Papers by Author: Jian Ping Deng

Abstract: Novel biocompatible tough hydrogels were prepared through free radical micellar polymerization of N-isopropylacrylamide (NIPAM) with ammonium persulphate (APS) as initiator, in which hydrophobic monomer stearyl acrylate (C18) underwent micellar polymerization in the presence of gelatin as emulsifier. FT-IR and DSC demonstrated the formation of co-polymer of NIPAM and C18. Swelling results indicated that hydrophobic polymer domains derived from C18 in aqueous medium acted as the physical crosslinking points by hydrophobic association. Uniaxial tensile test demonstrated the mechanical properties of hydrogels increased with increasing C18 and gelatin contents. The hydrogel exhibited low toxicity and promoted cell proliferation. The desirable toughness, low toxicity and the promoting effect of cell proliferation made the present hydrogels good candidates for tissue regeneration materials.

Abstract: In this study the vapour phase surface graft polymerization of acrylonitrile (AN) onto poly(ethylene terephthalate) (PET) film was conducted with benzoyl peroxide (BPO) as an initiator. Effects of reaction time and quantity of BPO on the polymerization were investigated. With the prolongation of reaction time, the graft polymerization took place rapidly at first, then slowed down, and leveled off. With the increase of BPO, the graft yield increased, then remained unchanged, and lastly began to decrease. The surface topography structure of the grafted PET film was observed by SEM. Grafted PET film was characterised by FTIR spectra, SEM photographs and contact angle measurement.

Abstract: Copolymerization of MAn and CHDDVE was conducted by using azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO) as the initiator, ethyl acetate (EA) or n-butyl acetate (BA) as the solvent, and n-hexane as the precipitator. Effects of several factors on monomer conversion were studied, such as reaction time, reaction temperature, composition of the monomer feed (MAn/CHDDVE) and initiator concentration. Molecular weight and its polydispersity and polymer material morphology were characterized by gel permeation chromatography (GPC) and transmission electron microscope (TEM) technologies, respectively. It was demonstrated that CTC was formed in MAn/CHDDVE system, based on ultraviolet-visible spectroscopy (UV-vis) analysis. The product was alternating copolymer with high crosslinking degree, so it could not be dissolved in common solvents, e.g. water, chloroform, N, N-dimethyl formamide (DMF), tetrahydrofuran (THF) and acetone (Ac).

Abstract: A novel approach to functionalize polypropylene (PP) is presented. This method consists of two steps. Firstly, oligomers of glycidyl methacrylate (GMA) were synthesized via UV photo-polymerization using benzophenone (BP) as initiator. Secondly, the GMA oligomers were grafted onto PP, which was initiated by the free radicals generated through the reactivation of semipinacol dormant groups in the oligomers. By this method, the functionalization of PP could be facilely achieved in a simple system without either organic peroxide initiator or monomer; additionally, degradation of the substrate PP was not observed. This presentation is mainly focused on the characterization of the grafted PP products by XRD, DSC and TGA measurements. It is demonstrated that the melting temperature, crystallinity and the initial decomposition temperature of the grafted PP were all increased, compared with those of the origin PP; the functionalization of PP led to the change of the crystal form from the mixed form of α and β into only α form.

Abstract: Polypropylene (PP) was modified by melt graft copolymerization with ε-caprolactone (ε-CL) in the absence of initiator. Fourier transform infrared (FTIR)
spectroscopy was used for qualitative and quantitative characterization of the reaction product. The graft copolymer was also characterized by 1H NMR, x-ray and thermogravimetric analysis (TG).

Abstract: Surface modification of low-density polyethylene (LDPE) films was carried out via a novel photografting polymerization technique with acrylamide (AAm) as the monomer. The photografting polymerization can be achieved via one-step method and two-step method. The photografting polymerization reactivity of AAm was examined with benzophenone (BP) as the photoinitiator and low-density polyethylene (LDPE) film as the substrate with “sandwich” assembly. Moreover, the occurrence and evolution of grafting polymerization of AAm on the substrate was demonstrated XPS analysis and SEM pictures.

Abstract: Lithium acrylate (LiAA) was applied as a functional monomer to modify the surface properties of polypropylene films via photografting polymerization in a precipitation reaction system. Two-step photografting polymerization technique was adopted with benzophenone (BP) as the photoinitiator and methanol as the solvent. ATR-FITR spectra proved the occurrence of grafting polymerization of LiAA on the substrate. Gravimetric analysis was performed to investigate the influences of some important factors on the photografting polymerization of LiAA. SEM was utilized to investigate the topography of the grafted film. The experimental results indicated that elongation of the irradiation time could increase the grafting yield (Yg) and Yg performed a maximum at a certain concentration of LiAA. SEM images showed that regular particles evenly dispersed on the surface of the grafted film.