Polydopamine-Modified Al2O3/Polyurethane Composites with Largely Improved Thermal and Mechanical Properties.

Alumina/polyurethane composites were prepared via in situ polymerization and used as thermal interface materials (TIMs). The surface of alumina particles was modified using polydopamine (PDA) and then evaluated via Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and Raman spectroscopy (Raman). Scanning electron microscope (SEM) images showed that PDA-Al2O3 has better dispersion in a polyurethane (PU) matrix than Al2O3. Compared with pure PU, the 30 wt% PDA-Al2O3/PU had 95% more Young's modulus, 128% more tensile strength, and 76% more elongation at break than the pure PU. Dynamic mechanical analysis (DMA) results showed that the storage modulus of the 30 wt% PDA-Al2O3/PU composite improved, and the glass transition temperature (Tg) shifted to higher temperatures. The thermal conductivity of the 30 wt% PDA-Al2O3/PU composite increased by 138%. Therefore, the results showed that the prepared PDA-coated alumina can simultaneously improve both the mechanical properties and thermal conductivity of PU.

Adsorption of phenolic compounds from aqueous solution using salicylic acid type adsorbent.

In this study, 5-aminosalicylic acid (5-ASA) was successfully grafted onto the poly(glycidyl methacrylate) (PGMA) macromolecular chains of PGMA/SiO(2) to obtain adsorbent ASA-PGMA/SiO(2). The adsorption properties of ASA-PGMA/SiO(2) for phenolic compounds were studied through batch and column methods. The experimental results showed that ASA-PGMA/SiO(2) possesses strong adsorption ability for phenolic compounds, and its adsorption capacity for phenol, 4-chlorophenol, and p-nitrophenol reaches 1.0, 1.1, and 1.32 mmolg(-1), respectively. In addition, pH has a great influence on the adsorption capacity. The adsorption isotherm data obeyed the Langmuir model well than Freundlich model. The desorption of phenolic compounds from the ASA-PGMA/SiO(2) adsorbent was most effectively achieved in a 0.1 molL(-1) sodium hydroxide solution. Consecutive adsorption-desorption experiments showed that the ASA-PGMA/SiO(2) adsorbent could be reused almost without any loss in the adsorption capacity.

Immobilization of povidone-iodine on surfaces of silica gel particles and bactericidal property.

A novel antibacterial material I(2)-PVP/SiO(2), on which povidone-iodine (PVP-I(2)) was loaded, was synthesized by a two-step route. Polyvinylpyrrolidone (PVP) was firstly graft-polymerized onto the surfaces of micro-sized silica gel particles, obtaining the grafted particles PVP/SiO(2). Subsequently, the grafted particles PVP/SiO(2) were allowed to undergo a complexation reaction with iodine, resulting in a water-insoluble antibacterial material, I(2)-PVP/SiO(2). The effects of various factors on the complexation reaction were examined. The antibacterial property of I(2)-PVP/SiO(2) was investigated by using Escherichia coli (E. coli) as model bacterium and with the colony count method. The experimental results show that the fitting temperature for the complexation reaction between PVP/SiO(2) and I(2) is 60 degrees C, and the complexation reaction reaches equilibrium after 12 h. The particles I(2)-PVP/SiO(2) have very strong antibacterial activity and they have the sterilizing mechanism similar to povidone-iodine.

Preparation of surface molecularly imprinted polymeric microspheres and their recognition property for basic protein lysozyme.

The surface imprinting of basic protein lysozyme (Lys) was carried out by designing a new route. The copolymerization of N-vinylpyrrolidone (NVP) and 2-hydroxyethyl methacrylate (HEMA) was first conducted in an inverse suspension polymerization system, and the crosslinked copolymeric microspheres HEMA/NVP were prepared. Subsequently, the esterification reaction of methacryloyl (MAO) chloride with the hydroxyl groups on the surfaces of HEMA/NVP microspheres was performed, and the modified microspheres MAO-HEMA/NVP, on which a mass of polymerisable double bonds were introduced, were obtained. In the presence of lysozyme, by initiating of K(2)S(2)O(8)-NaHSO(3), the monomer methacrylic acid (MAA) in the solution was crosslink-polymerized on the surfaces of MAO-HEMA/NVP microspheres, resulting in the surface imprinting of lysozyme. After removing the template molecules, the lysozyme molecule-surface-imprinted material MIP-HEMA/NVP was obtained. Because there were strong interactions between lysozyme and monomer MAA, electrostatic interaction and hydrogen bonding, the lysozyme molecule-surface imprinting was successfully realized. The MIP-HEMA/NVP microspheres have very high binding affinity for lysozyme, and the binding capacity gets up to 216 mg/g. It is more important that MIP-HEMA/NVP microspheres have specific recognition selectivity for lysozyme, and the selectivity coefficient for lysozyme with respect to bovine hemoglobin (BHb), which was used as a contrast protein in the experiments, actually reaches 31.07. In the respect of protein imprinting, the imprinting material with such high performance is unwonted.

Preparation and recognition performance of cytisine alkaloid-imprinted material prepared using novel surface molecular imprinting technique.

Methacrylic acid was first graft-polymerized on the surfaces of micron-sized silica gel particles in the manner of "grafting from" using 3-methacryloxypropyl trimethoxysilane as an intermedia, obtaining the grafted particle polymethacrylic acid PMAA/SiO(2). By adopting the novel surface-molecular imprinting technique put forward by us, cytisine molecule-imprinted material MIP-PMAA/SiO(2) was prepared with ethylene glycol diglycidyl ether as crosslinking agent. The binding characteristics of MIP-PMAA/SiO(2) towards cytisine was investigated in depth with both batch and column methods and using matrine and oxymatrine as two contrast alkaloids, which with cytisine coexist in sophora alopecuroides and their chemical structure is similar to cytisine to a certain extent. The experimental results show that the surface-imprinted material MIP-PMAA/SiO(2) has excellent binding affinity for cytisine (20.1 g/100 g of binding capacity), and it is more important that MIP-PMAA/SiO(2) has very high recognition selectivity for cytisine in relation to the two contrast alkaloids. The selectivity coefficients of the grafted particles PMAA/SiO(2) (non-imprinted material) for cytosine in relation to matrine and oxymatrine are only 1.03 and 1.06, respectively, displaying no recognition selectivity for cytisine. However, after imprinting, the selectivity coefficient of MIP-PMAA/SiO(2) for cytisine in respect to matrine and oxymatrine are remarkably enhanced to 12.08 and 15.05, respectively.