GCSE OCR Chemistry: Polymers – Exam-Focused Revision | GCSE OCR 化学：聚合物考点精讲

📚 GCSE OCR Chemistry: Polymers – Exam-Focused Revision | GCSE OCR 化学：聚合物考点精讲

Polymers are a core topic in GCSE OCR Chemistry, linking organic chemistry with real-world materials. This revision guide covers addition and condensation polymerisation, natural polymers, plastic properties, environmental impact, and key exam techniques – all paired with clear bilingual explanations to strengthen your understanding.

聚合物是 GCSE OCR 化学的核心主题，连接着有机化学与现实材料。这份复习指南涵盖加成聚合与缩合聚合、天然聚合物、塑料性质、环境影响以及关键考试技巧——全部配有清晰的双语解释，帮助你加深理解。

1. Introduction to Polymers | 聚合物简介

A polymer is a large molecule made from many small repeating units called monomers joined together by covalent bonds. The process of forming a polymer from its monomers is called polymerisation.

聚合物是由许多称为单体的小重复单元通过共价键连接而成的大分子。由单体制备聚合物的过程称为聚合反应。

Polymers can be natural, such as DNA and proteins, or synthetic, like poly(ethene) and nylon. OCR questions often expect you to identify the type of polymerisation and the monomer from a given polymer structure.

聚合物可以是天然的，如 DNA 和蛋白质，也可以是合成的，如聚（乙烯）和尼龙。OCR 试题常要求你根据给出的聚合物结构识别聚合类型与单体。

2. Addition Polymerisation | 加成聚合反应

Addition polymerisation occurs when alkene monomers join together without the loss of any small molecules. The carbon–carbon double bond (C=C) breaks open, and monomers add to each other to form a long saturated carbon chain.

加成聚合发生时，烯烃单体相互连接而不失去任何小分子。碳碳双键（C=C）断开，单体彼此加成形成一条长的饱和碳链。

The general equation for addition polymerisation of ethene is:

乙烯加成聚合的总方程式为：

n CH₂=CH₂ → (–CH₂–CH₂–)ₙ

The repeating unit is –CH₂–CH₂– , and ‘n’ represents a large number of repeating units. The polymer name is poly(ethene) or polythene.

重复单元为 –CH₂–CH₂– ，‘n’ 代表大量的重复单元。聚合物名称为聚（乙烯）或聚乙烯。

Always draw the repeating unit with the correct number of bonds and show the extended bonds going through the brackets.

绘制重复单元时务必画出正确的化学键，并让延续键穿出括号。
If the alkene is propene (CH₃–CH=CH₂), the polymer is poly(propene) with repeating unit –CH(CH₃)–CH₂–.

如果烯烃是丙烯（CH₃–CH=CH₂），则聚合物为聚（丙烯），重复单元为 –CH(CH₃)–CH₂–。

3. Drawing Addition Polymers | 绘制加成聚合物

In exam questions, you may be asked to draw the polymer from a given alkene monomer or identify the monomer from a polymer section. Always show the carbon backbone correctly, with side groups in place.

在考试题目中，你可能需要根据给定的烯烃单体绘制聚合物，或从聚合物片段识别单体。务必正确画出碳骨架，并将侧基放在合适位置。

For example, poly(chloroethene) (PVC) has the repeating unit –CH₂–CHCl– and is made from chloroethene (CH₂=CHCl). The monomer must contain the C=C double bond; when drawing the polymer, remove the double bond and extend single bonds on either side.

例如，聚（氯乙烯）（PVC）的重复单元为 –CH₂–CHCl– ，由氯乙烯（CH₂=CHCl）制成。单体必须含有 C=C 双键；绘制聚合物时去掉双键，并在两侧延伸单键。

Common addition polymers to know: poly(ethene), poly(propene), poly(chloroethene) (PVC), and poly(tetrafluoroethene) (PTFE).

需要掌握的常见加成聚合物：聚（乙烯）、聚（丙烯）、聚（氯乙烯）（PVC）和聚（四氟乙烯）（PTFE）。

4. Condensation Polymerisation | 缩合聚合反应

Condensation polymerisation involves monomers joining together with the elimination of a small molecule, usually water or hydrogen chloride. The monomers must each have two functional groups.

缩合聚合涉及单体相互连接并脱去一个小分子，通常是水或氯化氢。每个单体必须具有两个官能团。

Two main families of condensation polymers are polyesters (made from dicarboxylic acids and diols) and polyamides (made from diamines and dicarboxylic acids or amino acids). The functional groups react to form ester linkages (–O–CO–) or amide linkages (–NH–CO–).

