Research On Preparation Of Porous Carbons From Vinylidene Chloride-based Block Copolymers

Vinylidene chloride(VDC)based polymers have the advantages of resistance to chemical corrosion,transparency and good barrier property,Polymerization mechanism of VDC based polymers in industrial production are all traditional free radical polymerization.The characterized of free radical polymerization is slow initiation,fast propagation,rapid termination and easy transfer,thus causing the regularity of the polymer poor,abnormal molecular chain structure,broad molecular weight distribution.Due to high chain transfer constant of VDC monomer,now living free radical polymerization method only is reversible addition-fragmentation transfer(RAFT)to adapt to living radical polymerization of VDC monomer,but RAFT reagent limits the use of RAFT method.In this paper,single electron transfer living radical polymerization(SET-LRP)on VDC-MA copolymer were conducted by using CHI3 as the initiator,Na2S2O4 /NaHCO3 as the catalyst system,hydroxypropyl methyl cellulose and methyl cellulose as dispersant.The effect of reaction time,reaction temperature,dosage of initiator,dosage of catalyst for VDC-MA polymerization were investigated.The experiments results showed that the polymerization conversion rate increased with the increase of reaction time,the conversion increased slowly in the late,ln([M]0/[M]t)had primary linear relationship with the reaction time;With the increase of reaction time,the conversion and the molecular weight increased,molecular weight distribution got narrow,reaction had the general characteristics of active polymerization.Proper polymerization condition was the ratio of the reactants n(VDC):n(MA):n(Na2S2O4): n(NaHCO3)=400:50:6.14:18,reaction temperature 45 ℃,reaction time of 18 h,CHI3 and VDC monomer mass ratio of 0.005:1.Structure of the VDC-MA copolymer were determined by FTIR and 1H-NMR.Speculated mechanism showed that the polymerization method was in line with the single electron transfer living free radical polymerization characteristics.The porous carbon was by direct carbonization of VDC-MA copolymer.With the increase of MA in copolymer,the thermo-gravimetric features of copolymer showed that carbonized surplus weight rate decreased,it was stated that the introduction of MA could change the pore structure.The carbonized materials were investigated by XRD,pore structure and specific surface area,apparent morphology and TEM.The obtained porous carbons from VDC-MA copolymer of different proportion stripping exhibited IV type absorption behavior with hysteresis loops.VDC-MA20 copolymer-based carbon obtained specific surface area of 968 m2·g-1,the hole rate of 45.6%.MA decomposition in VDC copolymer can be formed mesoporous and even macroporous.