Temperature / Ph-sensitive Block Copolymers And Click Chemistry Of Crosslinking

Double hydrophplic block copolymers with environmental sensitive can be used to prepare gel by copolymers inter-chains crosslinking. In recent years, the "click chemistry" has much attention for gelation of among the copolymers, the 1,3-dipolar cycloaddition of azide group (-N3) and alkynyl (-C≡CH) or cyano-group(-C≡N) especially. In this thesis, N, N-diehylacryamide (DEAM), N, N,-diethylamino ethyl methacrylate (DEAEMA),2-hydroxyethyl methacrylate (HEMA) were used to synthesize triblock compolymers P(HEMA-co-DEAEMA)-b-PDEAM-b-P(DEAEMA-co-HEMA), random compolymers P(DEAEMA-co-HEMA), random compolymers hydrogels, and study the properties of their aqueous solutions. The main results of this thesis are as follow:1. ABA type triblock compolymers poly (2-hydroxyethyl methacrylate-co-2-N, N-diethylamino ethyl methacrylate)-b-poly(N,N-diehylacryamide)-b-poly(2-hydroxy ethyl methacrylate-co-2-2-N,N-diethylamino ethyl methacrylate) P(HEMA-co-DEAEMA)-b-PDEAM-b-P(DEAEMA-co-HEMA) were synthesized via atom transfer radical polymerization (ATRP). The synthesized triblock copolymers were characterized by FT-IR,'H-NMR and GPC. The temperature and pH sensitivities of the triblock copolymer aqueous solutions were investigated by transmittance measurements, viscosity, laser particle size analysis, and transmission electron microscope. The results show that the resultant block copolymers have temperature and pH sensitivities, the LCST of the copolymers decreases with increasing of the HEMA content in the triblock copolymers, and the critical phase transition pH of the triblock copolymer solutions also decreses with increasing of the HEMA content in the copolymers. The micellization of triblock copolymers can be realized by changing of temperature or pH. The LCST and pKa of the block copolymers can be adjusted by controlling HEMA content in the copolymers.2. Random compolymers poly(2-hydroxy ethyl methacrylate-co-2-N,N-diethylamino ethyl methacrylate) P(DEAEMA-co-HEMA) were synthesized via atom transfer radical polymerization (ATRP). The hydroxy groups on the random copolymer P(DEAEMA-co-HEMA) chains were translated into azide groups through some appropriate reactions. A pH-sensitive hydrogel was prepared by click chemistry between the azide groups on the P(DEAEMA-co-HEMA) copolymer chains and the C=N groups on the polyacrylonitrile (PAN) chains. The microstructures of copolymer hydrogel were by characterized by scanning electron microscopy (SEM), swelling properties and pH sensitivities of hydrogels were studied by weighing method, and the drug loading properties and drug delivery of the hydrogel were studied. The results show that the pore size of hydrogel network decreased with the increasing of pH, and the swelling ratios increased with decreasing of pH, and the release cumulate amount of drug from gel could achieve the 78% in 12 h.