缩合聚合物的两个主要家族是聚酯（由二羧酸与二醇制成）和聚酰胺（由二胺与二羧酸或氨基酸制成）。官能团反应形成酯键（–O–CO–）或酰胺键（–NH–CO–）。

Condensation polymers are often stronger and more rigid than addition polymers, and many are used as fibres and engineering plastics.

缩合聚合物通常比加成聚合物更强韧、刚性更好，许多被用作纤维和工程塑料。

5. Polyesters | 聚酯

A polyester is formed when a diol (a molecule with two –OH groups) reacts with a dicarboxylic acid (two –COOH groups). Ester linkages are created, and water is eliminated for each ester bond formed.

当二醇（具有两个 –OH 基团的分子）与二羧酸（两个 –COOH 基团）反应时，生成聚酯。每形成一个酯键都会产生酯键并脱去水。

A typical equation for polyester formation is:

典型的聚酯生成方程式为：

n HO–R–OH + n HOOC–R’–COOH → (–O–R–O–CO–R’–CO–)ₙ + 2n H₂O

R and R’ represent hydrocarbon chains. The structural unit contains the ester group –COO–, which can also be written as –O–CO– when embedded in the chain.

R 和 R’ 代表烃链。结构单元中含有酯基 –COO–，嵌入主链时也可写作 –O–CO–。

Polyethylene terephthalate (PET) is a common polyester used for drinks bottles and clothing fibres. It is made from ethane-1,2-diol and terephthalic acid.

聚对苯二甲酸乙二醇酯（PET）是一种常见的聚酯，用于饮料瓶和服装纤维。它由乙二醇和对苯二甲酸制成。

6. Polyamides and Nylon | 聚酰胺与尼龙

Polyamides are condensation polymers containing the amide linkage –NH–CO–. They can be formed from a diamine and a dicarboxylic acid, eliminating water, or from amino acids which contain both amine and carboxyl groups in the same molecule.

聚酰胺是含有酰胺键 –NH–CO– 的缩合聚合物。它们可由二胺与二羧酸脱去水形成，也可由同一分子中同时含有氨基与羧基的氨基酸形成。

Nylon-6,6 is synthesised from hexane-1,6-diamine and hexane-1,6-dioic acid. Each monomer has six carbon atoms, hence the ‘6,6’ designation. The reaction is:

尼龙-6,6 由 1,6-己二胺与 1,6-己二酸合成。每个单体都有六个碳原子，因此得名‘6,6’。反应为：

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

Proteins are natural polyamides formed from amino acid monomers via condensation polymerisation. Each amino acid contains an amine group (–NH₂) and a carboxyl group (–COOH), and peptide bonds form between them.

蛋白质是天然聚酰胺，由氨基酸单体通过缩合聚合而成。每个氨基酸含有一个氨基（–NH₂）和一个羧基（–COOH），它们之间形成肽键。

7. Natural Polymers: DNA | 天然聚合物：DNA

DNA (deoxyribonucleic acid) is a natural condensation polymer. Its monomers are nucleotides, which consist of a phosphate group, a sugar (deoxyribose), and a nitrogenous base.

DNA（脱氧核糖核酸）是一种天然缩合聚合物。其单体为核苷酸，由一个磷酸基团、一个糖（脱氧核糖）和一个含氮碱基组成。

The sugar and phosphate groups alternate to form the polymer backbone via phosphodiester bonds, while the bases pair up in the centre. The formation of each phosphodiester bond releases a water molecule, confirming condensation polymerisation.

糖与磷酸基团交替排列，通过磷酸二酯键形成聚合物骨架，而碱基在中间配对。每个磷酸二酯键的形成都会释放一个水分子，确认为缩合聚合。

OCR candidates are expected to recognise DNA as a polymer and understand that its structure arises from condensation reactions between nucleotides – not to memorise detailed base sequences.

OCR 考生需要识别 DNA 是一种聚合物，并理解其结构由核苷酸之间的缩合反应构建而来，而不需记忆详细碱基序列。

8. Thermosoftening vs Thermosetting Plastics | 热塑性塑料与热固性塑料

Polymers can be classified by their behaviour when heated. Thermosoftening (thermoplastic) polymers soften on heating and harden when cooled, because their polymer chains are held by weak intermolecular forces that can be overcome by heat.

聚合物可根据受热行为分类。热塑性（热软化）聚合物加热变软、冷却变硬，因为其分子链由较弱的分子间作用力维系，加热即可克服。

Thermosetting polymers do not melt or soften when heated. They have strong cross-links between polymer chains, forming a rigid, permanent 3D network. Once set, they cannot be reshaped and will char on strong heating.

