聚合物化学翻译_第一章

BASIC CONCEPTS

A polymer is a large molecule built up from numerous smaller molecules. These large molecules may be linear, slightly branched, or highly interconnected. In the latter case the structure develops into a large three-dimensional network.

聚合物是由数目众多的较小分子构造而成的一种大分子。这些大分子可以是线型的、简单的支链型的、或者是高度相互交联的。后者的结构发展成一种三维网状结构。

The small molecules used as the basic building blocks for these large molecules are known as monomers. For example the commercially important material poly(vinyl chloried) is made from the monomer vinyl chloride. The repeat unit in the polymer usually corresponds to the monomer from which the polymer was made. 构成大分子中基本单元的小分子被称为单体。例如，具有重要商业用途的聚氯乙烯是由氯乙烯单体制成的。聚合物中的重复结构单元常常相当于制成聚合物的单体。

P1-2 There are exceptions to this, though. Poly(vinyl alcohol) is formally considered to be made up of vinyl alcohol (CH2CHOH) repeat units but there is , in fact, no such monomer as vinyl clcohol.

虽然也有例外。聚乙烯醇一般会被认为是由乙烯醇这种重复单元制成的，但是，事实上没有乙烯醇这样一种单体。

The appropriate molecular unit exists in the alternative tautomeric form, ethanal CH3CHO. To make this polymer, it is necessary first to prepare poly(vinyl ethanoate) from the monomer vinyl ethanoate, and then to hydrolyse the product to yield the polymeric alcohol.

相应的分子单元以互变异构的形式-乙醛存在。为了制备聚乙烯醇，必需先由乙酸乙烯酯单体制备出聚乙酸乙烯酯，然后对产品进行水解最终制成聚乙烯醇。

The size of a polymer molecule may be defined either by its mass (see Chapter 6) or by the number of repeat units in the molecule. This latter indicator of size is called the degree of polymerization, DP. The relative molar mass of the polymer is thus the product of the relative molar mass of the repeat unit and the DP.聚合物分子的尺寸既可以被定义为它的质量也可以被定义为它的分子重复单元的数量。后者被称为聚合度。因此聚合物的相对分子质量是重复单元和聚合度的相对摩尔质量的产物。

There is no clear cut boundary between polymer chemistry and the rest of chemistry. As a very rough guide, molecules of relative molar mass of at least 1000 or a DP of at least 100 are considered to fall into the domain of polymer chemistry.

在聚合物化学和其它化学之间不存在严格的界线。作为一个粗陋的指标，分子的相对分子量至少达到1000或聚合度至少100被认为是聚合物化学的范畴。

The vast majority of polymers in commercial use are organic in nature, that is they are based on covalent compounds of carbon. This is also true of the silicones which, though based on silicon-oxygen backbones, also generally contain significant proportions of hydrocarbon groups. 商业中聚合物的绝大多数分子在性质上是有机分子，也就是说这些聚合物是基于碳原子的共价键化合物。对于硅氧烷聚合物也是如此，尽管它们以硅-氧键为主链，一般也含有大量的烷烃基团。

The other elements involved in polymer chemistry most commonly include hydrogen, oxygen, chlorine, fluorine, phosphorus, and sulfur, i.e. those elements which are able to form covalent bonds, albeit of some polarity, with carbon.

在聚合物化学中其它的元素包括氢、氧、氯、氟、磷和硫，它们中有些是极性元素，但都能

与碳形成共价键。

As is characteristic of covalent compounds, in addition to primary valence forces, polymer molecules are also subject to various secondary intermolecular forces. This include dipole forces between oppositely charged ends of polar bonds and dispersion forces which arise due to perturbations of the electron clouds about individual atoms within the polymer molecule.

作为共价键化合物的特性，除了有主价键力之外，聚合物分子也拥有多种第二分子间作用力。这种分子间力包括极性键相反电荷未端的极性力，以及色散力，色散力来源于聚合物分子内单个原子间电子云的扰动。

Hydrogen bonding, which arises from the particularly intense dipoles associated with hydrogen atoms attached to electronegative elements such as oxygen or nitrogen, is important in certain polymers, notably proteins. Hydrogen bonds have the effect of fixing the molecule in a particular orientation. These fixed structures are essential for the specific functions that proteins have in the biochemical processes of life.

