Biocompatible Polymer Blends of Poly(D,L-lactic acid-co-glycolic acid) and Triblock PCL-PDMS-PCL Copolymers: Their Characterizations and Degradations

Polymer blends of poly(D,L-lactic-co-glycolic acid), PDLLGA, and triblock polycaprolactonepoly(dimethylsiloxane)-polycaprolactone (PCL-PDMS-PCL) copolymer, TEGOMER, were obtained by coprecipitation from their chloroform mixed solutions into methanol and were characterized by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), degradation tests and scanning electron microscopy (SEM). Binary blends of PDLLGA/TEGOMER were found to be partially miscible according to DSC measurements and FTIR analysis. Stressstrain results showed that addition of TEGOMER improved significantly the overall toughness of PDLLGA. Degradation of PDLLGA/TEGOMER blends was investigated in phosphate buffered saline at pH = 7.4 and 37 °C, and the morphology of the blends during degradation was examined by scanning electron microscopy

Biocompatible Polymer Blends of Poly(D,L-lactic acid-co-glycolic acid) and Triblock PCL-PDMS-PCL Copolymers: Their Characterizations and Degradations

Polymer blends of poly(D,L-lactic-co-glycolic acid), PDLLGA, and triblock polycaprolactonepoly(dimethylsiloxane)-polycaprolactone (PCL-PDMS-PCL) copolymer, TEGOMER, were obtained by coprecipitation from their chloroform mixed solutions into methanol and were characterized by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), degradation tests and scanning electron microscopy (SEM). Binary blends of PDLLGA/TEGOMER were found to be partially miscible according to DSC measurements and FTIR analysis. Stressstrain results showed that addition of TEGOMER improved significantly the overall toughness of PDLLGA. Degradation of PDLLGA/TEGOMER blends was investigated in phosphate buffered saline at pH = 7.4 and 37 °C, and the morphology of the blends during degradation was examined by scanning electron microscopy

Nonisocyanate based polyurethane/silica nanocomposites and their coating performance

A series of silica nano-particles with different size were prepared by sol–gel technique, then surface modification by using cyclic carbonate functional organoalkoxysilane (CPS) was performed. Various amounts of carbonated silica particles directly added into carbonated soybean oil (CSBO) and carbonated polypropylene glycol (CPPG) resin mixture to prepare polyurethane–silica nanocomposite coating compositions by nonisocyanate route using an aliphatic diamine as a curing agent. Cupping, gloss, impact, and taber abrasion tests were performed on aluminum panels coated with those nano-composite formulations and tensile tests, thermogravimetric and SEM analyses were conducted on the free films prepared from the same coating formulations. An increase in abrasion resistance of CSBO-CPPG resin combination with the addition of silica was observed. In addition, the maximum weight loss of CSBO-CPPG resin combination was shifted to higher temperatures with incorporation of silica nano-particles The positive effect of modified silica particles on thermal stability of CSBO-CPPG system could be explained in such a way that PPG chains are able to disperse particles in the medium throughout the interactions between ether linkages and silanol groups

Anticancer drug release from poly(N-isopropylacrylamide/itaconic acid) copolymeric hydrogels

The drug uptake and release of anticancer drug from N-isopropylacrylamide/itaconic acid copolymeric hydrogels containing 0-3 mol% of itaconic acid irradiated at 48 kGy have been investigated. 5-Fluorouracil (5-FU) is used as a model anticancer drug. The effect of 5-FU solution on swelling characteristics of PNIPAArn and P(NIPAAm/IA) copolymeric hydrogels have also been studied. The percent swelling, equilibrium swelling, equilibrium water/5-FU content and diffusion constant values are evaluated for poly(N-isopropylacrylamide) (PNIPAAm) and poly(N-isopropylacrylamide/itaconic) (P(NIPAAm/IA)) hydrogels at 130 ppm of 5-FU solution at room temperature. Diffusion of 5-FU solution into the hydrogels has been found to be the non-Fickian type. Finally, the kinetics of drug release from the hydrogels are examined. (c) 2004 Elsevier Ltd. All rights reserved

Synthesis and characterization of pendant carboxylic acid functional poly(lactic acid) and poly(lactic acid-co-glycolic acid) and their drug release behaviors

The carboxylic acid functionalized biodegradable aliphatic polyesters were prepared by ring-opening polymerization of L-lactide and glycolide with 2,2'-bis(hydroxymethyl propionic acid) (HMPA) as an initiator. The polymers were characterized by FT-IR, H-1-NMR and gel permeation chromatography (GPC). Molecular weights of homopolymers and copolymers ranged from 0.28 X 10(4) to 11 X 10(4) and decreased with increasing weight fraction of HMPA in the feed. Moreover by changing the HMPA content, the solubility and degradation behavior of resulting polymers could be varied. Environmental scanning electron microscopy (ESEM) studies revealed that the microspheres were spherical in shape and had a smooth surface texture. For the investigation of drug release behavior of biopolymers, Lidocain was used as a model ionic drug. It was observed that an increase in drug loading reduces the encapsulation efficiency. After the initial burst, the release rate of the drug increased with time, with most of the drug released within 15 days. Copyright (c) 2005 John Wiley & Sons, Ltd

