Preparation Of Large-size Ag Nanoparticles In Spherical Polymer Brushes And Hydrogel Structure

Ethylene oxide, as important as polyethylene and polyvinyl chloride, is significantly an important ethylene-based derivative in chemical industry, where lots of common-used chemical products are made from it, such as ethanediol and diethylene glycol. Since Ag catalysts play an important role in synthesizing the ethylene oxide where this kind of catalyst is easy to be fragile and unrecyclable, therefore, it is essential to find an appropriate system where Ag catalyst can be properly immobilized.The micro-gel system is much advantageous against some other counterparts, due to its stability, easy to synthesize, good control of particle-embedded size and easy response-stimulus behavior. The micro-gel system is much advantageous against some other counterparts, due to its stability, easy to synthesize, good control of particle-embedded size and easy response-stimulus behavior. Nano-sized metallic particles embedded onto the micro-gel are cut-the-edge new types of catalysts consisting of all the merits of homogeneous and pseudo-homogeneous catalysts, such as high catalytic activity and easy to separate and reuse. And spherical polyelectrolyte brush (SPB) is also a promising carrier system with the ability to embed metallic nano-particles and the stability, just like the micro-gel. Hydro-gel system has, however, net structure cross-linked. As a result, large-sized metallic particles are hypothetically supposed to be netted by this system.This study focused on the optimal synthesis of systems of SPB and microgel in which there are PB core and PAA and PNIPA chains respectively. By adopting the several-round-precursor-adding solution, larger diameter of Ag particles have been successfully synthesized to be used as catalyst for getting ethylene oxide.Through synthesizing, immobilizing and characterizing Ag particles in the systems of SPB and microgel systems, the main work here includes:Using industrial product PB as core, KPS as thermo-initiator, PNIPA as monomer to synthesize PB-PNIPA SPB with the technique of thermo-sensitive emulsion polymerization. When the temperature reaches70℃, as well as reaction time90minutes, PNIPA monomer75wt%, the synthesizing gets the optimal result in terms of disperstiveness and stability. By the technique of DLS, the diameter is nearly652nm. Loading the Ag particles onto the system of PB-PNIPA SPB through the in-situ restoration technique, nearly20nm diameter particles can be synthesized. And with different monomer used in the system, the diameter of Ag particles is changing.1. The nanoreactor containing PB core and PAA chain is suitable for the immobilization of Ag particles. With different monomer rate of PAA used in this synthesis, different, but increasing diameter of Ag particles immobilized onto this system have been synthesized through the technique of several-round-precursor-adding solution.2. The PB-PNIPA-BIS microgel system has been synthesized by thermo-emulsion polymerization with different BIS, crosslinker, content. It is clear that with the increasing BIS content used in this system, the diameter of Ag particles is going down. And when using the technique of several-round-precursor-adding solution, the diameter of Ag particles is becoming larger.3. Hydrogel system, with PNIPA as monomer and BIS as crosslinker, has network structures, which can contribute to the immobilization of Ag particles. With decreasing BIS content used into the system, the diameter of Ag particles is enlarged indirectly proved by the catalyzing ability test. And using the technique of several-round-precursor-adding solution, after three times loadings, the diameter of Ag particles is enlarged proved by the catalyzing ability test.