氢原子靠近电负性元素如氧或氮，会具有特别强的偶极，由此产生氢键，氢键对有些聚合物比如蛋白质极为重要。氢键具有把分子固定在某个特定取向上的作用。这种固定结构至使蛋白质在生命的生物化学过程中承担起特殊功能是十分必要的。

THE HISTORY OF THE CONCEPT OF THE MACROMOLECULE

Modern books about polymer chemistry explain that the word polymer is derived from the Greek words ‘poly’ meaning many an ‘meros’ m eaning part. They often then infer that it follows that this term applies to giant molecules built up of large numbers of interconnected monomer units. In fact this is misleading since historically the word polymer was coined for other reasons.

关于聚合物化学的现代书藉解释聚合物（polymer ）这个词汇是洐生于希腊单词‘poly’，它的意思是很多，单词‘meros’意思是部分。然后这些书推断跟随聚合物这个术语意味着巨大的分子，由大量的相互连接的分子单元构建而成。事实上这是个误解，聚合物这个单词在历史上是为其它原因而构造出来的。

The concept of polymerism was originally applied to the situation in which molecules had identical empirical formulae but very different chemical and physical properties. For example, benzene (C6H6; empirical formula also CH) was considered to be a polymer of acetylene (C2H2; empirical formula also CH). Thus the word ‘polymer’is to be found in textbooks of organic chemistry published up to about 1920 but not with its modern meaning. 起初聚合的概念被应用于这样的场景，分子具有相同的经验分子式但化学性质和物理性质极其不同。例如，苯(C6H6; 经验分子式CH)被认为是乙炔的聚合物‘polymer’。（C2H2;经验分子式CH ）因此聚合物‘polymer’这个单词在约1920年以前的有机化学教科书中一直都能找到，但却不是现代这个含义。

The situation is confused, however, by the case of certain chemicals. Styrene, for example, was known from the mid-nineteenth century as a clear organic liquid of characteristic pungent odour. 可这在特定化学里是种被混淆的情形。例如苯乙烯从十九世纪中期就被认定是一种带特殊刺激性气味的纯粹的有机液体。

It was also known to convert itself under certain circumstances into a clear resinous solid that was almost odour-free, this resin then being called metastyrene. The formation of metastyrene （介苯乙烯）from styrene was described as a polymerisation and metastyrene was held to be a polymer of styrene.

也知道苯自身在一定环境下会转化成没有气味的纯粹的树脂状固体。由苯乙烯制得介苯乙烯

的形成过程被定义为聚合，且介苯乙烯被称作是苯乙烯的聚合物。

P3-0 However these terms applied only in the sense that there was no change in empirical formula despite the very profound alteration in chemical and physical properties. There was no understanding of the cause of this change and certainly the chemists of the time had no idea of what had happened to the styrene that was remotely akin to the modern view of polymerisation. 可是这些术语仅仅被用在经验分子式不发生变化的情况下，虽然在化学性质和物理性质上有深刻的改变。改变的原因无从理解，且那个时代的化学家无法想象苯乙烯到底发生了什么变化，这与相似于现代观念中的聚合是如此的遥远。

Understanding of the fundamental nature of those materials now called polymers had to wait until the 1920s, when Herman Staudinger coined the word ‘macromolecule’ and thus clarified thinking. There was no ambiguity about this new term –it meant ‘large molecule’, again from the Greek, and these days is used almost interchangeably with the word polymer. Strictly speaking, though, the words are not synonymous.

要理解现在被称为聚合物的这些物质的基本属性还必须等到十九世纪二十年代，在那时Staudinger造了个新单词‘macromolecule’大分子以正视听。这个新单词的意思是大的分子，这样就不会模棱两可了，‘macromolecule’也来自于希腊语，并且今天也和’polymer ‘这个单词互换使用。从严格意义上说，这两个单词并不是同义词。

P3-1 There is no reason in principle for a macromolecule to be composed of repeating structural units; in practice, however, they usually are. Staudinger’s concept of macromolecules was not at all well received at first. His wife once recalled that he had ‘encountered opposition in all his lectures’.

