Li Jiuqiang

Radiation preparation and thermo-response swelling of interpenetrating polymer network hydrogel composed of PNIPAAm and PMMA

Abstract Interpenetrating polymer network (IPN) hydrogel composed of hydrophilic poly( N -isopropylacrylamide) (PNIPAAm) and hydrophobic poly(methyl methacrylate) (PMMA) were synthesized by sequential IPN method using γ -rays from 60 Co source. Compared with pure PNIPAAm hydrogel, PNIPAAm/ PMMA IPN hydrogel not only behaved with obvious temperature sensitivity, but also had higher mechanical strength. The shrinking rate of the prepared IPN hydogel was slower than that of PNIPAAm hydrogel and the relative shrinkage was higher than that of PNIPAAm hydrogel. The IPN hydrogel with less PMMA was not stable while with more PMMA it was quite stable. In addition, the release of Methylene Blue (MB) from the IPN hydrogel was slower than that from PNIPAAm hydrogel as well.

Radiation synthesis and characteristic of IPN hydrogels composed of poly(diallyldimethylammonium chloride) and Kappa-Carrageenan

Abstract A new system of IPN hydrogels composed of diallyldimethylammonium chloride (DADMAC) and natural macromolecule, Kappa-Carrageenan (KC) were prepared by γ-irradiation. Their gel fraction and swelling behavior were studied. Elemental analysis and gel strength measurement results showed that there was an amount of KC that remained in the gels and the gel strength was enhanced obviously.

Radiation synthesis and characterization of polyDMAEMA hydrogel

Abstract Poly N, N-dimethylaminoethyl methacrylate (polyDMAEMA) hydrogels were synthesized by γ-irradiation technology, and the conditions of synthesis, such as total dose, dose rate, concentration of monomer and crosslinker in aqueous solution, were investigated. The property measurements of the hydrogels showed that they exhibited temperature sensitivity in a temperature range of 38–40°C and pH sensitivity at pH=2.5. They also had electric responsive behavior although it was not typical. The hydrogels synthesized were transparent and elastic and displayed good swelling behavior in water, therefore, they can be used as a kind of carrying material in drug delivery systems.

Radiation preparation of PVA-g-NIPAAm in a homogeneous system and its application in controlled release

Abstract Thermosensitive PVA-g-NIPAAm copolymers were prepared by graft copolymerization of N -isopropylacrylamide (NIPAAm) onto poly (vinyl alcohol) (PVA) in homogeneous system of dimethyl sulfoxide (DMSO) by 60 Co- γ irradiation at room temperature. The factors of affecting the grafting yield, such as radiation dose, dose rate, acid concentration, were investigated. It was found that the grafting yield was increased with dose up to 30 kGy, but decreased slightly with dose rate from 61.2 to 50.1 Gy/min. The acid concentration also had influence on the grafting yield. Then the hydrogel of PVA-g-NIPAAm copolymer was made through a freezing–thawing process. The PVA-g-NIPAAm hydrogel exhibited obvious thermal sensitivity, which was observed from the differences of swelling behavior in water at different temperatures (below or above LCST). In addition, the release of Methylene Blue (MB) from this kind of hydrogel was studied. The release rate of MB from PVA-g-NIPAAm copolymer hydrogel at 48°C was faster than that at 15°C due to the shrinkage of the hydrogel at 48°C.