Photosynthesis Of Monodisperse Surface-functional Polymeric Microspheres

Surface-functional polymeric microspheres have been widely used in protein identifications, molecular imprinting, antifungal, preferential adsorption, environmental responsive, catalytic, and drug delivery. Using macromolecular chain transfer agent (macro-CTA) as the stabilizer is an attractive strategy to prepare surface-functional polymeric particles. However, most literatures are focused on the preparation of diblock copolymer nano-objects, while very few are focused on the preparation of uniform polymeric microspheres. Photoinitiated RAFT dispersion polymerization is an efficient methodto prepare uniform polymeric microspheres using macro-RAFT agent as the stabilizer. The main contributions of this dissertation as follows:(1) Highly monodisperse multifunctional poly(methyl methacrylate) (PMMA) microspheres were prepared by photoinitiated RAFT dispersion polymerization in an ethanol/water medium using a ketone-functional macro-RAFT agent as the stabilizer. The macro-RAFT agent was synthesized by RAFT polymerization of 2-(acetoacetoxy)ethyl methacrylate (AAEM) and poly(ethylene glycol) acrylate (PEGA). The effects of stabilizer concentration, ethanol/water weight ratio, MMA concentration, photoinitiator concentration on photoinitiated RAFT dispersion polymerization were investigated in detail. The kinetic of photoinitiated RAFT dispersion polymerization were also studied. Ag/PMMA nano-composite microspheres was prepared based on complexation reaction of silver ion with acetoacetyl groups on surface of the functional microspheres. Experimental results showed that Ag/PMMA nano-composite microspheres exhibited catalytic performance.(2) Highly monodisperse poly(2-hydroxyethyl acrylate)-grafted PMMA microspheres were prepared by photoinitiated dispersion polymerization in ethanol/water mixtures at room temperature. Three macro-RAFT agents with different molecular weights were synthesized and employed as steric stabilizers in photoinitiated dispersion polymerization. The effect of reaction conditions on particle diameter was investigated. Kinetic study indicated that the polymerization proceeded rapidly with 96% yield being reached with 1 h of UV irradiation. Finally, the obtained hydroxyl-rich PMMA microspheres were used as building blocks for the preparation of covalently cross-linked colloidosomes.(3) Poly(glycerol monomethacrylate) (PGMMA) grafted PMMA microspheres were synthesized by photoinitiated RAFT dispersion polymerization using a PGMMA macro-RAFT agent. Fe3O4 nanoparticles can be stabilized immobilization which interactions with the 1,2-diol groups of the PGMMA brushes. A certain amount of Fe3O4nanoparticleson microspheres was confirmed by SEM and TGA. The obtained magnetic microspheres were then employed for the stabilization of oil-in-water emulsion.