第二章缩聚反应.pptx

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,第二章缩聚反应,3,聚合反应按聚合机理或动力学分类,(Based on polymerization mechanism or kinetics),:,连锁聚合(,Chain Polymerization,):活性中心(,Active Center,)引发单体,迅速连锁增长。,逐步聚合(,Step Polymerization,):无活性中心,单体中不同官能团间相互反应而逐步增长。,大部分缩聚属逐步机理,大多数烯类加聚属连锁机理,活性中心,(Reactive Center),自由基聚合（,Free-Radical Polymerization,）,阳离子聚合（,Cationic Polymerization,）,阴离子聚合（,Ani,onic,P,olymerization,）,2、1,引言,(Introduction),4,逐步聚合反应得种类,(,types of step polymerization),缩聚反应:,官能团间得缩合聚合反应,同时有小分子产生。如二元酸与二元醇得聚酯化反应,二元胺与二元酸得聚酰胺化反应。,Condensation polymerization:the process to form condensation polymer from functional monomers by the various condensation reactions、E、g、Polyesters formed from diacids and diols,polyamides formed from diamines and diacids、,聚酯化反应:二元醇与二元羧酸、二元酯、二元酰氯等反应。,Polyesterification:reactions between diols and diacids/diesters/diacylchlorides、,例,5,b,),聚加成,(Polyaddition),:,形式上就是加成,机理就是逐步,(Addition form,step mechanism),6,例,7,c,)开环反应:,部分为逐步反应,如水、酸引发己内酰胺得开环生 成尼龙,-6,。,Parts of ring-opening reaction belong to step reaction,e、g、,Water,acid initiated hexanolactams ring-opening reaction formed Nylon-6,。,H,+,8,d),氧化偶合:单体与氧气得缩合反应。如,2,6,二甲基苯酚和氧气形成聚苯撑氧,也称聚苯醚,PPO,。,Oxidative coupling:condensation reaction between monomers and oxygen,e、g、,PPO formed from 2,6-xylenol and oxygen、,8,2、2,缩聚反应,(Condensation Polymerization),1,)定义,(Definition),官能团间经多次缩合形成聚合物得反应,兼有缩合出低分子和聚合成高分子得双重含义,即缩合聚合得简称。如己二胺和己二酸合成尼龙,66,The reaction to form condensation polymer,from monomers by the various condensation reactions,together with the loss of small molecules、,9,大家应该也有点累了，稍作休息,大家有疑问的，可以询问和交流,特点(,Characteristics,),:,10,缩聚单体含有特征结构官能团,且缩聚物中留有特征官 能团,(Condensation monomer contain feature structure in functional group,and it remains in condensation polymer),;,有低分子副产物,如水、醇、胺等,(with byproduct like water,alcohols,amine),;,缩聚物分子量和单体分子量不成整数倍,(Polymers molecular weight is not integral,multiple of monomers),;,大多数为可逆反应和逐步反应,(Most of them are reversible and step reaction),。,11,2,)缩聚反应体系,(Polycondensation reaction system),官能度(,Functionality,f,):分子中能参与反应得官能团数,(the number of functional groups that participate in reaction)、,官能团(,Functional group,):,OH,NH,2,COOH,COOR,COCl,(CO),2,O,SO,3,H,1-n,官能度体系,(1-n functionality system),醋酸与乙醇得酯化反应,她们均为单官能团物质。,(Polyesters reaction between acetic acid and alcohol,each has monofunctional group),例,1-1,官能度体系,(1-1 functionality system),12,1-2,官能度体系,(1-2 functionality system),辛醇与邻苯二甲酸酐(,f,=2,)反应形成邻苯二甲酸二辛酯(,DOP formed from octanol and Phthalic anhydride,),。