The Synthesis Of Amphiphilic Connetworks By Reversible Addition-Fragmentation Chain Transfer(RAFT) Polymerization

Amphiphilic conetwork(APCN)is two-component networks of covalently interconnected hydro-hilic/hydrophobic(HI/HO)phases with co-continuous morphology;as such they swell both in water and hydrocarbons,and respond to changes in the medium by morphological isomerization.Because of its unique structure and property,it is widely used in biomedical fields,such as contact lenses,controlled drug delivery systems,artificial pancreas and so on.APCN consists of poly N-Viny Pyrrolidone(PVP)or poly N,N-dimethyl acrylamide(PDMAAm)and PDMS segments attracts most researchers’ attention.Mainly because PVP and PDMAAm have good resistance to hydrolysis and good biocompatibility,and PDMS has high oxygen permeability,which is important to biological materials.RAFT polymerization can well control the molecular weight and molecular weight distribution of the resulting polymer,which provides a possible way to prepare APCN with more uniformity in size.In this article,two kinds of functional trithiocarbonate were synthesized as RAFT agents.Homopolymer PVP and allyl functionalized telechelic PS-DMAAm-PS was synthesized by RAFT polymerization under different conditions and their effects on the molecular and molecular distribution were also discussed.The well defined allyl-functionalized telechelic PS-PDMAA-PS reacted with vinyl-terminated PDMS with Pt as catalyst,to synthesize a new linear random multiblock copolymer PDMAA-PDMS contained SiOEt groups,which was further cross-linked to APCN,and the swelling property was test.The main research is described as followed:(1)Synthesis of functional RAFT agent:S,S’-Bis(α,α’-dimethyl-α"-acetic acid)-trithioca rbonate(BDATC)and S,S’-bisallyl trithiocarbonate(BATTC)was synthesized by phase-tra nsfer catalyzed reaction and anion resin exchange method respectively.The structure was c onfirmed by FT-IR and NMR spectra.(2)RAFT polymerization of NVP with BDATC as chain transfer agent and terminate d modification:The effect of reaction temperature,time and feed ration on the polymerizat ion was discussed.The polymer obtained was reacted with unsaturated alcohol by esterific ation.The result indicated that the molecular weight increased with conversion linearly wh ich was agreed with control polymerization.However,the esterification reaction was unsuc cessfully mainly because of large molecular of the polymer.(3)RAFT polymerization of DMAAm with BATTC as chain transfer agent:Macro PS-CTA was synthesized via the bulk RAFT polymerization at 110℃.Allyl functionalized telechelic PS-DMAAm-PS was synthesized by the RAFT polymerization of DMAAm was with PS-CTA as RAFT agent.The effect of reaction temperature,time and solvent on the polymerization was discussed.The result showed that the molecular distribution was well controlled.(4)Synthesis of multiblock copolymer and APCN:The well defined allyl-functionali zed telechelic PS-PDMAA-PS was reacted with allyl-terminated PDMS under Pt catalyst to synthesize a new linear random multiblock copolymer PDMAA-PDMS contained SiOEt gr oups,which was further cross-linked to APCN.The swelling degree of APCN in water was 200%and is expected to be used as a cell encapsulation material.