Azo Polymers With Electronical Push And Pull Structures Prepared Via RAFT Polymerization And Its Photoinduced Birefringence Behavior

In this thesis, two methyl acrylate monomers containing electronical push or pull substituted azobenzene ring, e.g. MACP with cyano substituted and MAMP with methoxy substituted, were synthesized and polymerized using 2-cyanoprop-2-yl dithiobenzoate (CPDB) as chain transfer agent and 2,2'-azobisisobutyronitrile (AIBN) as initiator. The results showed that the polymerization consisted with"living"/controlled free radical polymerization characteristics. Thus, the obtained polymers, polyMACP (pMACP) and polyMAMP (pMAMP), had controlled molecular weight and narrow molecular weight distribution. The chain extension experiments of these two polymers using styrene as the second monomer were successfully carried out. The photo-induced trans-cis-trans isomerization kinetic of pMACP and pMAMP in chloroform solution were described. Marked differences in rate for the trans-cis and cis-trans isomerization of pMACP and pMAMP were observed in chloroform solution due to the different electronic effect in these two polymers. Photoinduced birefringence and surface relief grating (SRG) of the pMACP and pMAMP were investigated in thin film state. On the other hand, the attempts to synthesize random copolymers of methyl methacrylate (MMA) and with azobenzene side functionalized methyl methacrylate monomer, MAMP, via reversible addition-fragmentation chain transfer polymerization (RAFT) were made in search for a way to obtain functionalized-PMMA with well defined molecular structure. Copolymers with different azobenzene moieties content, e. g. from 12 mol % to 100 mol %, were obtained by varying the feed ratio of MAMP and MMA. The reactivity ratios of these two monomers have been measured via the modified Kelen-Tüdos method. The glass transition temperature of the samples was measured by DSC. Photoinduced cis-tans-cis isomerization of azobenzene moieties in copolymer solution was studied at room temperature. Cast films of copolymers with different azobenzene moieties content were characterized by photo-induced birefringence and surface relief grating (SRG).