The Research Of Atom Transfer Radical Addition And The Immobilized Catalyst

The polychloroalkanes is one kind of very important initiator of atom transfer radical polymerization (ATRP). They can initiate many kinds of monomers to synthesize different kinds of architectures via single-step or multistep reaction, such as block, graft, star and hyperbranched Copolymers and so on. If the functionality of the polychloroalkanes in polymerization could be determined clearly, it woulde be important for the design of macromolecular structure. On the other hand, transition metal complex have been widely used because of their good catalytic efficiency for the atom transfer radical addition (ATRA) and ATRP, but the postpurification of the product is difficult. Supporting catalyst on insoluble particles is a possible solution to this problem. Catalysts immobilized on insoluble particles by physics or chemistry method can be easily separated from the reaction mixture and be recycled and reused.Three part of research works had been carried out in the dissertation. The first part: a kind of multidentate amine modified silica gel was synthesized through the following steps: (1) introduce the amino groups onto the surface of silica-gel by the treatment of surface silanol groups withγ-aminopropyl trimethoxy silane (γ-APS); (2) michael addition of excess trihydroxymethyl propyl triacrylate (TMPTA) to amino groups on the silica gel surface; (3) amidation of the unreacted double bonds of TMPTA on the surface of TMPTA modified silica gel with diethylenetriamine (DETA); (4) the multidentate amine modified silica gel was finally obtained by the reaction of amino groups on the surface of DETA modified silica gel with double bond of butyl acrylate (BA). Their chemical structures were confirmed by C¹³ NMR, infrared spectrum (FTIR) and the nitrogen content in the particles was determined by elemental analysis (EA). Then, the multidentate amine immobilized on silica gel was used as ligand for CuCl in ATRA of CCl₄ with MMA and methyl trichloroacetate with St repeatly. The conversion and purity of the product were determined through the gas chromatography and ¹H NMR respectively. Finally, the multidentate amine immobilized on silica gel was used as ligand for CuCl in ATRP of St initiated by TCPP and MMA initiated by MMTCB. The number average molecular weights of the polymers were determined through GPC. The results indicated that the multidentate amine modified silica gel ligand was synthesized successfully and the nitrogen content of this ligand is 2.5mmol/g. The multidentate amine modified silica gel is good catalytic ligand of ATRA reaction. This kind of ligand have been used seven times in the ATRA reaction of carbon tetrachloride with MMA and the methyl trichloroacetate with St, and the conversion for the first time reached above 80% in 40 hours, when the seventh time still exceeded 25%. But the multidentate amine modified silica gel ligand can not control ATRP reaction well. The second part: a kind of multidentate amine modified magnetic microspheres was synthesized through the following steps: (1) Fe₃O₄ magnetic nanoparticles were synthesized by the chemical co-precipitation and modified by oleic acid and sodium dodecyl sulfonate bilayer surfactants. The stability of the magnetic fluid is very good and can be dispersed well in polarity solvent. (2) The magnetic fluid was as seed and carried on the crossing linking copolymerization of methyl methacrylate(MMA) and trihydroxymethyl propyl triacrylate(TMPTA) through emulsion polymerition obtained the magnetic microspheres with the double bond on the surface. (3) amidation of the double bonds of magnetic microspheres on the surface with diethylenetriamine (DETA); (4) the multidentate amine modified magnetic microspheres was finally obtained by the reaction of amino groups on the surface of DETA modified magnetic microspheres with double bond of butyl acrylate (BA). Their chemical structures were confirmed by XPS, infrared spectrum (FTIR) and the nitrogen content in the particles was determined by elemental analysis (EA). Then, the multidentate amine immobilized on magnetic microspheres was used as ligand for CuCl in ATRA of CCl₄ with MMA and methyl trichloroacetate with St repeatly. The conversion and purity of the product were determined through the gas chromatography respectively. The results indicated that the multidentate amine modified magnetic microspheres ligand was synthesized successfully and the nitrogen content of this ligand is 1.0mmol/g. The multidentate amine modified silica gel is good catalytic ligand of ATRA reaction. This kind of ligand have been used five times in the ATRA reaction of carbon tetrachloride with MMA and the methyl trichloroacetate with St, and the conversion for the first time reached above 80% in 40 hours, when the fifth time still exceeded 35%. The third part: 1,1,1,3-tetrachloro-3-phenylpropane(TCPP), methyl 2,2,4-trichloro-4-phenylbutyrate(MTCPB), methyl 2-methyl-2,4,4,4-tetrarchlorobutyrate(MMTCB) and dimethyl 2,2,4-trichloro-4- methyl -glutarate (DMTCMG) have been synthesized via ATRA from styrene (St) and methyl methacrylate (MMA) with carbon tetrachloride and methyl trichloroacetate respectively. When the TCPP and MTCPB were used as initiators for ATRP of St and the MMTCB and DMTCMG were used as initiators for ATRP of MMA in the presence of the cuprous chloride (CuCl)/ 2, 2'-bipyridine catalyst system respectively, a controlled polymerization process was achieved with the resulting polystyrene (PS) and polymethyl methacrylate (PMMA) having number average molecular weights which increased with monomer conversion and narrow molecular weight distributions. The number average molecular weights and structure of the PS and PMMA characterized by ¹H NMR and gel permeation chromatography (GPC) showed that TCPP and MTCPB both act as bifunctional initiators for the ATRP of St and the functionalities of MMTCB and DMTCMG for the ATRP of MMA were 1.0 and 1.5 respectively.