Preparation And Functionalization Of Micro/nano Particles Of Active Methacrylate Block Copolymer

Micro/nano particles have a wide range of potential applications in many fields such as adsorption separation,catalyst load,particle exchange and biomedicine,etc,due to their advantages such as high specific surface area,low density and high adsorption capacity.Polymers from reactive methacrylates have been widely studied and applied because of the capability of the functionalization of reactive groups,such as carboxyl group,hydroxyl group,amine group?primary,secondary and tertiary?,epoxy group,tert-butyl easter etc.For instance,ring-open reaction of epoxy group with molecules owning reactive protons resulted cross-linking or post-modification of poly glycidyl methacrylate?PGMA?;hydrolysis of tert-butyl ester groups of poly tert-butyl methacrylate?PTBMA?transfer it to hydrophilic,pH sensitive poly carboxylic acid;hydroxyl group in poly hydroxypropyl methacrylate?PHPMA?endow it weak hydrophilicity and good biocompatibility.Herein,the preparation of porous microspheres and self-assemblies of block copolymers composed of PGMA and PHPMA via double emulsion method and RAFT dispersion polymerization induced self-assembly?PISA?,respectively were studied.PHPMA-b-PGMA with three different block ratios synthesized by RAFT solution polymerization were applied to prepared porous microspheres via double emulsion method.W₁/O emulsion form ultrasonic emulsification of small amount of water in the PHPMA-b-PGMA solution in DCM was dispersed in water containing various of sodium dodecyl sulfate?SDS?via stirring to form a W₁/O/W₂ double-emulsion.Porous microspheres were obtained after the evaporation of DCM.Optical observation of microspheres during evaporation was used to investigate the pores formation mechanism.It is found that the pore structure of microspheres can be tuned via adjusting the concentration of SDS,the composition and concentration of block copolymers.It is found that higher SDS concentration resulted more open pores on the surface as well as smaller size of the microspheres when other factors fixed.Similarly,larger PHPMA ratio resulted in more open porous structure as well as smaller particle size.The cross-linking of porous microspheres significantly enhance their solvent durability.The open porous structure of cross-linked microspheres closed after solvent vapor swelling,which probably find its application in guest embedding.Self-assemblies with various morphologies were obtained via RAFT dispersion polymerization of GMA mediated by PHPMA macro chain transfer agent in the ethanol.It is found that the system has good controllability both on the morphology of assemblies and molecular weight of polymers,with consecutively obtaining of spherical,cylindrical and vesicular morphology with the PGMA block increases and linearly increases of molecular weight with conversion increases.Both dispersion copolymerization of GMA and TBMA mediated by PHPMA macro-CTA and chain extension using PHPMA-b-PGMA vesicles as seeds for dispersion polymerization were carried out to investigate the effect of incorporation of TBMA unit and PTBMA block on the morphology transformation.Interestingly,PTBMA block extended in PHPMA-b-PGMA vesicles gradually degenerate the vesicular morphology to nanowires and irregular nano-particles when the chain length of PTBMA increases.Similarly,TBMA units incorporated into the second block were also degenerate the vesicular morphology of self-assemblies of BCPs containing pure PGMA block to nanowires and irregular nano-particles as the fraction of TBMA increases.