从原理上说没有理由认为大分子一定是重复结构单元组成的，可是，大分子的确常常如此。Staudinger的大分子概念起初并未很好的被人们接受。一次他的妻子回忆过去，说他在所有的讲座中遭到反对。

Typical of this opposition was that of one distinguished organic chemist who declared that it was as if zoologists ‘were told that somewhere in Africa an elephant was found who was 1500 feet long and 300 feet high’.

反对者的一个典型例子是，某位著名有机化学家他声称，大分子好比动物学家们被告知在非洲发现一头大象，它有1500英尺长300英尺高。

There were essentially three reasons for this opposition. Firstly, many macromolecular compounds in solution behave as colloids. Hence they were assumed to be identical with the then known inorganic colloids. This in turn implied that they were not macromolecular at all, but were actually composed of small molecules bound together by ill-defined secondary forces.

有三个关键原因致使这些反对态度。首先很多大分子在溶液中的表现很象胶体。因此，他们被认这与已知的无机胶体是相同的东西。反过来这又暗示着他们完全不是大分子，而实际上是由定义不清的第二分子间力结合在一起的小分子组成。

Such thinking led the German chemist C. D. Harries to pursue the search for the ‘rubber molecule’ in the early years of the twentieth century. He used various mild degradations of natural rubber, which he believed would destroy the colloidal character of the material and yield its constituent molecules, which were assumed to be fairly small. He was, of course, unsuccessful.

这种思潮影响德国化学家Harries在二十世纪早期去寻找所谓的’橡胶分子’。他使用各种各样天然橡胶的温和的降解物，在其中他相信破坏了材料的胶体性质并且生成了胶体的组成分子，此组成分子被认为是非常小的。当然，他不会成功。

The second reason for opposition to Staudinger’s hypothesis was that it meant the loss of the

concept of a single formula for a single compound. Macromolecules had to be written in the form (CH2CHX)n, where n was a large number. Moreover, no means were available, or indeed are available, for discretely separating molecules where n=100 from those where n=101.

反对Staudinger假说的第二个原因是，这意味着失去单个分子式对单个化合物的概念。大分子必须被写成(CH2CHX)n的形式，这里的n是个很大的数字。而且，无法得到平均值，或实在为了得到平均值，要把n=100的分子与n=101的分子离散的区分开来。

Any such attempted fractionation always gives a distribution of values of n and, even if the mean value of a fraction is actually n=100, there are significant numbers of molecules of n=99, n=101, and so on.

任何这种尝试性的分布总是给出n值的分布，即便是某一部分的平均值就是n=100，也仍然有相当一部分分子的n=99, n=101等等。

Now the concept of one compound, one formula, with one formula being capable of both physical (i.e. spatial) and chemical interpretation, had been developed slowly and at some cost, with many long, hard-fought battles. Organic chemists could not easily throw it out, particularly in view of the fact that it had been so conspicuously successful with much of the rest of organic chemistry.

现在一种化合物对应一种分子式、和一种分子式可以是物理（如：空间的）和化学的两种解释的概念，以某种代价伴随着严峻的争论，缓慢的发展起来了。有机化学家不会轻易地抛弃这种观点，部分原因是从实际的观察出发，这种观点在其它有机化学中绝大多数化合物是极其成功的。

The third reason for opposition lay in the nature of many of the polymeric materials then known. Not only were they apparently ill-characterised, but they were also frequently non-crystalline, existing as gums and resins. Just the sort of unpromising media, in fact, from which dextrous organic chemists had become used to extracting（萃取）crystalline substances of well characterised physical and chemical properties.

反对者的第三个原因在于后来才得知的聚合物材料的许多属性。不仅表现出聚合物难以表征，而且它们也常常不能结晶，以胶状物和树脂状存在。事实上，正是这种没有前途的介质，聪明伶俐的有机化学家们从中习惯于萃取、结晶物质来表征物理和化学性质。

To accept such resins as inherently non-crystallisable and not capable of purification in the traditional sense of the word was too much for the self-esteem of many professional organic chemists.

