Diethylene Glycol Bis Allyl Carbonate Research Articles

Arginine functionalization of hydrogels for heparin binding—a supramolecular approach to developing a pro‐angiogenic biomaterial

Our aim was to synthesize a biomaterial that stimulates angiogenesis for tissue engineering applications by exploiting the ability of heparin to bind and release vascular endothelial growth factor (VEGF). The approach adopted involved modification of a hydrogel with positively charged peptides (oligolysine or oligoarginine) to achieve heparin binding. Precursor hydrogels were produced from copolymerization of N-vinyl pyrolidone, diethylene glycol bis allyl carbonate and acrylic acid (PNDA) and functionalized after activation of the carboxylic acid groups with trilysine or triarginine peptides (PNDKKK and PNDRRR). Both hydrogels were shown to bind and release bioactive VEGF165 with arginine-modified hydrogel outperforming the lysine-modified hydrogel. Cytocompatibility of the hydrogels was confirmed in vitro with primary human dermal fibroblasts and human dermal microvascular endothelial cells (HUDMECs). Proliferation of HUDMECs was stimulated by triarginine-functionalized hydrogels, and to a lesser extent by lysine functionalized hydrogels once loaded with heparin and VEGF. The data suggests that heparin-binding hydrogels provide a promising approach to a pro-angiogenic biomaterial.

Estimation of track registration efficiency in solution medium and study of gamma irradiation effects on the bulk-etch rate and the activation energy for bulk etching of CR-39 (DOP) solid state nuclear track detector

The fission track registration efficiency of diethylene glycol bis allyl carbonate (dioctyl phthalate doped) [CR-39 (DOP)] solid state nuclear track detector (SSNTD) in solution medium (Kwet) has been experimentally determined and is found to be (9.7 ± 0.5) × 10−4 cm. This is in good agreement with the values of other SSNTDs. The gamma irradiation effects in the dose range of 50.0–220.0 kGy on the bulk etch rate, Vb and the activation energy for bulk etching, E of this solid state nuclear track detector (SSNTD) have also been studied. It is observed that the bulk etch rates increase and the activation energies for bulk etching decrease with the increase in gamma dose. These results have been explained on the basis of scission of the detector due to gamma irradiation.

Novel way of making high refractive index plastics; metal containing polymers for optical applications

AbstractPlastics are being preferred in almost all possible applications of materials. Several new applications including optical devices are being developed using plastics replacing conventional materials like inorganic glass etc. For the optical applications, the most important properties of plastics essential for their desired performance include refractive index, Abbe number, optical clarity, etc. The biggest challenge in developing suitable materials for optical applications has always been to meet the criteria of high refractive index along with a high Abbe number. Normally, if the refractive index increases, the Abbe number automatically decreases. The researchers have tried several approaches to deal with this typical challenge without which it is not possible to develop novel optical plastics. Presently the most popularly known optical plastics includes polymers such as polymethacrylates, polyurethanes, polycarbonates, polystyrene and diethylene glycol bis allyl carbonate. The latest material of high refractive index plastics with a refractive index of 1.67 belongs to the polythiourethanes chemistry. Several approaches are being tried world over, to develop materials of high refractive index. One of the approaches being pursued for enhancement of refractive index of existing monomers pertain to the incorporation of metals or metal salts in the matrices. The other commonly tried but difficult to achieve approaches pertain to the preparation of nanoparticles or nanocomposites.

Neutron-irradiation effects on track etching and optical characteristics of CR-39 (DOP) nuclear track detector

The effects of thermal neutron-irradiation in the neutron fluence range of (1.77–7.08) 1011 n/cm2, on the etching and optical characteristics of diethylene glycol bis allyl carbonate (dioctyl phthalate doped), CR-39 (DOP) nuclear track detector have been studied using etching and UV–visible spectroscopic techniques. The bulk etch rates determined at different fluences were found to increase with an increase in neutron fluence up to 3.54 × 1011 n/cm2, and then decrease at higher neutron fluence. The optical absorption spectra in the wavelength range of 200–800 nm were also recorded for the unirradiated and neutron irradiated samples in the above fluence range. The optical energy gaps (E g) were determined by the shift in optical absorption edges as observed by UV–visible spectra of the neutron irradiated sample, using Tauc’s expression. The UV–visible spectra results were further supported by determining the activation energies for bulk etching.

Examination of the effects of poly( N-vinylpyrrolidinone) hydrogels in direct and indirect contact with cells

Poly( N-vinylpyrrolidinone) (PNVP) has been used in various biomedical applications for many years. This study explores two PNVP hydrogels for their biocompatibility with skin cells and their ability to support the growth of skin cells in direct and indirect contact with the cells. Two crosslinked PNVP's were investigated, one crosslinked with ethylene glycol dimethacrylate (EGDMA) and the other crosslinked with diethylene glycol bisallylcarbonate (DEGBAC). The different crosslinkers lead to hydrogels with different mechanical and slightly different biological properties. While neither hydrogel proved to be a suitable substrate for culturing cells (based on fibroblasts and a range of other cells), indirect contact with both showed them to be biocompatible and even stimulatory to fibroblasts. The P(NVP-co-DEGBAC) hydrogel stimulated fibroblast viability more reliably than the P(NVP-co-EGDMA) hydrogel when in indirect contact with cells. This effect was shown to be independent of the presence of foetal calf serum in the culture media, and could not be explained by any hydrogel breakdown products during the course of these experiments. Rather the phenomenon was observed to be the result of a dynamic interaction between the hydrogels and the cells.

