Preparation And Properties Of Organic/Inorganic Hybrid Material Via RAFT Polymerization

Radical polymerization is very important in industry production because it is suit to various monomers and its reaction condition is moderal. About 70% plastic come from radical polymerization. However, the traditional radical polymerization to graft the polymer chains from the substrates is difficult to control the molecular weight, molecular weight distribution as well as architectures because its slow initiation, rapid increasing and the quick terminate characteristic etc, which bring the interest of the academe and the industry of polymer in " living" polymerization. In 1998, Rizzardo reported their pioneering work RAFT polymerization. The appearance of RAFT "living" polymerization technique conquers these limitations by introducing the suitable addition-fragmentation chain transfer agents [such as S=C (Z) S-R] to the polymerization system. The system involve a reversible chain transfer in which a dithioester behaves as a transfer agent reacting with initiating and propagating radicals to give a transfer agent and a species that is able to initiate polymerization. The dithioester is transferred between the active and dormant chains, thus maintaining the living character of the polymerization.In 1984, Schmidt etc bring forward the conception of organic/ inorganic hybrid material firstly. Organic/ inorganic hybrid material is a kind of even and multiphase material. It have become a focus of material science study because it integrate the excellence of organic and inorganic material. Polymer nanocomposites prepared by using layered materials are expected to lead to a high degree of polymer ordering and exhibit advanced gas barrier, thermal stability and enhanced mechanical properties compared to pristine polymers. In recent years, this study has become a foreland field of polymer chemistry and physics, physical chemistry and material science etc and take attention of the scientist in various country.Four aspects are studied in this paper: polymers were grafted to the inorganic particles surface using different inorganic particles carried different CTAs as CTAs; Block copolymers were grafted to the inorganic particles surface using different inorganic particles carried azo-initiator as initiator with CTA exist; Random copolymers were grafted to the inorganic particles surface with the functional ethylene introduced onto the inorganic particles surface and CTA existed; Intercalative organic/ inorganic hybrid materials were prepared under the samdwich silicate and CTA exist. The microstructures, thermal characteristics, the organic content, the molecular weight and the molecular weight distribution of the material were characterized and measured with FT-IR, NMR, SPM, TG, GPC etc. respectively. As a whole, the complex materials prepared by this four methods own contolled molecular weight, architectures were and excellent thermal stability.The main study results as follows:一,RAFT polymerization using functional inorganic particles as CTA1. Si-g- PMMA polymer brushes prepared via RAFT process using modified silicon wafer as a RAFT agent are well investigated. The data obtained indicates that the PMMA are grafted on the silicon surface. The GPC analysis reveals that the Mn of the grafted polymer approximately increases linearly with increasing monomer conversion, and the polydipersity ranges (Mw/Mn) from 1.36 to 1.41.2. This study reports a method to prepare new controlled molecular weight and low polydispity organic/"inorganic" hybrid. The XPS and FT-IR analysis indicate that the RAFT agent have been introduced onto the palygorskite surface and the PMMA have been "grafted from" the modified palygorskite. The GPC results show the RAFT polymerization is a controlled/"living" polymerization. SPM and TGA results show the organic content of the materials is high.3. The ethyl xanthate groups have been successfully introduced to the surface of silica and silica gel. PMMA chain has grafted from the surface by RAFT polymerization using ethyl xanthate groups immobilized on silica and silica gel as surface chain transfer agent. The molecular weights, molecular weight distribution and surface properties are measured by GPC and SPM measurements. The GPC results reveal that the polymerization is a controlled process with a "living" characteristic. The SPM images show that the polymers grafted from silica and silica gel surface is uniform. The thickness of PMMA layer reaches about 34.02 nm and 33.76 nm under the RAFT polymerization condition.4. A new type of organic/inorganic nano hybrid material are prepared though RAFT polymerization of MMA using the ethyl xanthate-terminated bentonite as CTA. FT-IR and SPM results indicate that the MMA have grafted to the bentonite surface. TG datas show the thermal stability is well, organic content of the materials is increasing with the reaction time increased which can reach 12.7 % at most. The GPC results reveal the molecular weight distribution is narrow, the Mn of the grafted polymer approximately increases linearly with increasing monomer conversion. The linear first order kinetic plot indicated that the radical concentration was constant throughout the polymerization.These studies are not found in any other articles of the world at present.二,The study of inorganic particles suface initiat monomer block copolymerization via RAFT.1. Halloysite suface initiated RAFT radical polymerzaion is studied at first. The results show the polymerization is a controlled/"living" polymerization. The Mn of the grafted polymer approximately increases linearly with increasing monomer conversion and the kinetic plot is in first order. The hybrid marerial can initiate other monomer polymerization again and then block copolymer/inorganic complexes were synthesized. TG data show the materials have excellent thermal stability.2. A kind of organic/inorganic nano hybrid material are prepared though RAFT polymerization of MMA using nano-silicon carried azo-initiator as initiator in ionic liquid. The hybrid marerial can initiate styrene monomer polymerization again. The FT-IR, ~1HNMR and elemental analysis results indicate that the ionic liquid have been successfully synthesized; SPM show that the PMMA have grafted on nano silicon surface. GPC result reveal that the molecular weight distribution is narrow, the Mn of the grafted polymer approximately increases linearly with increasing monomer conversion and the kinetic plot is in first order. The RAFT polymerization is a controlled/"living" polymerization.三,Preparation and properties of random copolymer/inorganic nano hybrid material via RAFT.1. MAn and St are copolymeried on silicon surface with the functional ethylene introduced onto the silicon particles surface and TNPBE existed is reported at first here. The results show the PMAn/PS/SiO2 have been preparaed successfully. The polymerization process are carried out according to RAFT mechanism. The materials' thermal stability increased because of the introduce of SiO2.2. St and An are copolymeried using AIBN as initiator, TNPBE as CTA and the OMMT exist. The polymerization show a "living" radical polymerization characteristic. The terminal of the polymer chains have CTA segment according to the structure analysis of the material. PS/PAn copolymer have Intercalated into the layers of MMT. TG results show the material have excellent thermal stability.