对于自以为是的许多资深有机化学家来说，要接受这样一种本质上不可结晶，在传统意义上不能纯化的树脂，是要求太高了。

P4-2 Staudinger’s original paper opposing the prevalent colloidal view of certain organ ic materials was published in 1920 and contained mainly negative evidence. Firstly, he showed that the organic substances retained their colloidal nature in all solvents in which they dissolve; by contrast, inorganic colloids lose their colloidal character when the solvent is changed. Staudinger的原创论文发表于1920年，其中反对了有机材料方面流行的胶体观点并包含了主要的否定性的证据。首先，他展示了有机物质在所有溶解它们的溶剂中会保留胶体的性质；与之相反，无机胶体在溶剂改变的情况下会失去它们的胶体性质。

Secondly, contrary to what would have been expected, colloidal character was able to survive chemical modification of the original substance.

第二，与所期望的相反，胶体的性质在有机物质的化学修饰中存留下来。

By about 1930 Staudinger and others had accumulated much evidence in favour of the

macromolecular hypothesis. The final part in establishing the concept was carried out by Wallace Carothers of the Du Pont company in the USA. He began his work in 1929 and stated at the outset that the aim was to prepare polymers of definite structure through the use of established organic reactions.

大约到了1930年Staudinger和其它学者收集了大量符合大分子假说的证据。在建立大分子概念的最后一个部分是于美国杜邦公司的Carothers 完成的。Carothers 于1929年开始他的研究工作，并声明研究工作的开端，以利用确定的有机反应制备具有明确结构的聚合物为目的。

Though his personal life was tragic, Carothers was an excellent chemist who succeeded brilliantly in his aim. By the end of his work he had not only demonstrated the relationship between structure and propertied for a number of polymers, but he had invented materials of tremendous commercial importance, including neoprene rubber（氯丁橡胶）and the nylons.

虽然Carothers 的人生是一场悲剧，但在实现他目标的过程中取得了辉煌的成功，是一位杰出的化学家。到他工作的后期，他不仅证明了许多聚合物的结构与性能之间的相互关系，而且他发明出了数量极多的具有重要商业价值的聚合物材料，其中包括氯丁橡胶和尼龙。

CLASSIFICATION OF POLYMERS

There are a number of methods of classifying polymers. One is to adopt the approach of using their response to thermal treatment and to divide them into thermoplastics and thermosets. Thermorplastics are polymers which melt when heated and resolidify when cooled, while thermosets are those which do not melt when heated but, at sufficiently high temperatures, decompose irreversibly.

聚合物有多种分类方法。一种方法是采用它们对热处理的不同反眏为途径进行分类，可以把它们分成热塑性塑料和热固性塑料。热塑性塑料是加热时熔化冷却时固化的聚合物，而热固性塑料是加热时不熔化但温度足够高时发生不可逆的分解的聚合物。

This system has the benefit that there is a useful chemical distinction between the two groups. Thermoplastics comprise essentially linear or lightly branched polymer molecules, while thermosets are substantially crosslinked materials, consisting of an extensive three-dimensional network of covalent chemical bonding.

这种分类的好处在于这两个集团之间存在有用的化学区别。热塑性塑料必然包含线型的功高度支化的聚合物分子，热固性塑料实质上是交联的材料，包括有大范围的三维网络状化学共价键。

Another classification system, first suggested by Carothers in 1929, is based on the nature of the chemical reactions employed in the polymerisation. Here the two major groups are the condensation and the addition polymers.

另一个分类体系，是Carothers于1929年首次提出的，基于在聚合过程中使用的化学反应性质。这里两个主要的集团就是缩合聚合物和加成聚合物。

Condensation polymers are those prepared from monomers where reaction is accompanied by the loss of a small molecule, usually of water, for example polyesters which are formed by the condensation shown in Reaction 1.1.

缩合聚合物是那些由单体制备反应中伴随着小分子的失去，通常小分子就是水分子，例如，聚酯由反应式1.1所示于缩合反应形成。

By contrast, addition polymers are those formed by the addition reaction of an unsaturated monomer, such as takes place in the polymerisation of vinyl chloride (Reaction 1.2).

