RAFT Polymerization Of The Monomer Containing Benzotriazole And Its Application In The Synthesis Of Functional Polymers

In this thesis, the reversible addition fragmentation chain transfer (RAFT) polymerizations of 2-[3-(2H-Benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate (BHEMA) were investigated. The functionality polymers based on Poly(BHEMA) (PBHEMA) with different structures were prepared by the methods of postfunctionalization and graft-polymerization. The contents of the work consisted of the two parts.Part 1: A well-defined poly{2-[3-(2H-Benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate} (PBHEMA) was first prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) and 2,2'-azobisisobutyronitrile (AIBN). Through the strategy of post-azo-functionalization, the bisazobenzene group was introduced into the side chains of PBHEMA. The resulting polymers containing benzotriazol and azobenzene group exhibited relatively higher molecular weight than original polymers, narrow molecular weight distributions (Mw/Mn = 1.17-1.26) and adjustable degree of functionalities. Also, the thermal stability and the glass transition temperature (T_g) of the polymers increased with the introduction of bisazo-chromophores. The molecular weight of polymer had slight effect on the T_g of the polymer. The polymer showed partially crystallization as the bisazo content excess 36%. Photoisomerization of bisazo polymer was measured under irradiation of a 488 nm Ar⁺ laser beam. Photoisomerization rate constant, k_exp, as measured at room temperature in THF solution, was 0.3 s^-1.Part 2: By the combination of reversible addition-fragment chain transfer polymerization (RAFT) and atom transfer radical polymerization (ATRP), amphiphilic double-grafted copolymers consisting of poly(ethylene glycol)methyl ether methacrylate (PEGMA) as the hydrophilic side chain and polystyrene (PS) as the hydrophobic backbone were synthesized by a'grafting from'process. The copolymers were characterized by gel permeation chromatography (GPC), ¹H nuclear magnetic resonance (¹H NMR) spectroscopy, ¹³C nuclear magnetic resonance (¹³C NMR) spectroscopy and FT-IR spectroscopy. The self-assembly behavior of the obtained amphiphilic double-grafted copolymers in deionized water was studied by high performance particle sizer (HPPS). The results showed that the Z-average size of the micelles in deionized water decreased with the increase of content of PEGMA. The morphologies of the micelles self-assembled from the resulting amphiphilic copolymers in deionized water were studied by transmission electron microscopy (TEM).