Preparation, characterization and drug release behavior of poly(acrylic acid-co-2-hydroxyethyl methacrylate-co-2-acrylamido-2-methyl-1-propanesulfonic acid) microgels

In this paper, Poly(acrylic acid-co-2-hydroxyethyl methacrylate-co-2-acrylamido-2-methyl-1-propanesulfonic acid (AAc-HEMA-AMPS) microgels were synthesized by using an inverse suspension polymerization technique. The increase in the AMPS content of the microgels composition caused a large increase in water uptake. The morphology of the microgels was examined by environmental scanning electron microscopy (ESEM). The AMPS containing microgels had a mean particle diameter of 10 mu m. The glass transition temperature of the microgels were examined by DSC and found that they show single Tg. Lidocaine (LD) and Methylene blue (MB) were used as model drugs for the investigation of drug release behavior of the microgels. Different drug release patterns were observed, for LD and MB loaded microgels. The release studies showed that some of the basic parameters affecting the drug release behavior of microgels were the specific and non-specific interactions between microgel and drug structure and pH of the dissolution medium. These hydrogels may be potential candidates for pH-sensitive applications

Naphthalene-based polyimide electrolytes for lithium-ion battery applications

The preparation of 2,6-Bis(m-amino phenoxy) benzoyl naphthalene-based polyimides for solid polymer electrolytes was reported. Li-salt and PEO bearing polyimide membranes were prepared. Thermo-gravimetric analysis results reveal that the PI/PEO/LiCF3SO3 polymer electrolyte membranes are thermally stable up to 500 degrees C. The T-g values are in the range 167-221.5 degrees C according to dynamic mechanical analysis (DMA). The conductivities of Li-salt and PEO containing PI membranes are in the range of 10(-7)-10(-5)S/cm. The conductivity increases with incorporation of PEO and Li+ concentration. The linear sweep voltammetry experiments showed that no peaks were observed between 1.75 and 4.5V

Preparation of poly (N-isopropylacrylamide/itaconic acid) copolymeric hydrogels and their drug release behavior

N-isopropylacrylamide/itaconic acid copolymeric hydrogels were prepared by irradiation of the ternary mixtures of N-isopropylacrylamide/itaconic acid/water by gamma-rays at ambient temperature. The effect of comonomer concentration, irradiation dose and pH on the swelling equilibria were studied. Lidocaine was used as a model drug for the investigation of drug release behaviour of hydrogels. Lidocaine adsorption capacity of the hydrogels were found to increase from 3.6 to 862.1 (mg lidocame/g dry gel) with increasing amount of itaconic acid in the gel structure. Adsorption and release processes were followed at 4 and 37 degreesC, respectively. The release studies showed that the basic parameters affecting the drug release behaviour of the hydrogels were pH and temperature of the solution and cross-link density of the gels. (C) 2004 Elsevier B.V. All rights reserved

Preparation and characterization of sol-gel derived UV-curable organo-silica-titania hybrid coatings

In this work, UV-curable organic-inorganic hybrid coatings based on cycloaliphatic epoxyacrylate were prepared by sol-gel technique. Acid catalyzed solutions of tetraethylorthosilane (TEOS) containing Ti:acac complex were used as an inorganic precursors. UV-curable, transparent hybrid coating materials were applied on plexiglass substrates and their coating performance was investigated by the analyses of various tests such as hardness, gloss, cross-cut adhesion tests, stress-strain test and optical transmission. The mechanical measurements showed that, the tensile properties of coatings underwent an abrupt change from a brittle to a tough material when the inorganic part was incorporated into the cycloaliphatic epoxy acrylate based organic network. UV-vis transmission spectroscopy results indicated that the hybrid materials with high titanium content have good transparences. The thermal behaviour of the coatings was also evaluated. It is observed that the thermal stability of the hybrids is enhanced with incorporation of sol-gel precursor. (c) 2007 Elsevier B.V. All rights reserved

pH-thermoreversible hydrogels. I. Synthesis and characterization of poly(N-isopropylacrylamide/maleic acid) copolymeric hydrogels

N-isopropylacrylamide (NIPAAM)/maleic acid (MA) copolymeric hydrogels were prepared by irradiating the ternary mixtures of NIPAAM/MA/Water by gamma-rays at ambient temperature. The influence of external stimuli such as pH and temperature of the swelling media on the equilibrium swelling properties was investigated. The hydrogels showed both temperature and pH responses. The effect of comonomer concentration and irradiation dose on the swelling equilibria and phase transition was studied. For the characterization of these hydrogels, the diffusion behaviour and molecular weight between crosslinks were investigated. (C) 2003 Elsevier Ltd. All rights reserved