Nas-mediated Amidation Of The Environmental Sensitivity Of Block Copolymers And Phase Behavior Studies

Environmentally sensitive polymer was a smart of material with great sensitivity to environment, mostly including temperature-sensitive polymer, pH-sensitive polymer, photosensitive polymer and so on. Double hydrophilic block copolymers were composed of two or more the water-soluble blocks, which can self-assemble into micelles in the completely hydrophilic environment with the change of temperature, pH or the addition of other ions. Block copolymer micelles were important in many field of applications such as drug delivery, cleaning up the environment, sewage treatment and so on. Atom transfer radical polymerization (ATRP) is a common method to prepare block copolymers. ATRP method has its advantages such as a wide range of application of monomers, and moderate reaction conditions.Based on the above research background, P(DEAM-co-NAS) was synthesized by free radical solution polymerization. We studyed the temperature sensitivities of P(DEAM-co-NAS) aqueous solutions in different copolymer composites and different properties of the medium environment. Then diblock copolymers PDEAM-b-PNAS and PDEAEMA-b-P(DEAM-co-NAS) were synthesized by atom transfer radical polymerization (ATRP), with further study of the properties of copolymer in aqueous solution and micellar behavior. Specific study as follows:1. Poly(N, N-diethylacrylamide-co-N-acryloxysuccinimide) P(DEAM-co-NAS) was synthesized by free radical solution polymerization. Structures of the copolymers were characterized by FT-IR and 1H NMR. Copolymer composites and properties of the medium environment on the temperature sensitivities of P(DEAM-co-NAS) aqueous solutions have significant influences. The results show that LCST of P(DEAM-co-NAS) aqueous solution rised with increasing NAS contents. The addition of salts resulted in a linear decrease of the LCST of P(DEAM-co-NAS) aqueous solution which depended on the anion valence of the salts. The addition of organic acids can-reduce the LCST of the P(DEAM-co-NAS) aqueous solution. Moreover, the addition of ethylenediamine and putrescine can lead to an increase of the LCST of the P(DEAM-co-NAS) aqueous solution, and the effects of ethylenediamine and putrescine on the LCST of the P(DEAM-co-NAS) aqueous solution were greater than that of NaOH.2. PDEAEMA-b-P(DEAM-co-NAS) diblock copolymer was synthesized via ATRP. The copolymer has double the sensitivity of temperature and pH. Structures of the copolymers were characterized by 1H NMR and GPC. In aqueous solutions, via UV-visible spectrum the light transmittance of block copolymer was impacted by the environment changed in aqueous solution, the micellization behavior of PDEAEMA-b-P(DEAM-co-NAS) was studied by laser light scattering (LLS) and TEM. The results showed that: a narrow molecular weight distribution of the copolymer was synthesis. PDEAEMA-b-P(DEAM-co-NAS) can formed micelles with PDEAEMA cores and P(DEAM-co-NAS) shell above pH 8.2 and 25℃, copolymer also can formed "inverted" micelles with PDEAEMA shell and P(DEAM-co-NAS) cores above 45℃and pH 7.0. When the ethylenediamine was added to "inverted" micelles then to form shell cross-linked micelles; the structures of this micelles are specially stable, they are not influenced of circumstances.3. PDEAM-b-PNAS diblock copolymer was synthesized via ATRP. The structure and molecular weight of polymers were characterized by FT-IR,1H NMR and GPC; we studied the thermo-sensitivities by UV in aqueous solutions; the micellization behavior of PDEAEMA-b-PNAS was studied by TEM. The results showed that: a narrow molecular weight distribution of the copolymer have been prepared, and the copolymer was temperature-sensitivity; copolymer can be formed micelles with PNAS shell in selective solvents.