Temperature / Ph Sensitivity Of Block Copolymers Pdeam-b-pdmaema-b-pmaa Atrp And Their Micellization Study

Environmentally sensitive polymer is a class of polymer material which can respond and perceive on the environment conditions change, and it has an ability of features found. When the external environment physics or chemistry signal changes, the physical or chemical properties of the sensitive polymer will have some smart response. The sensitive polymer can form some special structure in some specific solution, such as micelles, vesicles aggregates of different shapes. They are used in the area of drug delivery, drug release, biomaterials and tissue engineering, et al. All hydrophilic block copolymers are composed of diblock or multiblock component, which have different chemical properties, and each block has a certain water-soluble. One of the block has the water-soluble character that can promote dissolution and dispersion, the other block can change into hydrophobic with externally environmental conditions change then obtained the all hydrophilic block copolymer micelle. The synthesis methods of the blocks copolymers are varise, such as ATRP, RATRP and RAFT, et al. Atom transfer radical polymerization (ATRP) polymerization as a method that takes the both advantages of the free radical polymerization and living radical polymerization which was used to synthesize amphiphilic block copolymer and all hydrophilic block copolymers.On the basis of the above research, we synthesized poly tert-butyl methacrylate (PtBMA), poly (N, N-diethyl acrylamide) (PDEAM) and poly (N, N-dimethylaminoethyl methacrylate) (DMAEMA) by ATRP technique. Researched temperature-sensitivity and pH-sensitivity of their aqueous solution by UV-vis transmittance measurements. On this basis, the block copolymer PtBMA-b-PDMAEM and PDEAM-b-PDMAEMA-b-PtBMA were synthesized using tBMA, DMAEMA and DEAM as monomers. The block copolymer PMAA-b-PDMAEMA and PDEAM-b-PDMAEMA-b-PMAA were obtained by synthesized block copolymers hydrolyzation. The main study results are as follows:1. A narrow molecular weight distribution of the poly butyl methacrylate (PtBMA), the poly methacrylic acid (PMAA), the poly (N, N-diethyl acrylamide) (PDEAM) and the poly (N, N-dimethylaminoethyl methacrylate) (PDMAEMA) were synthesized, bpy/CuBr as catalytic system, a-bromo propionate as initiator and methanol as solvent, by atom transfer radical polymerization (ATRP). We using UV-vis transmittance measurements studied sensitivities of polymer solutions. The results showed that PMAA,PDEAM and PDMAEMA are three different kinds of environmentally sensitive polymers. 2. The all hydrophilic block copolymers were synthesized by ATRP which are the poly tert-butyl methacrylate-b-poly (N, N-dimethylaminoethyl methacrylate) (PtBMA-b-PDMAEMA) and the poly methacrylic acid-b-poly (N, N-dimethylaminoethyl methacrylate) (PMAA-b-PDMAEMA). Their structures and properties were characterized by FT-IR,1H-NMR, GPC and TG; Using UV-vis transmittance measurements, digital viscometer, laser light scattering and transmission electron microscopy and we studied the environmental sensitivity and block copolymer micellization behavior. The results showed that the block copolymer has a dual pH-sensitivity. pH>9.0, the core-shell structure micelles were formed, PDMAEMA as core, and PMAA as shell; pH<6.0, the other kind core-shell structure micelles were formed, PDMAEMA as shell and PMAA as core.3. The poly (N,N-diethyl acrylamide)-b-poly (N, N-dimethylaminoethyl methacrylate)-b-poly tert-butyl (PDEAM-b-PDMAEMA-b-PtBMA) were synthesized by ATRP. The poly (N,N-diethyl acrylamide)-b-poly (N, N-dimethylaminoethyl methacrylate)-b-poly (PDEAM-b-PDMAEMA-b-PMAA) all hydrophilic block copolymers were obtained by the synthesized copolymers hydrolyzation. Their structures and properties were characterized by 1H-NMR and FT-IR; the molecular weight distribution was determined by GPC using UV-vis transmittance measurements, digital viscometer, laser light scattering and transmission electron microscopy. The results showed that the triblock copolymer PDEAM-b-PDMAEMA-b-PMAA has both temperature and pH sensitivity and the LCST depends on solution concentration and pH.