,例,1-n,官能度体系,将形成低分子物,(1-n functioality system will form low molecular weight matter),13,2-n,官能度体系,(2-n functionality system),单体有能相互反应得官能团,A,、,B,(如氨基酸、羟基酸等),可经自身缩聚形成类似得线形缩聚物。,(Monomers contain functional group A and B that can participate mutual exchange reaction、Linear polycondensation is formed by self-condensation of monomers),。,通式如下:,2,官能度体系,(2 functionality system),14,如二元酸和二元醇,生成线形缩聚物。,(Linear polycondensation formed from diacids and diols)、,通式如下:,2-2,官能度体系,(2-2 functionality system),naAa,+,nbBb,a,AB,n,b,+(2,n,-1),ab,2-2,或,2,官能度体系得单体进行缩聚,形成线形缩聚物,(Linear polycondensations are formed by condensation reaction of monomers in 2-2 or 2 functionality system),15,2-3,官能度体系,(2-3 functionality system),如邻苯二甲酸酐(官能度为,2,)与甘油(即丙三醇,官能度为,3,)或季戊四醇(官能度为,4,),除线形方向缩聚外,侧基也能缩聚,先形成支链,而后进一步形成体形结构,故称为体形缩聚。,In phthalic anhydride and glycerol or pentaerythritol system,except linear polycondensation,folk chain can be formed and then,tri-demensional,structure,it is called tri-demensional polycondensation、,16,3,)缩聚反应得分类,(Classification of polycondensation),根据体系官能度不同,(based on different functionality),可分:,缩合反应,(,Condensation,):,1-n,官能度体系,如乙酸乙酯、邻苯二甲酸二辛酯等。,线形缩聚,(,Linear Polycondensation,):,2-2,或,2,官能度体系,如涤纶聚酯、尼龙,-66,等。,体形缩聚,(,Tridimensional Polycondensation,):,2-3,、,2-4,、,3-3,等多官能度体系,至少有一单体含两个以上官能,团,如酚醛树脂、环氧树脂。,Monomer has only two reactive groups,polymer chain grows from two directions、Molecular weight and the viscosity of reaction system gradually grow up、The obtained linear polymer is soluble and fusible、,2、3,线形缩聚反应得机理,(Kinetics of Linear Condensation Polymerization),18,指缩聚过程中生成得产物可同时被反应中产生得小分子所降解,单体分子与聚合物分子之间存在可逆平衡得逐步聚合 反应。,如聚酯化反应:,19,（,2-1),20,c,)缩聚反应得平衡常数,(,Equilibrium Constant,K,),根据平衡常数,K,得大小,可将线,形,缩聚大致分为三类,(,Linear condensation can be divided into three classes according to the K value,),:,(,1,),K,值小,如聚酯化反应,K,4,副产物水对分子量影响很,大,(Polyester reaction,K,4,byproduct water has a,great influence on molecule weight),(,2,),K,值中等,如聚酰胺化反应,K 300,500,水对分子量,有所影响,(Polyamide reaction K 300500,water,has some influence on molecule weight),(,3,),K,值很大,在几千以上,如聚碳酸酯、聚砜,可看成不可,逆缩聚,(Polycarbonate or Polysulfone reaction with,K beyound several thousands,can be seemed as,inreversible reaction),d,)聚合度与反应程度,p,得关系,(Relationships between Degree of polymerization and extent of reaction),缩聚早期,单体很快消失,转变成二、三、四聚体,转化率就变得很高,而分子量逐步增加。所以研究缩聚过程中转化率并无实际意义,因此常用反应基团得,反应程度,来表述反应进行得深度。,In early condensation,monomers quickly reacted,converted to dimer,trimer,tetramer,conversion was high and molecular weight gradually grow up、So its no use to study conversion in condensation polymerization、Its more reliable to use extent of reaction of reactive group to reflect reaction depth、,例如:一种缩聚反应,单体间双双反应很快全部变成二聚体,就单体转化率而言,转化率达,100,;而官能团得反应程度仅,50,。