Studies And Applications Of Atom Transfer Radical Polymerization Based On Microliter Volumes

Designing polymer materials with novel and controlled structures have become a hot topic via development of new technologies to regulate polymerization reactions and metal-free catalytic systems in recent years.In this thesis,we summarized the methods of preparing polymer brushes by externally stimulated polymerization,and the progress of preparation of gold/polymer nanocomposites as well as their applications in the simulation of peroxidase catalysis.From which the research ideas of the present work are derived.First of all,microfluidically mediated atom transfer radical polymerization was developed;Secondly,the metal-free catalyst was synthesized,further,the influence of atom transfer radical polymerization based on microsolution on the preparation of polymer brushes was investigated;Finally,polymer brushes with special activated groups on the surface were obtained by means of trace solution,at the same time,gold nanoparticles with uniform size and distribution were obtained by using the gold nanoparticles as templates.Based on this,the catalytic performance of gold/polymer nanocomposites in simulating peroxidase activity was studied.The main contents and conclusions are listed in the following:(1)In this work,surfaces with a controlled gradient of polymer brushes were fabricated via microfluidically mediated atom-transfer radical polymerization(ATRP).This methodology used a sealed sandwiched setup with a parallel alignment of the initiator-substrate with the metal substrate.A syringe-pump injected small volumes of Cu(I)/Bipy₂activator/monomer solution directly into the bottom of the setup while ATRP at the frontal initiator-substrate was simultaneously initiated.The trace amount of injection solution locally confined polymerization to occur only on areas in contact with the solution which resulted in the spontaneous formation of gradient structures.A surface-attached polymer gradient was regulated via either the solution injection rate or monomer/catalysis concentration,thereby yielding a controllable gradient with uniformly grafted polymers of potassium 3-sulfopropyl methacrylate could be achieved on the same substrate.(2)The metal-free catalyst N-phenylphenothiazine(PTH)was synthesized and alkyl bromine initiator was modified on the silicon wafer surface.The fabrication of well-defined,multifunctional polymer brushes under ambient conditions was described in this work.This facile method uses light-mediated,metal-free atom transfer radical polymerization(ATRP)to grow methyl methacrylate(MMA)monomer was successfully grafted on the surface of silicon wafer by using microliter volume solution.Simultaneously,polymer brushes with different thickness were prepared by changing the light time and catalyst concentration with only microliter volumes required of this novel strategy.Key to the success of this strategy was the dual action of N-phenylphenothiazine(PTH)as both an oxygen scavenger and polymerization catalyst.It was preliminarily concluded that visible light irradiation of a trace solution containing N-phenylphenothiazine could induce the polymerization of methyl methacrylate under environmental conditions.(3)The methacryloyl ethyl trimethyl ammonium chloride(MEATC)brush with special active groups on the surface of a single-crystal silicon wafer was fabricated via atom transfer radical polymerization(ATRP).Au nanoparticles with high dispersion and narrow particle size distribution were obtained using the brush as template Further,a simple flow catalytic device was designed using a polymethylacrylamide ethyl trimethylammonium chloride brush loaded with gold nanoparticles as template,with2,2-diazo-bis(3-ethylbenzothiazol-6-sulfonic acid)ammonium salt(ABTS)as the chromogenic substrate.Preliminarily,the catalytic performance of gold/polymethylacrylamide ethyl trimethylammonium chloride brush composite in simulating peroxidase activity was studied.