热固性聚合物加热时不熔化也不软化。它们分子链之间有牢固的交联，形成刚硬、永久的三维网络。一旦定型便无法重塑，强热下会碳化。

Examples of thermoplastics: poly(ethene), poly(propene), PVC, nylon (can be melt-spun).

热塑性塑料举例：聚乙烯、聚丙烯、PVC、尼龙（可熔融纺丝）。
Examples of thermosets: melamine, epoxy resins, vulcanised rubber.

热固性塑料举例：三聚氰胺、环氧树脂、硫化橡胶。

9. Environmental Issues | 环境问题

Most synthetic addition polymers are non-biodegradable because they lack reactive functional groups and cannot be broken down by microorganisms. This leads to long-lasting landfill waste and plastic pollution in oceans.

大多数合成加成聚合物不可生物降解，因为它们缺少活泼官能团，不能被微生物分解。这导致了持久的填埋废物和海洋塑料污染。

Burning waste plastics can release toxic gases such as carbon monoxide (incomplete combustion) and hydrogen chloride from PVC, as well as contributing to greenhouse gas emissions.

焚烧废弃塑料会释放有毒气体，例如一氧化碳（不完全燃烧）以及来自 PVC 的氯化氢，同时增加温室气体排放。

Biodegradable polymers, such as polylactic acid (PLA) made from corn starch, are designed to break down under specific conditions. OCR may ask you to compare their environmental impact with that of traditional plastics.

可生物降解聚合物，如用玉米淀粉制成的聚乳酸（PLA），被设计成在特定条件下分解。OCR 可能要求你比较它们与传统塑料的环境影响。

10. Recycling and Disposal | 回收与处置

Recycling methods for polymers include mechanical recycling (grinding and remelting thermoplastics), chemical recycling (breaking down the polymer into monomers), and energy recovery (incineration with electricity generation).

聚合物的回收方法包括机械回收（粉碎并重新熔融热塑性塑料）、化学回收（将聚合物分解为单体）以及能量回收（焚烧发电）。

Sorting is crucial because different polymers have different properties and melting points. Resin identification codes (1-7) help identify plastic types such as PET (1), HDPE (2), and PVC (3).

分类至关重要，因为不同聚合物具有不同的性质和熔点。树脂识别码（1-7）有助识别塑料类型，如 PET（1）、HDPE（2）和 PVC（3）。

Reusing plastics and reducing single-use packaging are more sustainable options that reduce demand for raw materials and energy.

重复使用塑料和减少一次性包装是更可持续的选择，可以降低对原材料和能源的需求。

11. Summary Table of Polymer Types | 聚合物类型总结表

The following table compares key features of addition and condensation polymers, helping you answer typical OCR questions.

下表对比了加成聚合物和缩合聚合物的关键特征，帮助你回答 OCR 典型问题。

Feature	Addition Polymerisation	Condensation Polymerisation
Monomers	Alkenes (C=C bond)	Two monomers with two functional groups each (e.g. diol + diacid)
Small molecule lost?	No	Yes, usually water or HCl
Polymer backbone	C–C chain	Contains ester or amide linkages
Examples	Poly(ethene), PVC, PTFE	PET (polyester), nylon, DNA, proteins
Biodegradability	Generally non-biodegradable	Some are biodegradable (e.g. PLA, natural polymers)

12. Exam Tips for Polymer Questions | 聚合物考题应试技巧

When identifying the monomer from an addition polymer, find the repeating unit and restore the double bond between the carbon atoms.

从加成聚合物识别单体时，找到重复单元并在碳原子之间恢复双键。
For condensation polymers, look for ester or amide links and split accordingly to recover the two monomers, remembering to add back the lost small molecule (usually water).

对于缩合聚合物，寻找酯键或酰胺键并相应分割，以恢复两个单体，记得补回失去的小分子（通常是水）。
Draw the repeating unit with open bonds at both ends; never include the ‘n’ inside the bracket when showing the repeating unit on its own.

绘制重复单元时两端画出开放键；单独展示重复单元时切勿在括号内写上‘n’。
Learn the structure of a nucleotide (phosphate–sugar–base) and be able to state that DNA forms by condensation polymerisation.

学习核苷酸的结构（磷酸-糖-碱基），并能说明 DNA 是通过缩合聚合形成的。
Compare thermoplastics and thermosets by referring to intermolecular forces and cross-links, not just “melts” or “doesn’t melt”.

比较热塑性塑料与热固性塑料时，要从分子间力与交联角度解释，而不仅仅是“熔化”或“不熔化”。

Published by TutorHao | Chemistry Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）

GCSE OCR Chemistry: Polymers – Exam-Focused Revision | GCSE OCR 化学：聚合物 考点精讲