Dual Functional Groups Research Articles

Synthesis of antimicrobial silsesquioxane–silica hybrids by hydrolytic co-condensation of alkoxysilanes

Organically modified silicates represent an excellent example of organic–inorganic hybrids in materials science. The routes to achieve incorporation of organic functionalities include grafting and co-condensation (one-pot synthesis). Compared with the grafting method, the advantage of one-pot synthesis manifests as the tunability of both mechanical and biological properties. Herein, we report a silsesquioxane–silica hybrid (SqSH) with dual functional groups (alkylammonium and methacrylate chains) synthesized by the hydrolytic co-condensation of one tetraethoxysilane and two alkoxysilanes. Successful co-condensation is validated by attenuated total reflection-Fourier transform infrared (ATR-FTIR), 29Si nuclear magnetic resonance (29Si NMR), and thermogravimetric analysis (TGA). 3-(Trimethoxysilyl)propyldimethyloctadecyl ammonium chloride (SiQAC), one of the three precursors, simultaneously serves as a structure-directing agent in the modified Stober reaction, resulting in SqSH particles with structural hierarchy of both ordered lamellar structure and spherical morphology, as revealed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The SqSH particles bear tunable mechanical properties and, when incorporated into bis-GMA/TEGDMA resin, antimicrobial activities against Streptococcus mutans, Actinomyces naeslundii, and Candida albicans.

Improvement of thermal properties of biodegradable polymer poly(3-hydroxybutyrate) by modification with acryloyloxyethyl isocyanate

Poly(3-hydroxybutyrate) (PHB) is one type of polyhydroxyalkanoates often used as a biomedical material due to its biodegradable and biocompatible nature. However, the mechanical and thermal properties of PHB must be improved before it can be used in a wider variety of biomedical applications. To improve the thermal properties of biodegradable PHB, various reaction conditions were studied. Results demonstrate that reacting PHB with acryloyloxyethyl isocyanate (AOI), a monomer with dual functional groups, produces a modified PHB material with markedly improved thermal properties. The 10% thermal decomposition temperature for PHB modified with 5% AOI was 2978C, which was 26.88C higher than original PHB. The Tg also increased from 48 Ct o around 308C for AOI-modified materials. Additionally, due to the poly(ester-urethane) structure and hydrogen bonding of polymer materials, the mechanical properties also improved. Thus, this modified PHB biodegradable polymer may have greater application as a biomedical material due to its enhanced thermal and mechanical properties. POLYM. ENG. SCI., 52:1524–1531, 2012. a 2012 Society of Plastics Engineers

PH Responsive Hybrid Zwitterionomer for Protein Separation: Smart Nanostructured Adsorbent

Nanostructured zwitterionic (ZI) hybrid materials have great potential for protein separation/purification because of dual functional groups (acidic and basic) grafted on polymer matrix. Herein, we are reporting a versatile method for preparation of ZI monomer (N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulfopropyl) ammonium, DMMSA) by a simple epoxide ring opening reaction. The prepared adsorbent was highly stable and showed pH responsive protein adsorption (bovine serum albumin (BSA) and lysozyme (LYS) as the hmodel case). Adsorption kinetics revealed second order kinetics (Freundlich isotherm) and favorable adsorption of BSA and LYS. Separation of proteins was effectively achieved by isoelectric focusing, and the ZI nature of the adsorbent plays an important role. Moreover, more than 90% desorption of protein by changing the external environment with negligible loss (1–2%) in adsorption capacity indicates the practical applicability of the process.

Magnetic Nanoparticles Derivatized with Dual Functional Groups for Environmental Applications

In this study, the magnetic nanoparticles derivatized with dual functional moieties of dodecyl and mercapto were prepared, which characterized by X-ray diffraction (XRD), scanning electron microscope(SEM), surface area and pore size determination, fourier transform infrared spectrometry (FT-IR) and water contact angle analysis. The new material was proved to be an effective sorbent for environmental remediation.

Ampholyte polystyrene spheres self-regulated deposition of noble metal nanoparticles for catalyst applications

The polystyrene (PS) spheres having dual functional groups were synthesized using emulsifier-free emulsion polymerization based on St/potassium persulfate/water system in the presence of V-50 as co-initiator. Fourier transform infrared (FTIR) confirms the presence of the sulfate and the amino groups on the surfaces of PS spheres. Transmission electron microscopy and X-ray photoelectron spectra revealed that the PS spheres were successfully deposited with catalytic palladium (Pd) or gold (Au) nanoparticles (NPs). The reduction of 4-nitroaniline to 4-phenylenediamine used as a model reaction was performed for catalysis studies and examined by ultraviolet. It was found that both Au and Pd PS dispersions show high catalytic activity. The Pd PS dispersion of 200 μl with only Pd content of 1.09 wt.% exhibits an excellent catalytic effect superior to the commercial Pd/C catalyst, i.e., less than 35 s taken for the completion of the reduction of 4-nitroaniline.

A study of polyethylene-gr-2-tert-butyl amino methacrylate-supported TiCl4 catalyst for ethylene polymerization

The use of a polyethylene-based copolymer with dual functional groups (polyethylene-gr-2-tert-butyl amino ethyl methacrylate) as the support for TiCl4 catalyst in ethylene polymerization was studied. Different methods for treating the support were examined and treatment with BuMgCl was found to be the most effective. With the BuMgCl-modified support, a 12-run Plackett-Burman design was used to screen 11 factors in catalyst preparation. Statistical analysis of the results from this design identified significant factors with the amount of BuMgCl singled out to be the most important one for the four response variables of interest, Mg loading, Ti loading, catalyst activity per gram catalyst, and catalyst activity per gram Ti. © 1996 John Wiley & Sons, Inc.