Preparation Of Micro/nano-particles Based On PGMA Block Copolymer

Micro/nano-particles have been widely used in many fields such as adsorption /separation,catalyst supporting,ion exchange,sensors,biomedicine etc,due to their high specific surface area,low density and strong adsorption capability.As a functional monomer owning epoxy group,glyidyl methacrylate(GMA)can undergo many chemical reactions,therefore provides PGMA with the multiple modification possibility for functional materials.Herein,porous microspheres and self-assemblies with multiple morphologies were prepared via RAFT solution polymerization followed by emulsion process and RAFT dispersion polymerization induced self-assembly(PISA)respectively.Poly(2-hydroxypropyl methacrylate)-b-poly(glycidyl methacrylate)(PHPMA-b-PGMA)with three different block composition was prepared by RAFT solution polymerization.Oil in water emulsion(O/W)was prepared through various emulsification process such as magnetic stirring(M),homogenization(H),membrane jet-flow(SPG),and combination of which via adding solution of PHPMA-b-PGMA in dichloromethane(DCM)into the aqueous solution containing emulsifier.Porous microspheres were obtained after the evaporation of DCM.It was found that the microspheres with the best size regularity and porosity were obtained from sodium dodecyl sulfate(SDS)solution with 1 critical micellization concentration(CMC)by H&M process.Within a certain range,the number of pores on the surface of the microspheres increases with the increasing in SDS,but the particle size is getting smaller.Microspheres with uniform size but no pores could be prepared using cetyltriethylammnonium bromide(CTAB)as emulsifier,whereas non stable emulsion was obtained when polyoxyethyleneoctylphenyl-10(OP-10)was used as emulsifier even its concentration up to 100 CMC.Self-assemblies of Poly(oligo(ethylene glycol)methyl ether methacrylate)-bpoly(glycidyl methacrylate)(POEGMA-b-PGMA)with multiple morphologies were prepared via RAFT dispersion polymerization of GMA mediated by POEGMA macro chain transfer agent(CTA)in ethanol through PISA process.Spherical(<50 nm),worm-like(50 nm),vesicular(100-300 nm)morphology were observed consecutively when the block length of PGMA increased,indicating good controllability in morphologies.The linearly increase of molecular weight and narrow distribution remaining during the polymerization revealed the good living characteristic.Aggregates after cross-linking catalyzed by triethylamine showed good solvent resistance in THF and DMF,indicating the potential in crosslinking and post-modification of obtained assemblies.The morphology of assemblies changes greatly with the incorporation of certain mass ratio of tert-butyl methacrylate(TBMA)in the second block to form POEGMA-b-P(GMA-co-TBMA)block copolymer.The self-assemblies of AC/ABC diblock-triblock blends were prepared by RAFT dispersion polymerization of styrene mediated by mixed POEGMA-macro-CTA and POEGMA-b-PGMA-macro-CTA in ethanol.With the increase of block length of polystyrene,the nanowires and vesicles,vesicles,microspheres can be consecutively obtained.The post modification and gold loading experiment showed that the PGMA was unevenly distributed in assemblies with different morphology and multi-compartment vesicles were obtained.