Preparation Of Monodisperse "Living" Polymer Microsphere And Its Application On Molecularly Imprinted Technology

As an excellent new functional material, monodisperse functional polymer microspheres could be used in many fields such as HPLC, solid phase extraction and molecularly imprinted technology. The aim of this thesis is to prepare monodisperse, highly cross-linked, surface-functionalized and "living" polymer microspheres with uniformly cross-linked structures by atom transfer radical precipitation polymerization (ATRPP). The "living" polymer microspheres were also could be obtained via ATRPP at ambient temperature with the rational use of harmfulless polar alcoholic solvents. Molecularly imprinted polymer with homogeneous binding sites and enzyme inhibition potency could be prepared on the surface of the polymer microsphere by the controlled surface imprinting approach. The dissertation presents the following main points:1. The simple introduction of atom transfer radical polymerization (ATRP) mechanism into precipitation polymerization system allows the direct generation of uniformly cross-linked "living" polymer microspheres. A facile, general, and efficient one-pot approach to obtaining monodisperse, highly cross-linked, surface-functionalized, and "living" polymer microspheres with uniformly cross-linked structures by atom transfer radical precipitation polymerization (ATRPP) is described. The polymerization parameters (including stirring rate, monomer loading, initiator and catalyst concentrations, and molar ratio of cross-linker to monovinyl functional comonomer, and polymerization scale and time) had proven to show significant influence on the morphologies of the resulting polymer microspheres, which made it very convenient to control the particle sizes by easily tuning the reaction conditions. The general applicability of ATRPP was demonstrated by synthesizing a series of uniform functional copolymer microspheres with different incorporated functional comonomers (i.e,4-vinylpyridine, acrylamide, and2-hydroxyethyl methacrylate). Moreover, the "livingness" of the resulting polymer microspheres was confirmed by their direct grafting of hydrophilic polymer brushes via surface-initiated ATRP under mild reaction conditions.Furthermore, a "grafting from" particle growth mechanism was proposed for ATRPP, which was considerably different from the "grafting to" particle growth mechanism in the traditional precipitation polymerization.2. The simple introduction of alcoholic solvents into atom transfer radical polymerization precipitation polymerization (ATRPP) system allows one-pot synthesis of monodisperse, highly cross-linked, surface-functionalized and "living" polymer microspheres. The polymerization parameters (including the monomer loading, polymerization time and different kinds of solvents) proved to have a pronounced influence on the yields and morphologies of the polymer microspheres, which made it very convenient to tailor the particle sizes by tuning the polymerization conditions. The general applicability of ambient temperature ATRPP was demonstrated by its successful application in a range of alcoholic solvents as well as its versatility in the synthesis of a series of uniform copolymer microspheres of different monovinyl functional monomers (i.e,4-vinylpyridine, glycidyl methacrylate, methyl methacrylate, and2-hydroxyethyl methacrylate) with cross-linker. In addition, the "livingness" of the resulting polymer microspheres was confirmed by their direct grafting of hydrophilic polymer brushes via surface-initiated ambient temperature ATRP, leading to advanced functional polymer microspheres with significantly improved surface hydrophilicity.3. A facile, general, and highly efficient approach to prepare uniform core-shell molecularly imprinted polymer (MIP) particles with enzyme inhibition potency is described for the first time, which involves the combined use of molecular imprinting technology and controlled/"living" radical polymerization (CRPs) techniques as well as stoichiometric non-covalent molecular imprinting strategy. The enzyme imprinted surface layers of the core-shell MIP microspheres were prepared by tuning the polymerization parameters (including the monomer loading and polymerization time). The thickness and composition of the enzyme imprinted surface layers of the core-shell MIP microspheres were characterized with SEM, FT-IR, elemental analysis and dynamic light scattering. The absorption performance and inhibition potency towards the enzyme were also studied. The thickness of the enzyme imprinted surface layers of the core-shell MIP microspheres had a significant influence on their binding properties and only those with their thickness comparable with the diameters of the targeted enzymes could afford enzyme-MIPs with optimal specific bindings. The as-prepared enzyme-MIPs were found to have homogeneous binding sites via Langmuir simulation, high binding capacities, rapid affinity and high selectivity towards template. They proved to show much higher enzyme inhibition potency than the small inhibitor by3orders of magnitude (i.e., the enzyme inhibition constant of every binding site of the MIP microspheres was about one-thousandth of that of the small inhibitor), mainly due to the formation of strong long-range secondary interactions between enzymes and imprinted pockets.