Zhi Yong Wei

Fabrication and Characterization of P34HB Scaffolds with Oriented Microtubules

Sponge-like scaffold with a specific three-dimensional structure resembling the actual extracellular matrix of a particular tissue show significant potential for the regeneration and repair of damaged anisotropic tissues. In this research, an oriented microtubular P34HB scaffold was prepared successfully. The mechanical property showed that anisotropy of modulus is much greater than a typical non-oriented scaffold. Altering the P34HB concentration allowed P34HB scaffolds to be produced with complex pore orientations, and anisotropy in pore size and alignment.

Synthesis of PCL / Graphene Oxide Composites by In Situ Polymerization

Recently, Graphene oxide (GO) has attracted enormous interests due to its extraordinary properties. GO sheets are expected to find a variety of applications, such as GO-based composites materials and biotechnology. The nanocomposites of Poly (ε-caprolactone) (PCL) and graphene oxide (GO) were successfully synthesized by in-situ polymerization. WAXD indicated that the PCL/GO composites formed an exfoliated structure. And Polarized Optical Image (POM) showed that the graphene oxide could be homogeneously dispersed in matrix. What’s more, we also studied the crystallization behavior of the pure PCL and PCL/GO nanocomposites as well as the effects of graphene oxide as the nucleation agent.

Preparation and Properties of Water-Based Solar-Reflective Coatings with Color Hollow Ceramic Microsphere

We have developed a system of solar reflective coatings that can reflect the sunlight then reduce the temperature of coated surface. The base layer material, fluorinated polystyrene-acrylate copolymers water-based emulsion was firstly prepared with hexafluoro butyl methacrylate(HFBA), styrene(St), butyl acrylate(BA), methyl methacrylate (MMA) by pre-emulsion copolymerization method. The effect on copolymerization and emulsion properties were investigated, and the polymerization condition was optimized. A hollow ceramic micro-sphere was used as the main reflective functional fillers in the system. We had a test on the practical heat-insulating properties on a prototype device. The result showed that temperature difference of the surface was reached as 6.5 °C. The new type of reflective coatings also has good stability and durability.

Facile Graft Copolymerization of Chitosan Powder with Methyl Acrylate Using Ceric Ammonium Nitrate

Chitosan-g-MA was prepared with methyl acrylate using ceric ammonium nitrate (CAN) as an initiator under nitrogen atmosphere in aqueous solution and characterized by FTIR spectroscopy. The effects of concentration of CAN, the amount of MA, reaction temperature on graft copolymerization were studied by determining the grafting percentage and grafting efficiency. The maximum grafting percentage and grafting efficiency obtained under these conditions were 640 % and 68 %, respectively.

Synthesis, Characterization and Properties of Poly(L-Lactic Acid-Co-α- Phenylalanine) Obtained by Direct Melting Copolymerization

A new poly(ester amide)s (PEA) derived from L-lactic acid and L- phenylalanine have been synthesized by melting copolymerization with p-toluenesulfonic acid (TSA), stannous chloride (SnCl2) as catalyst. The products were analyzed by NMR, FT IR. The effects of the content of L-phenylalanine on the copolymers structure were studied. Being the phosphate buffered saline (pH=7.2) as the degradation solution, it had been found that the degradation rate speed up with the increasing the content of the L- phenylalanine.

Ring Opening Polymerization of ε-caprolactone Catalyzed with Magnesium Lactate

The aim of this paper is to present a synthesis method of poly(ε-caprolactone) by the ring opening polymerization of ε-caprolactone catalyzed with nontoxic magnesium lactate. The results indicated that Mg(Lac)2 is a catalyst with moderate activity for the polymerization of ε-caprolactone. Effects of the catalyst and reaction temperatures on the microstructure of the ε-caprolactone and L-lactide copolymers were investigated by means of 13C-NMR spectroscopy. An increase in the reaction temperature enhances the role of transesterification and the extent of randomness.

Advances in Synthesis and Properties of Poly(ε-caprolactone)/Carbon Nanocomposites

Recently, Graphene oxide (GO), carbon nanotubes (CNTs) and fullerenes (C60) have attracted enormous interests because of their extraordinary properties, and they can improve various kinds of properties of polymeric materials. The latest achievements on investigating applications and properties including mechanical properties, thermal properties, crystallization behavior and bioactivity of poly (ε-caprolactone). (PCL)/GO, PCL/CNTs and PCL/ C60 nanocomposites obtained in the last five years were summarized in this paper. The relationships between the properties of nanocomposites and the loading, dispersion chemical modification of GO, CNTs and C60 were also discussed.

Degradation Experiments and Modeling of PLGA Blend and Gradient Films

PLGA blend and gradient films were designed and prepared to improve the late degradation properties of PLGA films. The gradient films were composed of gradual components of PLGA50/50 and PLGA 75/25, and PLGA 50/50, featuring gradual descents from outside parts to inside parts of the films. Degradation processes of biodegradable PLGA blend and gradient films were also predicted by Monte Carlo simulation to understand the mechanism of degradation. The simulation results indicated that the gradient structure prolonged the mass transfer time of the degradable films, and it induced smoother weight loss than single-component or blend films. The degradation behaviors of single-component, blend and gradient films were experimentally investigated to prove the validity of the models by immersing them into PBS. The experiment indicated that the gradient films have the most stable weight loss curves, which were in well accordance with the simulation by Monte Carlo method.

Synthesis, Microstructure and Properties of Poly(L-Lactic Acid-Co-α-Alanine) Obtained by Direct Melting Copolymerization

A new poly(ester amide)s (PEA) derived from L-lactic acid and α-alanine have been synthesized by melting copolymerization with p-toluenesulfonic acid (TSA) with stannous chloride (SnCl2) as catalyst. The products were analyzed by NMR, FT IR techniques. The effects of the content of α-alanine (L-Ala) on the copolymers structure were studied. Being the phosphate buffered saline (pH=7.2) as the degradation solution, the degradation rate speed up with the increasing the content of the α-alanine.

A Study of Thermal Performance on Cool Colorful Water-Based Reflective Coatings for Building

This paper presented the results of a comparative study aiming to investigate the effect of reflective coatings on lowering surface temperatures of matrix. Moreover, the important factors of the amount and the color of colored hollow-ceramic micro sphere were discussed. It was demonstrated that the use of reflective coatings could reduce a white surface temperature by 6.5 °C compared to a sample. The temperature difference became to reduce while the color of coatings turned to dark from the white to the yellow.