VDF/CTFE共聚物原子转移自由基反应法氢化制备VDF/TrFE/CTFE三元共聚物的研究

ATOM TRANSFER RADICAL REACTION METHOD PREPARING VDF/TrFE/CTFE TERPOLYMER BY REDUCTIVE DECHLORINATION OF VDF/CTFE COPOLYMER

报道了一种用于偏氟乙烯-三氟氯乙烯共聚物(VDF/CTFE共聚物)制备偏氟乙烯/三氟乙烯/三氟氯乙烯共聚物(VDF/TrFE/CTFE共聚物)的新方法,该方法以CuCl与2′,2-Bpy的配合物为催化剂,N-甲基吡咯烷酮(NMP)为溶剂,异丙苯(丙酮、2,6-二叔丁基-4-甲基苯酚)为链转移剂,通过原子转移法在VDF/CTFE共聚物上产生自由基,进而利用自由基链转移反应将VDF/CTFE共聚物上部分Cl原子用H原子取代以制备VDF/TrFE/CTFE三元共聚物.对该体系的反应机理及其影响因素进行研究发现,随着实验温度的升高(80～140℃),反应时间的延长,氢化量增加,产物中TrFE含量增加;反应温度越高,初始反应速度越快,完全氢化时间越短;催化剂与氢化量的比例基本为1:1,通过控制催化剂的量可以定量控制氢化率;新的反应体系不会对产物的分子量产生大的影响.

A novel catalytic hydrogenation method of dechlorination for P（VDF-co-CTFE）s to convert CTFE units into TrFE units through CuCl/2,2＇-bipyridine catalyzed atom transfer radical reaction and chain transfer reaction was reported in this work.In this method,the Cl atom in VDF/CTFE copolymer has been first removed by CuCl/2,2＇-bipyridine complex via reductive reaction,and P（VDF-co-CTFE） macromolecule free radicals has been generated.In the presence of chain transfer agent,the free radicals would grab an H atom and the polymer radical is terminated.As a result,Cl atom has been exchanged with H atom,and P（VDF-co-CTFE） is transferred into P（VDF-co-TrFE-co-CTFE） or P（VDF-co-TrFE） as desired.The effect of solvent,reaction temperature,reaction time and catalyst dosage on the hydrogenation of P（VDF-co-CTFE） has been well discussed.It has shown that a certain reaction temperature is required to activate the reaction,and high temperature favors the reaction rate.As reaction time prolongs,the hydrogenation ratio of CTFE units increases until they are fully converted or either the catalysts or the chain transfer agents run out.The amount of TrFE units could be exactly controlled by introducing the catalyst in desired dosage since one initiator molecule is only able to hydrogenate one CTFE molecule.The rather close limiting viscosity number of P（VDF-co-CTFE） and the resultant P（VDF-co-TrFE-co-CTFE） means that no decomposition or coupling reaction happens in the process.Generally,the new method possesses advantages such as lower cost,lower toxic,higher convenience and higher controllability compared with the previous method.