高分子化学总复习.ppt

Polymer Chemistry Review,Shuizhu Wu 2010.11.25,答疑安排： 赵建青 25-101 吴水珠 25-514 刘述梅25-317、25-504 刘海敏 13-204 张安强 25-530 12月3日 上午9:00 11:30 下午3:00 5:00(部分),题型,名词解释 10分 5小题 填空 12分 6小题 选择题 18分 6小题 问答题 35分 7小题 计算题 25分 5小题,Chapter 1 Introduction,Basic concepts DP（聚合度）: 聚合物的结构单元数（或重复单元数）。 Chain segment（链节）：结构单元俗称为链节。 homopolymer(均聚物)：由一种单体进行聚合所得的聚合物。 copolymer(共聚物)：由两种或多种单体同时参与聚合所得的聚合物。 thermoplastic polymer(热塑性聚合物)：热塑性是指一般线型或支链型聚合物具有可反复加热软化或熔化而再成型的性质，具备热塑性的聚合物称作热塑性聚合物。 thermosetting polymer (热固性聚合物)：热固性是指交联聚合物一次成型后，加热不能再软化或熔化而重新成型的性质，具有这种性质的聚合物称作热固性聚合物。 kinetic chain length(动力学链长)：动力学链长是指每个活性中心自引发至终止平均所消耗的单体分子数,2. Classification and nomenclature of polymers（聚合物的分类和命名） 3. Polymerization 4. Molecular weight and its distribution 5. Microstructure 6. Linear, branched and crosslinked polymers 7. Aggregate structure 8. Mechanical properties.,Key points: Whats the difference between macromolecule and low-molecular-weight compounds? high molecular weight, repeat unit 分子量大，由许多相同的结构单元经共价键重复连接而成 molecular weight polydispersity and structure polydispersity分子量多分散性和结构多分散性 Different units 有几种运动单元 microstructure 结构复杂，有一次、二次和三次结构。一次结构是指大分子链中的结构单元或相邻结构单元的立体排布。二次结构是指单个分子链的构象或聚集态类型。三次结构是指高分子聚集体中大分子链的排列情况。,Whats the difference between thermoplastic resin and thermoset? Thermoplastic: Becoming soft when heated and hard when cooled 聚合物具有的可反复加热软化或熔化而再成型的性质 Thermoset: A thermoset material cannot be melted and re-shaped after it is cured 交联聚合物一次成型后，加热不能再软化或熔化而重新成型的性质,How to distinguish rubber, fiber and plastic? 橡胶分子的柔性大，分子间作用力小；纤维常为结晶性聚合物，分子间作用力大；塑料的分子间作用力介于二者之间。,分子量的计算,其中ni, mi, Mi分别代表i-聚体的分子数、质量和分子量。 MiDPMru,Chapter 2 Free radical polymerization,Monomers suitable for radical polymerization most of the vinyl monomers are suitable except for 1,1-dicyanoethylene nitroethylene 2. Mechanism of radical polymerization Initiation 链引发 Propagation 链增长 Termination 链终止 chain transfer链转移,Characteristics of free radical polymerization: Sequence of events: initiation, propagation, termination, chain transfer 基元反应：链引发、链增长、链终止、链转移 As the reaction time is increased, DP (or molecular weight) varies little. 随反应时间的延长，分子量（聚合度）不变 The conversion increases as the reaction time is increased. 随反应时间的延长，单体浓度逐渐降低，聚合物浓度增加，转化率提高。 Small amount of retardant can terminate the polymerization 少量阻聚剂可使聚合终止,3. Initiators Azo type 脂肪族偶氮化合物 AIBN b. Peroxide 过氧化物 BPO c. Redox systems 氧化还原体系 t1/2 = ln2/kd=0.693/kd,比较自由基聚合、阳离子聚合、阴离子聚合Ziegler-Natta聚合所用的引发剂的区别。 自由基聚合：易分解形成自由基的化合物 阳离子聚合：一般为Lewis酸类化合物 阴离子聚合：一般为Lewis碱类化合物 Ziegler-Natta聚合：主引发剂为Lewis酸类化合物，共引发剂为Lewis碱类化合物，但它不是阳离子聚合和阴离子聚合引发剂的简单加合。,Rate of initiation: Ri=kdI Initiator efficiency f: the fraction of radicals formed in the primary step of initiator decomposition which are successful in initiating polymerization. 引发聚合部分的引发剂占引发剂分解或消耗总量的分率,Initiator efficiency The induced decomposition of initiator 引发剂的诱导分解，徒然消耗引发剂，降低引发剂效率 The presence of solvent (or monomer) cage which traps the radicals for some period before they diffuse apart 笼蔽效应 and other side reactions 其他副反应,4. Kinetics of free radical polymerization Three assumptions: A. KP and Kt are independent of the size of the radical, namely equivalence of reactivity for propagating chain radicals 等活性假定，链自由基的活性与链长无关 B. Steady-state assumption: the concentration of radicals increases initially, but almost instantaneously reaches a constant, steady-state value. Ri=Rt 稳态假设 C. high DP, the amount of monomers used for initiation is far less than that for propagation, Ri RP 聚合度很大,Polymerization rate expression:,Autoacceleration: As the polymerization proceeds the viscosity of the system increases and termination becomes increasingly slower. High viscosity affects termination much more than propagation. Therefore, the quantity kP/kt1/2 increases, the result is an increase in RP and molecular weight. 