Study On Synthesis And Properties Of Hydrogel Based On Poly(N,N-diethylacrylamide) With Response To Temperature And PH

In this thesis, five different kinds of hydrogel, P(N,N-diethylacrylamide-co-N-hydroxymethyl acrylamide) (P(DEA-co-NHMAA)) hydrogel, P(N,N-diethyl-acrylamide-co-(2-dimethylamino) ethyl methacrylate) (P(DEA-co-DMAEMA)) hydrogel, P(DEA-co-DMAEMA)-g-P(DEA-co-DMAEMA) hydrogel, poly(diallyldimethyl- ammonium chloride)/poly(N,N-diethylacrylamide) (PDADMAC/PDEA) semi-IPN hydrogel, carrageenan-g-poly(methacrylic acid)/poly(N,N-diethylacrylamide) (KC-g- PMAA/PDEA), were prepared using free radical solution polymerization, macro- monomer grafting polymerization and semi-interpenetrating polymerization. The effects of the feed components, temperature and pH on the swelling behavior of the hydrogels were studied, and the rapid response properties of the hydrogels were investigated in detail, and the results are summarized as following:1. P(N,N-diethylacrylamide-co-N-hydroxymethyl acrylamide) (P(DEA-co-NHMAA)) hydrogels were synthesized by changing the initial DEA/NHMAA mole ratio, N,N'-methylenebisacrylamide and total monomer concentration. At FTIR spectra, it can be concluded that the P(DEA-co-NHMAA) hydrogel was successfully prepared. The interior morphology of the hydrogels illustrates the dependence of the morphology on the hydrogel compositions. In comparison with the PDEA hydrogel, the equilibrium swelling ratio (ESR) and lower critical solution temperature (LCST) of the hydrogels increase with the increase of NHMAA content in the feed. The release behaviors of the model drug, aminophylline, are found dependent on hydrogel composition and environmental temperature. In addition, the drug release mechanism of the drug-loaded hydrogels was analyzed by Peppa's potential equation.2. P(N,N-diethylacrylamide-co-(2-dimethylamino) ethyl methacrylate) (P(DEA-co-DAMEMA)) hydrogels were synthesized by changing the initial DEA/DAMEMA mole ratio. The hydrogels were characterized using Fourier transform infrared (FTIR) spectroscope, elemental analysis method and scanning electron microscope (SEM). It can be concluded that the P(DEA-co-NHMAA) semi-IPN hydrogel was successfully prepared. The P(DEA-co-DMAEMA) hydrogels have porous structure with more interconnected channel-like pores surrounded with thin walls and presented a sponge-like morphology. The capability of the temperature and pH of stimulating hydrogels is enhanced when the content of DMAEMA in the hydrogels increases. In comparison with the PDEA hydrogel, the deswelling and reswelling rates of the hydrogels increase with the increase of DAMEMA content in the feed. PDEA and P(DEA-co-DMAEMA) have no apparent cytotoxicity. The absorb and release behaviors of the model drug, bovine serum albumin, were found dependent on hydrogel compositions and environmental temperature, which suggests that these materials have potential application as intelligent drug carriers.3. The dual sensitive comb-type grafted hydrogels were synthesized by grafting polymeric chains with freely mobile ends, which were composed of both N,N-diethylacrylamide (DEA) and (2-dimethylamino) ethyl methacrylate (DMAEMA), onto the backbone of crosslinked P(DEA-co-DMAEMA) networks. The structure of the poly(DEA-co-DMAEMA) macromonomer was characterized by Nuclear Magnetic Resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR). The experiment results show that the P(DEA-co-DMAEMA) macromonomer was successfully prepared. Due to the pendant poly(DEA-co-DMAEMA) grafts providing spatial hindrance, the G-PDD hydrogels have an interconnected and macroporous network structure. The G-PDD hydrogels exhibite improved thermo- and pH-sensitive characteristics, such as faster deswelling and reswelling rates and great oscillating deswelling/swelling behavior, and the level of improvement depends on the poly(DEA-co-DMAEMA) macromonomer content.4. A novel semi-interpenetrating polymer network (semi-IPN) hydrogel of poly(diallyldimethylammonium chloride)/poly(N,N-diethylacrylamide) (PDADMAC/ PDEA) was prepared at room temperature. Differential scanning calorimetry (DSC) studies show that the freezing water content is found to accumulate with the increasing concentration in PDADMAC, which means a raise in hydrogen bond formation between the hydrophilic chains and the water molecules. The semi-IPN hydrogels exhibite improved thermosensitive characteristics, such as faster deswelling and swelling rates and great oscillating deswelling-swelling behavior, and the level of improvement depends on the PDADMAC content. The swelling dynamic transport of the hydrogels was analyzed based on the Fickian equation. These results show that the swelling mechanism would be transformed from Fickian diffusion to non-Fickian transport.5. A novel semi-interpenetrating polymer network (semi-IPN) hydrogel of kappa-carrageenan-g-poly(methacrylic acid)/poly(N,N-diethylacrylamide) (KC-g-PMAA/PDEA) was prepared. At FTIR spectra, it can be concluded that the KC-g-PMAA and Semi-IPN hydrogel was successfully prepared. The results show that the introduction of KC-g-PMAA do not change the lower critical solution temperature of the semi-IPN hydrogels, which is the same to the PDEA hydrogel (at 31℃). With the increase of KC-g-PMAA content, the thermo- and pH-sensitivity of the hydrogel are improved, which the swelling rate increases with the increasing content of KC-g-PMAA. The semi-IPN hydrogels show a faster deswelling and swelling rate. The swelling dynamic transport of the hydrogels was analyzed based on the Fickian equation. These results show that the swelling mechanism would be transformed from Fickian diffusion to non-Fickian transport. As the KC-g-PMAA content increase to some extent, Semi-IPN hydrogel swelling process would be more complicated, since it exhibits an overshooting phenomenon.