نتایج جستجو برای: copolymer
تعداد نتایج: 12139 فیلتر نتایج به سال:
Production of novel polyhydroxyalkanoates (PHAs), biodegradable polymers for biomedical applications, and biomaterials based on them is a promising trend in modern bioengineering. We studied the ability of an effective strain-producer Azotobacter chroococcum 7B to synthesize not only poly(3-hydroxybutyrate) homopolymer (PHB) and its main copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P...
We present results of Monte Carlo simulation studies utilizing the bond fluctuation model in conjunction with single and configurational biased Monte Carlo moves to investigate the adsorption of diblock ~A–b–B! and alternating ~A–alt–B! copolymers at physically flat surfaces made of an equal number of two chemically different sites, C and D. The adsorption of the copolymer to the surface is dri...
This work proposes a new method for Co(II) determination based on the use of the triblock copolymer as micellar medium instead of chloroform. The proposed strategy is environmental friendly because the copolymer is biodegradable and nontoxic. The method is based on the formation of a cobalt-1-nitroso-2-naphthol complex, in the micellar triblock copolymer compound solution constituted by polyeth...
A copolymer of dodecyl methacrylate/styrene (DMA/St) containing the amidine functionality was synthesized and characterized. The one-step solution copolymerization process was carried out using a mixed solvent, high temperature, and a functional azo initiator, 2,2 -azobis[N,N -dimethylene isobutyramidine]. Copolymers with different compositions (DMA/St 10/1 to 1/2), molecular weight (Mn 2000–90...
A novel biodegradable amphiphilic copolymer composed of hydroxypropyl-β-cyclodextrin, polylactide, and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, was successfully synthesized. The chemical structures of copolymers were determined by FT-IR, (1)H nuclear magnetic resonance (NMR) spectroscopy, (13)C NMR, (31)P NMR, thermogravimetric analysis ,and differential scanning calorimetry. Doxorubic...
Electrical field-induced strain response of electron-irradiated poly~vinylidene fluoride-trifluoroethylene! copolymer has been studied by a Mach–Zehnder type heterodyne interferometer in the frequency range of 3–9 kHz. The electrostrictive constant is calculated from the strain results, which is of the same order of magnitude as those obtained at 1 Hz by a bimorph-based strain sensor but at muc...
Next generation photoresist systems using block copolymer self-assembly have been developed and characterized within the Ober Research Group. Block copolymers containing methacrylate polymer backbones have been designed for low absorption in 193 nm lithography. The polymers synthesized are composed of two polymer chains that can be selectively crosslinked or removed, respectively, from the poly...
Incorporation of nanoparticles composed of surface-functionalized fumed silica (FS) or native colloidal silica (CS) into a nanostructured block copolymer yields hybrid nanocomposites whose mechanical properties can be tuned by nanoparticle concentration and surface chemistry. In this work, dynamic rheology is used to probe the frequency and thermal responses of nanocomposites composed of a symm...
Graft copolymerization of rosin-(2-acryloyloxy)ethyl ester (RAEE) onto chitosan (Cts) was carried out under microwave irradiation using potassium persulfate as an initiator. The structures, morphology, and thermal properties of the Cts graft copolymer (Cts-g-PRAEE) were characterized by means of FT-IR, XRD, SEM, and TG. Also, Cts and Cts-g-PRAEE copolymer were used as carriers of fenoprofen cal...
For many years, copolymerization has been studied using mathematical and statistical models. Here, we present new Markov chain models for copolymerization kinetics: the Bernoulli and Geometric models. They model copolymer synthesis as a random process and are based on a basic reaction scheme. In contrast to previous Markov chain approaches to copolymerization, both models take variable chain le...
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