,23,N,0,:体系中起始得羧基数(或羟基数),等于二元酸和二元醇得分子总数,也等于反应时间,t,时所有大分子得结构单元数。,N,:反应到,t,时体系中残留得羧基数(或羟基数),等于大分子数。,平均聚合度为大分子链得平均总单体数(或结构单元数),即:,反应程度(,extent of reaction,p,)?,(2-2),24,反应程度,p,:已反应得官能团数占起始官能团数得分率。,(2-3),聚合物和反应程度得关系,25,体系中得羟基数或羧基数,N,0,为:,1x2=2mol,因此结构单元数也为,2mol,。,若反应,t,时间后体系中残存得羧基数,N,为,0、5mol,则大分子数:,0、5mol,(有一个羧基,就有一条大分子)。,所以:,例,注 意,26,27,缩聚过程中得副反应,(Secondary reaction in condensation),除环化反应外,还可能发生如下副反应,:,(,a),官能团得消去反应,(Elimination reaction of functional groups),包括羧酸得脱羧、胺得脱氨等反应,如:,HOOC(CH,2,),n,COOH,HOOC(CH,2,),n,H+CO,2,(,b,)化学降解,(,Chemical degradation,),低分子醇、酸、水可使聚酯、聚酰胺等醇解、酸解、水解,(Polyester,polyamide etc,can be degradated by small molecule like alcohol,acid,water),:,醇解,酸解,水解,降解反应使分子量降低,在聚合和加工中都可能发生,Degradation can decrease the molecular weight,it can be happened in polymerization and manufacturing procedure、,28,29,(c),链交换反应,(Chain exchange reaction),聚酯、聚酰胺、聚硫化物得两个分子可在任何地方得酯键、酰胺键、硫键处进行链交换反应,、,Chain exchange reaction can be happened at ester,amide or sulfide linkage in anywhere of two molecules of polyester,polyamide or polysulfide、,对于链交换反应:,30,特 点,Characteristics,既不增加又不减少官能团数目,不影响反应程度,(Neither increase nor decrease the number of functional groups,on influence in degree of conversion),不影响体系中分子链得数目,使分子量分布更均一,(No influence on the number of molecule chains in the system,make molecular weight distribution to be more close to 1、0),不同聚合物进行链交换反应,可形成嵌段缩聚物,(Block condensation can be formed in chain exchange reaction between different polymers),31,2、4,线形缩聚动力学,(Kinetics of Linear Condensation Polymerization),1,)官能团等活性理论,(Equal reactivity of functional groups theory),缩聚反应在形成大分子得过程中就是逐步进行得;若每一步都有不同得速率常数,研究将无法进行;,Flory,提出了官能团等活性理论,:,不同链长得端基官能团,具有相同得反应能力和参加反应得机会,即官能团得活性与分子得大小无关。,Reactivity of functional groups is independent to the size of molecule、,32,2,)线形缩聚动力学,(Kinetics of linear condensation polymerization),a),不可逆条件下得缩聚动力学,(Kinetics of condensation in inreversible condition),羧酸和醇得酯化为可逆平衡反应,如及时排除副产物水,符合不可逆条件,且属于酸催化反应,:,33,(,2-4,),聚酯反应速率用羧基消失速率来表示:,(,2-4,),代入(,2-4,)式得:,34,聚酯反应速率用羧基消失速率来表示:,C,+,(OH),2,就是质子化羧基得浓度,难以确定,设法消去,考虑到催化剂,HA,得电离平衡:,则,代入,得,（,2-5,）,假定:,自催化反应为三级反应,(,2-6,),自催化缩聚反应,(,Self-Catalyzed Condensation Polymerization,),形成酯键得过程中,有两个羧酸分子和一个醇分子同时参与反应,因此此时反应为三级反应,即:,由反应程度,（,2-6,）,聚合度,（,2-7,）,37,自催化下聚酯得动力学方程,实验表明,当,P,0、8,时,式,27,不符合。这可能与聚合初期酸性逐步降低有关。当,P,0、8,以后,式,27,符合得较好。这时才就是真正大分子形成得过程。