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Melt processing of poly(l-lactic acid) (PLLA) can lead to both molar mass reduction and colour formation, which can alter properties critical for medical applications (e.g. biodegradation rate). In this work, ultra-violet/visible (UV–vis) spectroscopy was applied to in-line monitor the extrusion of PLLA on a co-rotating twin screw extruder. Molar mass, viscosity and in vitro biodegradation behavior...
Polystyrene-layered silicate nanocomposites were prepared from three new organically modified clays by emulsion polymerization method. These nanocomposites were exfoliated up to 3wt% content of pristine clay relative to the amount of polystyrene (PS). The intercalated agents C 20 , C 20 –4VB, and C 20 –POSS intercalated into the galleries result in improved compatibility between...
Nucleophilic substitutions of the reactive chlorine atoms in either cyanuric or phosphonitrilic chloride by the bridging 1,4-phenylenediamine and benzidine units lead to the formation of two- (2-D) or three-dimensional (3-D) covalent networks, according to the spatial arrangement of the chlorine atoms in each particular triazine core. The materials are electrochemically active and stable, and exhibit...
Self-assembly behavior of poly(γ-benzyl l-glutamate)-graft-poly(ethylene glycol) (PBLG-g-PEG) in ethanol medium was studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), laser light scattering (LLS), and circular dichroism (CD). The experimental results revealed that the conformation change of the polypeptide graft copolymer exerts marked effect on its self-association...
In this paper, a molecular imprinted material with high performance for recognizing pirimicarb, which is a kind of carbamate pesticide, was prepared by adopting the novel surface molecular imprinting technique put forward by us previously. Firstly, the functional macromolecule poly(methacrylic acid) (PMAA) was grafted on the surface of silica gel particles in the manner of “grafting from” using 3-methacryloxypropyl...
The effect of organically modified clay on the morphology, rheology and mechanical properties of high-density polyethylene (HDPE) and polyamide 6 (PA6) blends (HDPE/PA6=75/25 parts) is studied. Virgin and filled blends were prepared by melt compounding the constituents using a twin-screw extruder. The influence of the organoclay on the morphology of the hybrid was deeply investigated by means of wide-angle...
Four high-purity aromatic diamine-based benzoxazines (13–16), which could not easily be synthesized by traditional approaches, were successfully synthesized by a facile, widely useful three-step synthetic method using four typical aromatic diamines – 4,4′-diamino diphenyl methane (1), 4,4′-diamino diphenyl sulfone (2), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (3), and bis(4-(4-aminophenoxy)phenyl)ether...
Linear 1-arm and 2-arm poly(l-lactide) [i.e., poly(l-lactic acid) (PLLA)] polymers having relatively low number-average molecular weights (M n ) (≤5×10 4 gmol −1 ) were synthesized by ring-opening polymerization of l-lactide initiated with tin(II) 2-ethylhexanoate (i.e., stannous octoate) and coinitiators of l-lactic acid, 1-dodecanol (i.e., lauryl alcohol), and ethylene glycol...
Solubilization of various polycyclic aromatic hydrocarbon (PAH) probes by arborescent polystyrene-graft-poly(2-vinylpyridine) unimolecular micelles of different structures in aqueous solutions was investigated by UV and fluorescence spectroscopies. The micelle–water partition coefficient K w and the solubilization capacity κ G both increased with the polystyrene content of the copolymers...
A novel six-membered cyclic carbonate with pendent allyl ether group, 5-allyloxy-1,3-dioxan-2-one (ATMC), was synthesized from glycerol, and the corresponding polycarbonate, poly(5-allyloxy-1,3-dioxan-2-one) (PATMC) was further synthesized by ring-opening polymerization in bulk at 120°C. Two kinds of catalyst, tin(II) 2-ethylhexanoate (Sn(Oct) 2 ) and immobilized porcine pancreas lipase on...
A nylon 6,6 complex with GaCl 3 in nitromethane (4–5wt% nylon 6,6) was prepared at 50–70°C over 24h for the purpose of disrupting the interchain hydrogen bonding between nylon 6,6 chains, resulting in amorphous nylon 6,6, and increasing the draw ratio for improving the performance of nylon 6,6 fibers. After drawing, complexed films and fibers were soaked in water to remove GaCl 3 and...
Gold nanoparticles (NPs) were prepared by reduction of HAuCl 4 in aqueous solution and stabilized by poly(N-isopropylacrylamide) (PNIPAM). PNIPAM was prepared by two distinct routes: (i) conventional free-radical polymerization leading to polymer without any reactive end-group, and (ii) Reversible Addition–Fragmentation chain Transfer (RAFT) polymerization with 2-dodecylsulfanylthiocarbonylsulfanyl-2-methyl...
Free-standing polypyrrole films have been stretched or cold rolled to produce uniaxially and biaxially textured films. The oriented films show an increase in conductivity up to 3× when compared to unprocessed films, due to polymer chain alignment. Highly anisotropic active stress and strain are observed for the textured films, with up to 7× larger active strains transverse to the orientation direction...
Submicron fibers with bactericidal properties were prepared from electrospinning of blends containing cellulose acetate (CA) as a polymer base, chlorhexidine (CHX) as a bactericidal agent, and organic titanate Tyzor ® TE (TTE) as a cross-linker. A small amount of high molecular weight poly(ethylene oxide) (PEO) was incorporated into the blends to facilitate the electrospinning, and its effect...
Computational studies were carried out to investigate the influence of polymerization procedure on the topology and various macromolecular characteristics of the highly branched polymers formed by the reaction of A 2 and B 3 type monomers through step-growth polymerization reactions. The influence of three different polymerization procedures on the properties of the polymers formed...
A series of carboxylic acid functionalized hybrid linear-dendritic block copolymers (LDBCs) derived from methoxy poly(ethylene glycol) (MPEG) and variant generation dendrons from 2,2-bis(hydroxymethyl) propionic acid were synthesized and employed as CaCO 3 crystallization growth modifiers. Mainly spherical vaterite particles of gradually reduced sizes were produced with the increase of the...
Dissipative particle dynamics method was used to study the multicompartment micelles formed from star-dendritic triblock copolymers in selective solvents, in which particular attention was paid to the effects of dendritic structure. The simulations show that the dendritic structure not only influences the morphology and the formation process of multicompartment micelles formed, but also the response...
Microfibrillated cellulose (MFC) possessing a ‘web-like’ morphology was successfully modified with three different coupling agents: 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, and a titanate coupling agent (Lica 38). The surface modification was confirmed using infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), environmental scanning electron microscopy (ESEM),...
Two series of high-performance polymer alloys were prepared by mixing typical benzoxine monomers, 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (P-a) or 6,6-(1-methylethyliden)-bis-(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine) (B-a), with a typical bismaleimide, 4,4-bismaleimidodiphenyl methane by various ratios followed by thermal treatment up to 240°C. DSC and IR of the alloys were examined to follow the...
The effects of additives of poly(methyl methacrylate) (PMMA) and HAuCl 4 on the morphologies of hybrid titania films formed via co-assembly of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymers, titania sol–gel precursor in a selective solvent were investigated. The results show that addition of PMMA or HAuCl 4 has an important influence on the morphologies of hybrid titania...
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