与之不同，加成聚合物是由不饱和单体的加成反应形成的，例如在氯乙烯中发生的聚合反应。

This system was slightly modified by P. J. Flory, who placed the emphasis on the mechanisms of the polymerisation reactions. He reclassified polymerisations as step reactions or chain reactions corresponding approximately to condensation or addition in Carothers’s scheme, but not completely.

这个系统由Flory进行了细微的改造，他强调了聚合反应的机理。他把聚合反应分为逐步聚合反应或链式聚合反应，与之相近似的是Carothers体系中的缩合反应或加成反应，但是它们并不是完全相同的。

A notable exception occurs with the synthesis of polyurethanes, which are formed by reaction of isocyanates with hydroxy(-OH) compounds and follow ‘step’ kinetics, but without the elimination of a small molecule from the respective units (Reaction 1.3).

著名的例外发生在聚氨酯的合成中，它由异氰酸酯和带有羟基的化合物反应制成且反应动力学遵循“逐步”的过程，但在各个单元上又不消去小分子。

P6-1 In the first of these, the kinetics are such that there is a gradual build up of high relative molar mass material as reaction proceeds, with the highest molar mass molecules not appearing until the very end of the reaction. On the other hand, chain reaction, which occur only at a relatively few activated sites within the reacting medium, occur with rapid build up of a few high relative molar mass molecules while the rest of the monomer remains unreacted.

首先，随着反应的进行这种动力学存在较高分子量的物质逐步构建的过程，不到反应的最后阶段不会出现最高的分子量。另一方面，链式反应，它仅发生在相对量极小的反应环境的活性点上，极为迅速的构建出一些高分子量的分子，与此同时其它单晶体仍然还没有反应。When formed, such macromolecules stay essentially unchanged while the rest of the monomer undergoes conversion. This means that large molecules appear very early in the polymerisation reaction, which is characterised by having both high relative molar mass and monomer molecules present for most of the duration of the reaction.

这些大分子一旦形成就一成不变的呆在那儿此时其它单体经历转化反应。这意味着在聚合反应中大分子很早就出现了，这可以由高的相对分子量和反应持续时间的大多数情况下单体分子一直存在两方面得以证实。

P6-2 Step reactions can give molecules having a variety of morphologies（形态）from the simple unbranched linear to the heavily crosslinked network. The final structure depends on the number of functional groups in the parent monomers –the greater the proportion with a functionality of greater than two, the more extensive will be the branching until, at sufficient

degrees of branching, a highly crosslinked network emerges.

逐步反应能给出具有多种多样的分子形态，从简单的无支链的线型到高度交联的网状分子。最终的结构信赖于在父系单体中官能团的数目-官能团大于2的分子比例越多，支化的密度越大，达到足够大的支化度，就会出现高度交联的网状结构。

Chain reactions, by contrast, give only linear or lightly branched polymers. Thus, in terms of the thermoplastic/thermoset classification, chain reactions give thermoplastics, while step reactions may give either therm与之相反，链式反应，只能产生线型聚合物和轻度支化的聚合物。因此，根据热塑性塑料和热固性塑料的分类，链式反应只能产生热塑性塑料，而逐步反应即可以产生热塑性塑料也可以产生热固性塑料。

oplastics or thermosets.

STRUCTURE AND PROPERTIES OF POLYMERS

P6-3 Having established the basic principles of classification in polymer chemistry, we will now turn our attention to individual polymers and consider a little about their physical and chemical properties. Most of the examples which follow are of commercial importance, though it is their properties that are emphasised rather than the complete chemistry of their industrial manufacture.

在聚合物化学中已经建立起基本的分类原理，现在我们将把注意力转向各个聚合物且基本不考虑它们的物理和化学性质。接下来的大多数例子有着商业上的重要性，虽然重点在于它们的性质而不是它们在工业制造上的完整的化学过程。

In terms of the classification systems just referred to, it is found that the polymers of major commercial importance tend to be the thermoplastics or addition polymers rather than the thermosets, and these will be dealt with first.

根据刚刚提及的分类体系，发现主要的重要商用聚合物倾向于是热塑性塑料或加聚物，而不是热固性塑料，那就先谈谈热塑性塑料。