,(,2-7,),由上式得:,(,X,n,),2,与,t,成线性关系,即聚合度随,t,缓慢增加;,以(,X,n,),2,对,t,作图,由直线斜率可求得平衡常数,K,。,38,（,2-8,）,（,2-9,）,外加酸催化为二级反应,39,外加酸催化缩聚反应,(Added acid-catalyzed condensation polymerization),为了加速反应,常用外加酸作为聚酯化反应得催化剂,反应速率将由自催化和酸催化两项组成:,则,b),40,b),可逆条件下得缩聚动力学,(Kinetics of condensation in reversible condition),聚酯反应速率就是正、逆反应速率得差值,根据反应程度：,代入速率方程得:,和,那么，水未排出时聚酯反应速率可记为：,而水部分排出时聚酯反应速率：,因,K=K,1,/K,-1,则,K,-1,=K,1,/K,代入上面两式,得,（,2-10,）,（,2-11,）,41,若反应体系得平衡常数,K,值很大,则方程中第二项可忽略,上面两方程变为:,积分后得:,因此缩聚反应动力学为二级反应,这和不可逆外加酸催化缩聚相同。,42,43,1,)影响线性缩聚物聚合度得因素(,affected factors),反应程度对聚合度得影响,任何情况下,缩聚物得聚合度均随反应程度得增大而增大。,For condensation polymer,in any case,the degree of polymerization increased with extent of reaction、,44,2、5,影响线形缩聚物聚合度得因素和控制方法,(Factors that influence the polymerization of linear condensation polymer;Method of control),条件,等当量,不可逆,可逆反应,原料非等当量比,反应程度受到某些条件的限制,平衡常数,K,对聚合度得影响,在可逆缩聚反应中,平衡常数,K,对反应程度,p,和聚合度,Xn,有很大得影响。如果不及时除去小分子副产物,将无法提高,Xn,。,In reversible condensation polymerization,K is great influenced on P and Xn、The degree of polymerization wont be increased if pyproducts dont be removed in time、,密闭体系中,等当量官能团,小分子副产物未排出:,正、逆反应达到平衡时，总缩聚反应速率等于零，则：,so,，,（,2-12,）,45,(仅,P0.99,）时，,(,2-14,),上式近似表达了实际操作中,Xn,、,K,和,n,w,之间的定量关系,在生产中,要使,Xn 100,不同反应允许得,n,W,不同,K,值,n,W,(mol/L),聚酯,4,4 10,4,(高真空度),聚酰胺,400,4 10,2,(稍低真空度),可溶性酚醛,10,3,可在水介质中反应,小 结,2,)线性缩聚物聚合度得控制方法,-,端基封锁法,(,Method of Control),反应程度和平衡条件就是影响线性缩聚物聚合度得重要因素,但通常不能用作调控聚合度得手段。,因缩聚物得分子两端一直保留着可以继续反应得官能团,因此可以采取,端基封锁法,使大分子链失去反应活性,从而起到调控聚合度得目得。,49,端基封锁法:,在两反应官能团等当量得基础上,(,a),使某官能团稍过量,(b),加入少量单官能团得物质,End blocking:,one of functional groups is a little excess or add a small quantity of monofunctional chemicals、,分三种情况进行讨论:,单体,aAa,和,bBb,反应,让,bBb,稍过量,、,单体,aAa,和,bBb,官能团等当量,外加少量得单官能度物质,C,b、,单体,aAb,体系中加少量得,C,b,、,50,单体,aAa,和,bBb,反应,让,bBb,稍过量,设,N,a,、,N,b,分别为官能团,a,和,b,得起始数,则两单体得官能团数之比为:,(,2-15,),r,称为,摩尔系数,理论分析时常用,r,。,用,bBb,单体得,分子过量分率,q,即:,（,2-16,）,51,r-q,关系式,r,(或,q,)与聚合度,Xn,、反应程度,p,有啥样得关系呢？,设,a,得反应程度为,p,则:,a,得反应数为,N,a,p,(,也即为,b,官能团得反应数);,a,得残留数为,N,a,-N,a,p,;,b,得残留数为,N,b,-N,a,p,;,a,、,b,得残留总数为,N,a,+,N,b,-2N,a,p,;,所以体系中大分子得数量总就是残留官能团得一半,即大分子个数应为(,N,a,+,N,b,-2N,a,p,),/2,。,52,体系中所含得结构单元数应为所有参加反应得单体数,也即为官能团总体数量得一半(,N,a,+,N,b,),/2,。,由,得:,(,2-17,),上式表示了聚合度,Xn,与反应程度,P,、摩尔系数,r,或过量分率,q,之间得定量关系,53,两单体完全等当量,即,r=1,或,q=0,则:,反应程度,p=1,时,即,a,反应完全,则:,讨论两种极限情况:,(,2-18,),(,2-19,),54,单体,aAa,和,bBb,官能团等当量,外加少量得单官能度物质,C,b、,体系中,a,和,b,相等,都记为,N,a,设,N,c,为,C,b,得官能团数,则:,此反应体系中,因,aAa,和,bBb,官能团等当量,因此可认为,a,得残留数和,bBb,中,b,得残留数相等,即为,N,a,-,N,a,p,两单体官能团残留总数为,2,(,N,a,-,N,a,p,)。,55,结构单元数(等于单体数量),即,N,a,+,N,c,(,2-20,),56,体系中大分子总数,单体,aAb,体系中加少量得,C,b,、,57,58,