自动加速效应的本质：双基终止,DP and molecular weight the average number of monomer molecules consumed (polymerized) per each radical which initiates a polymerization chain. 每个活性种从引发阶段到终止阶段所消耗的单体分子数。 1/DP = 1/DP0 + CTT/M 1/Xn= 1/Xn0 + CTT/M (存在链转移反应） Chain transfer reactions Vinyl chloride DP depends on T 通用聚氯乙烯的聚合度一般仅由温度来控制，聚合速率或时间则由引发剂浓度来调节。,Inhibition and retardation Inhibitors stop every radical and polymerization is completely halted until they are consumed.阻聚使反应停止 Retarders are less efficient and stop only a portion of the radicals. 缓聚使反应速率减小,5. Thermodynamics Equilibrium monomer concentration The ceiling temperature at which the propagation and depropagation rates are equal. Upper temperature limit above which polymer cannot be obtained even from pure monomer. The ceiling temperature ( 当Me=1 M时，聚合和解聚处于平衡状态的平衡温度) 聚合上限温度,Chapter 3 Chain copolymerization,Types of copolymers: Statistical (Random) 无规 Block 嵌段 Graft 接枝 Alternating 交替,2. Copolymerization equation Reactivity ratios 竞聚率是均聚增长和共聚增长的速率常数的比值,Copolymer equation,3. Types of copolymerization behavior 以下各竞聚率的含义是什么？ r1 = 0 自由基1不能与同种单体均聚，只能共聚 r1 = 1 自由基1加成同种或异种单体的难易程度相同，均聚和共聚的高铝相同 r1 1 自由基1容易进行均聚 r1 = 自由基1不能共聚，只能均聚,ideal copolymerization r1r2=1 r1r2=1， 共聚物组成与单体组成相等 Alternating copolymerization: r1=r2=0 r11, r21, r21),4. Reactivities of monomer and radical 会利用竞聚率判断单体、自由基的相对活性（注意同一参照物） r1=0.3, r2=1.5: 活性M1 M2 5. Effects of substituents on the reactivities of monomer and radical Resonance effect The order of monomer reactivities corresponds to the order of increased resonance stabilization by the particular substituent of the radical formed from the monomer.,The order of substituents in enhancing radical reactivity is the opposite of their order in enhancing monomer reactivity. Polar effects Resonance effects polar effects 取代基对自由基活性的影响比对单体活性的影响要大得多。,6. Q-e scheme Q describes the resonance factor e describes the polar factor(吸电子基团，正值） Ideal copolymerization occurs between two monomers having similar Q and e values, for example, styrene-1,3-butadiene, vinyl chloride-vinyl acetate, and acrylonitrile-methyl acrylate. The tendency toward alternation is greatest for monomers having similar Q values with high e values of opposite sign, e.g. styrene and maleic anhydride,Chapter 4 Polymerization Processes,Comparison of four polymerization methods Aside from the physical difference between the emulsion and other polymerization processes, there is one very significant kinetic difference: both high molecular weights and high reaction rates can be simultaneously attained,本体聚合：定义，特征 溶液聚合：定义，特征 悬浮聚合：定义，特征 乳液聚合：定义，特征 乳液聚合的组成，规律？