氧原子上、OH 加到羰基碳上，即可分别得到二醇和二羧酸。

Practice drawing repeating units for PTFE, PVC, Terylene, and Nylon-6,6. Always write the repeat unit in square brackets with subscript n to show it repeats many times. In CIE exams, you may be asked to ‘draw the structure of the polymer formed from monomer X’ or ‘identify the monomer(s) from the repeat unit shown’. Being able to manipulate these structures confidently is worth several marks.

练习绘制 PTFE、PVC、涤纶和尼龙-6,6 的重复单元。始终将重复单元写在方括号内，并带有下标 n，以表明其重复多次。在 CIE 考试中，你可能被要求”画出由单体 X 形成的聚合物的结构”或”从显示的重复单元中识别单体”。能够熟练处理这些结构是值得几分的。

11. Summary of Key Comparisons | 关键对比总结

Feature	Addition Polymerisation	Condensation Polymerisation
Monomer requirement	C=C double bond	Two functional groups per monomer (or two types of monomers with one functional group each)
Small molecule lost	None	Usually H₂O or HCl
Chain composition	Carbon backbone only	Backbone contains heteroatoms (O, N)
Biodegradability	Generally non-biodegradable	Polyesters and polyamides can be biodegradable
Examples	PE, PP, PVC, PTFE	PET (polyester), Nylon-6,6 (polyamide)

This comparison emphasises the fundamental chemical differences that determine the properties and environmental fate of each polymer class. Remembering these contrasts will help you answer essay-style questions confidently and quickly.

这个对比强调了决定每类聚合物性质和环境命运的根本化学差异。记住这些对比将帮助你自信而迅速地回答论述式问题。

Polymers are a cornerstone of both modern materials science and biological systems. By mastering the definitions, reaction types, structural drawing, and environmental implications covered here, you will be fully equipped for the GCSE CIE Chemistry examination on polymers. Revise by practising drawing repeat units, writing polymerisation equations, and explaining how structure relates to properties and disposal.

聚合物是现代材料科学和生物体系的基石。通过掌握本文涵盖的定义、反应类型、结构绘制和环境影响，你将全面准备好 GCSE CIE 化学考试中关于聚合物的内容。复习时，请练习绘制重复单元、书写聚合方程式，并解释结构如何与性质和废弃处理相关。

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GCSE CIE Chemistry: Polymers Revision Notes | GCSE CIE 化学：聚合物 考点精讲