Polymer Microspheres with Active Carboxyl Groups: Preparation, Structure and Hydrophilicity
State Key Laboratory of Hollow Fiber Membrane Materials and Processes, School of Environmental and Chemical Engineering, Tianjin Polytechnic University, 300160 Tianjin, PR China.Journal of Nanoscience and Nanotechnology (Impact Factor: 1.56). 12/2011; 11(12):11167-70. DOI: 10.1166/jnn.2011.4041
A quantitative research of microspheres, poly(ethylene glycol dimethacrylate-co-acrylic acid) (P(EGDMA-co-AA)) and poly(divinvlbenzene-80-co-acrylic acid) (P(DVB-co-AA)), with active carboxyl groups on surface prepared by distillation-precipitation polymerization was presented in this paper. The loading capacity of active carboxyl group on microspheres which was investigated by titration technique would be increased and the contact angle was decreased following the increase of the feed ratio of acrylic acid (AA) monomer. This phenomenon indicated that the hydrophilicity of particles was mainly determined by the feed ration of hydrophilic AA monomer. However, when the AA fraction was at a fixed level, a slight difference of the loading capacity of carboxyl groups on microsphere surfaces with different crosslinkers existed. The microspheres with EGDMA as crosslinker had a higher loading capacity of carboxyl groups and lower contact angle than those of P(DVB-co-AA) microspheres, which indicated that P(EGDMA-co-AA) microspheres were more hydrophilic than P(DVB-co-AA) microspheres.
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ABSTRACT: Herein, physicochemical features of poly(acrylic acid-co-acrylamide) hydrogels were studied via swelling, SEM, TGA, DTA and thermoporometric measurements as well Monte-Carlo simulations. Physicochemical characteristics of metal-embedded hydrogel nanocomposites were investigated by ICP-OES, XRD, SEM/EDX and HRTEM analysis. Catalytic behaviour of nanocomposites was examined through multi-repetitive oxidative degradation of methylene blue (MB) from wastewater. Decay of MB concentrations was followed up kinetically by UV-vis spectrophotometer and TOC analyzer. Poly(acrylic acid-co-acrylamide) hydrogels are promising candidates for embedding diverse-shaped nano-sized metallic species (Co, Cu, Ni and Fe) with advanced protectiveness behaviour against deactivation during degradation processes. Surface-sited nanometals developed pseudo-first ordered degradation profiles with inferior reusability trends. Bulk-sited nanometals exhibited strong tendency toward MB mineralization, obeying pseudo-second ordered progression. Hydrogel embedding nickel nanocomposite served as typical Auto-active catalyst regarding to its ability to gather reactants and radicals beneath nanometallic particles deep inside monolithics, thereby preserving the reduced metallic form throughout the degradation processes.
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ABSTRACT: This work focused on designing three-categorized polymeric forms; carboxylic-enriched, amide-enriched and equi-rationed amide-carboxylic hydrogels. Such hydrogels were analyzed using swelling, Monte-Carlo simulations, TGA, zeta-potential measurements, SEM and AFM. Their adsorption behaviors were examined using methylene blue dye. Effect of pH, adsorption isotherms, kinetics, temperature and adsorbent reproducibility were deliberated. All adsorption processes described by Dubinin–Radushkevich model following pseudo-second order kinetics. Carboxylic-enriched hydrogel showed negatively-charged smooth surfaces with unusual ulcer-like holes, which played the chief role in dyeing removal from wastewater with superior reproducibility. Increasing amide ratios in hydrogels encouraged electrostatic and chemical interactions with dye molecules and deteriorated adsorbent reproducibility.
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