,Chapter 5 Ionic polymerization,Cationic polymerization is limited to those monomers with electron-releasing substituents such as alkoxy, phenyl, vinyl and 1,1-dialkyl for example, butylene, alkoxy alkene, conjugated alkene Anionic polymerization takes place with monomers possessing electro-withdrawing groups such as nitrile, carboxyl, phenyl, and vinyl 共轭烯烃类单体可进行自由基、阳离子、阴离子聚合,会判断哪些单体能进行自由基、阳离子、阴离子聚合 根据反应条件中给出的引发剂种类即能判断聚合反应是自由基、阳离子或阴离子聚合 Cationic polymerization: Lewis酸 Lewis acid Anionic polymerization: Lewis碱 (alkali metal, metal alkyl),Living anionic polymerization why anionic polymerization can be “living”? 活性聚合物是指在链增长反应中，活性链直到单体全部耗尽仍保持活性的聚合物，再加入单体还可继续引发聚合，聚合的分子量继续增加。 在阴离子聚合反应中，带有相同电荷的活性链离子不能发生双基终止；活性链负碳离子的反离子常为金属离子，它一般不能夺取链中的某个原子或H+而终止；活性链通过脱去H-离子发生链终止又很困难，所以当体系中无引起链转移或链终止的杂质时，实际上是无终止聚合，即活性聚合。,Why autoacceleration will not occur in ionic polymerization? 活性增长种带电荷，同种电荷相斥，因此无双基终止，不会发生自动加速效应 why the rate of anionic polymerization is larger than that of radical polymerization? 活性增长种的浓度高；无终止。,离子对增长种的结合形式及其活性 In non-polar solvents, extensive association takes place at high butyllithium concentrations, the initiation and propagation rates are found to be proportional to only the 1/6 and 1/2 powers of butyllithium concentration respectively. This result has been interpreted in terms of the association equilibria with the initiator and propagating ion pairs in equilibria with the corresponding hexamer and dimer,会判断阴离子活性聚合用于制备嵌段共聚物时的单体加料顺序（从单体结构判断） Distinguishing between radical, cationic, and anionic polymerizations 如分子量和聚合时间的关系、引发剂、转化率和聚合时间的关系等,Ring-opening polymerization 环状单体在引发剂作用下形成线型聚合物的过程。 Polymerizability （容易开环聚合的程度）: 3, 4 8 7, 5 开环聚合的性质？,Chapter 6 Coordination polymerization,Composition of Ziegler-Natta catalysts （ Ziegler-Natta催化剂的组成） Ziegler-Natta catalysts are usually composed of main catalyst and co-catalyst: Compounds of Group IV-VIII transition metal: （主引发剂是IV-VIII族过渡金属化合物） Co-catalyst: Group I-III organometallic compounds （共引发剂I-III族有机金属化合物）,Ziegler-Natta catalysts: Lewis酸和Lewis碱，但不是简单的加合，而是能使单体通过配位聚合形成立构规整的聚合物,Polypropylene 配位聚合的意义，典型催化剂 Polyethylene 分类，典型催化剂,能判断给出的单体能否进行配位聚合 能形成哪些立构规整聚合物 是否具有旋光活性,Chapter 7 Step polymerization,Characteristics: 特征 Disappearance of monomer very early in the reaction far before the production of any polymer of sufficiently high molecular weight to be of practical utility. （单体在反应初期迅速消失，但聚合物的分子量需要较长时间才能达到满足应用的要求） Any two species in the reaction mixture can react with each other. （在反应体系中任何两个物种均可互相反应） Polymerization rate is the sum of the rates of reaction between molecules of various sizes. （聚合速率是不同大小的物种之间互相反应的速率之和）,Control of molecular weight is important in linear condensation polymerization. （分子量控制是线形缩聚的关键） Control of gel point is important in crosslinked condensation polymer structure. （凝胶点的控制是体形缩聚的关键）,会判断给出的单体对能否缩聚成为高聚物（成环） The general order of thermodynamic stability of different sized ring structures is: （不同大小的环结构的热力学稳定性顺序如下） n = 3,4,8 to 11 7, 12 and larger 5 ,6 自由基聚合和逐步聚合的比较 如转化率、分子量等,For the polymerization of the bifunctional monomers aAa and bBb (e.g, diol and diacid or diamine and diacid), the numbers of a and b functional groups are given by Na and Nb respectively. （二元酸aAa和二元醇bBb进行缩聚，设Na 和 Nb为a、b的起始基团数，分别为两种单体分子数的2倍） r = Na/Nb r 1,aAa plus bBb polymerization (stoichiometric balance) with the addition of small amounts of a monofunctional reactant Cb. （ aAa 和 bBb两种单体等基团数，另加微量单官能团物质Cb ）,Polymerization of aRb type monomers (internally supplied stoichiometry) with the addition of small amounts of monofunctional monomer Cb. 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