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.