Search results for "polymerization"

Novel poly (ionic liquid)-based anion exchange membranes for efficient and rapid acid recovery from industrial waste

2020

Abstract Owing to the less energy consumption, positive impact on the environment, and prospect of providing clean water resources, anion exchange membranes (AEMs) are promising materials for acid recovery from various industrial wastewater/effluent. Based on the diffusion dialysis process, AEMs selectively allow rapid proton permeation while efficiently retaining metal ions. To enhance the efficiency of the acid recovery process, precise control of macromolecular architecture and chemical composition that enables high hydrophilicity, proton conductivity through the membrane, and ion exchange capacity is required. In this direction, we report on the one-step fabrication of novel poly (ionic…

Stereocomplex Formation in Polylactide Multiarm Stars and Comb Copolymers with Linear and Hyperbranched Multifunctional PEG

2013

Biodegradable tablets having a matrix of low molecular weight poly-L-lactic acid and poly-D,L-lactic acid.

1990

Biodegradable Homo- and Copolymers of lactic and glycolic acids have been used for manufacture of microparticles and matrix implants1,5). To ensure sufficient hydrolytic matrix stability lactic acids of high and medium degree of polymerization have been used. The manufacture of poly lactic acid tablets with an average molecular weight of 25000 and 6000 was reported recently, after finishing the following study2). Bioabbaubare Gerusttabletten aus niedermolekularer poly-L-Milchsaure und poly-D,L-Milchsaure

Development of pipette tip-based poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolith for the extraction of drugs of abuse from oral flu…

2019

Abstract In this work, a monolithic polymer based on poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-co-EDMA) was prepared inside 200 μL pipette tips for the extraction of drug of abuse from oral fluid samples. After an appropriate surface tip modification, several polymerization mixtures with different monomer/cross-linker ratios, and percentage of porogen were studied. The most appropriate monolith to easily flow organic solvents and oral fluid samples was prepared with a MAA/EDMA ratio of 8:92 wt/wt and dodecanol containing 10 wt% toluene, as porogenic solvent. Parameters affecting the extraction procedure were evaluated and the monolith was characterized in terms of bindin…

Micelles of polyisobutylene-block-poly(methacrylic acid) diblock copolymers and their water-soluble interpolyelectrolyte complexes formed with quater…

2004

The micellization of ionic amphiphilic diblock copolymers, polyisobutylene-block-poly(methacrylic acid) (PIB-b-PMAA), with a constant degree of polymerization of the non-ionic block ðDPn ¼ 20Þ and various degrees of polymerization of the polyelectrolyte block ðDPn ¼ 100 – 425Þ was examined in aqueous media by means of fluorescence spectroscopy using pyrene as a polarity probe. The molar values of the critical micellization concentration (cmc) were found to be around 2 £ 10 26 mol/l, being nearly independent of the length of the polyelectrolyte block as well as pH (in the range 6 – 9) and ionic strength (# 0.5 M NaCl) while the specific cmc values varied from 20 to 100 mg/l. Small-angle neut…

1990

It is shown that the block-like structure of the polyampholyte poly(methacrylic acid)-block-poly(1-methyl-4-vinylpyridinium chloride) considerably influences its conformational behaviour. This specific behaviour is explained by the formation of intra-macromolecular polyelectrolyte complexes stabilized by cooperative ionic contacts between acidic and basic units near the isoelectric point (i. e. p.). The structure of the block-polyampholyte at the i. e. p. is suggested to be close to the structure of non-stoichiometric polyelectrolyte complexes. The complex formation ability of the block-polyampholyte with respect to anionic, cationic, and nonionic polymers is also studied. By means of poten…

Leach-Proof Sol–Gel Microcapsules as Curing Agents for One-Pot Thermosetting Resins

2013

The sol-gel microencapsulation of free-radical initiator benzoyl peroxide in sol-gel methyl-modified silica microcapsules of core/shell geometry allows curing of acrylate-based polyurethane and polyester resin formulations sprayed from a pressurized can without the need to compartmentalize reactants from the initiator to cross-link. These results open the route to widespread application of sol-gel microcapsules to efficiently cure polymer and composite mixtures that are widely used as functional coatings, molding compounds, adhesives, and sealants.

Solid state polymerization of new polyesters containing diacetylenic groups

1986

Synthesis and properties of some new polyesters of 10, 12-docosadiyn-1, 22-diol are described. The diyn-polyesters as films became coloured polydiacetylenic films on exposure to UV radiation and their properties were studied.

High crystallinity polyethylene obtained in biphasic polymerization using pyridinium chloroaluminate ionic liquid

2014

A series of N-n-alkylpyridinium chloroaluminate ionic liquids [C n -py][AlCl4] (where n-alkyl = n-butyl, n-hexyl, and n-octyl) was applied as a medium of the Cp2TiCl2 catalyst, activated by AlEtCl2 or AlEt2Cl, to evaluate the influence of the studied ionic liquids on the performance of the biphasic ionic liquid/hexane ethylene polymerization and the properties of the produced polyethylene (PE). The best results were obtained using N-n-butylpyridinium chloroaluminate. The polyethylene obtained in the biphasic polymerization have the high crystallinity, which was confirmed by DSC, WAXS and PALS methods, as well as the bulk density comparable to commercial HDPE. These unique properties results…

Gold nanostars coated with neutral and charged polyethylene glycols: A comparative study of in-vitro biocompatibility and of their interaction with S…

2015

Gold nanostars (GNS) have been coated with four different polyethylene glycols (PEGs) equipped with a -SH function for grafting on the gold surface. These PEGs have different chain lengths with average MW = 2000, 3000, 5000 and average number of -O-CH2-CH2 - units 44, 66, and 111, respectively. Two are neutral and two are terminated with -COOH and -NH2 functions, thus bearing negative and positive charges at physiological pH, thanks to the formation of carboxylate and ammonium groups. The negative charge of the GNS coated with PEG carboxylate has also been exploited to further coat the GNS with the PAH (polyallylamine hydrochloride) cationic polymer. Vitality tests have been carried out on …