Kinetics and modeling of diethylene glycol bisallyl carbonate bulk polymerization

AbstractThe free‐radical polymerization kinetics of diethylene glycol bisallyl carbonate in bulk were investigated with Fourier transform infrared and Fourier transform Raman techniques in a wide temperature range of 50–140°C with four different peroxide initiators. In addition, the ratios of the degradative kinetic rate constant to the propagation rate constant under different reaction conditions were obtained from molecular weight measurements under various reaction conditions. The ratio of the chemically controlled termination and propagation rate constants of the polymerization system were obtained with the initial rates of polymerization and the number‐average molecular weight data, which were between 8.22 × 10−5 and 1.47 × 10−3 L mol−1 s−1. The initiator efficiencies were evaluated with special experiments at low initiator concentrations with the theory of dead‐end polymerization. The computed conversions from the developed kinetic model were in good agreement with the conversion and molecular weight measured data. The values of the diffusion‐controlled propagation and termination rate constants, with clear and physical meaning, were the only two parameters obtained from the developed kinetic model fitting the measured conversion points. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 345–357, 2005

Electron microscopy of macroporous cellulose (acetate?co?butyrate)?polycarbonate semi?interpenetrating networks

Summary Semi–interpenetrating polymer networks, s–IPNs, were prepared from cellulose acetate–co–butyrate (CAB), still containing 46% OH groups, and diethylene glycol bis allylcarbonate (CR39) which was crosslinked by free–radical polymerization initiated by benzoyl peroxide. Microstructure of s–IPNs (CAB/CR39) of relative weight proportions between 0.2/1 and 0.411 was examined by electron microscopy (TEM and SEM). Spheroidal compact objects of several µm diameter are randomly distributed within a microporous phase in which the pore connectivity was shown by density measurements. Such a microstructure is consistent with the formation of CAB polymer dispersed phase in a poly (CR39) network continuous phase.

Polycarbonate particles and dye‐labeled particles by miniemulsion polymerization

AbstractWe describe the synthesis of several different polycarbonate particles by miniemulsion polymerization. The monomers were allylmethyl carbonate (AlMeC), di(ethylene glycol) bisallylcarbonate (DBAC), and 4‐vinyl‐1,3‐dioxan‐2‐one [vinyl ethylene carbonate (VEC)]. For these polymerizations, higher monomer conversions were obtained with oil‐soluble initiators (azobisisobutyronitrile and benzoyl peroxide) than with a water‐soluble initiator (potassium persulfate). Benzoyl peroxide was particularly effective in yielding particles with a narrow size distribution. Although increasing amounts of a surfactant (sodium dodecyl sulfate) led to smaller particles, the choice of the monomer was the major determinant. For example, in polymerization reactions carried out at 85 °C with benzoyl peroxide as the initiator and with otherwise identical recipes, we obtained particle sizes of 181 nm with AlMeC, 296 nm with VEC, and 203 nm with DBAC. Fluorescent particles were synthesized with comonomers based on the benzothioxanthene nucleus. Because the dyes had poor solubility in the monomers, it was necessary to include typically 20 wt % bromobenzene or dichlorobenzene based on the monomer in the miniemulsion reaction mixture. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1999–2009, 2004

Strain-rate effects on hardness of glassy polymers in the nanoscale range. Comparison between quasi-static and continuous stiffness measurements

Strain rate effects on Hardness and Young's modulus of two glassy polymers, poly(diethylene glycol bis allyl carbonate) (CR39) and bisphenol-A polycarbonate (PC), were studied in the nanoscale range. Before analyzing material behaviors, we focused on a particular phenomenon prevailing at the first stage of the contact between the surface of these polymers and the Berkovitch diamond tip used in the experiments, leading to an apparent increase of the tip defect (i.e., the missing tip of the diamond from having a shape equivalent to a perfect cone). The common methods based on calibration functions of the tip appear to be inaccurate to calculate correctly the contact area at the nanoscale range for these polymers. A new method based on Loubet et al.'s model to calculate the contact area by taking account of the apparent tip defect is proposed. The hardness values obtained this way were compared to the compressive yield stress using Tabor's relationship. A hardness-yield stress ratio close to 2.0, as expected on such polymers, was found. A strain-rate effect on the load-depth curve for these two polymers is interpreted as an increase of the hardness with the strain rate. The results from quasi-static and dynamic (the continuous stiffness method) measurements are compared. The strain-rate effect on Young's modulus in dynamic conditions should be taken into account in the hardness calculation.

Polymerisation of diethylene glycol bis-allyl carbonate up to high degrees of conversion

The polymerisation of diethylene glycolbis-allyl carbonate to high conversion was investigated by ESR, FTIR and DMA techniques. The ESR spectrum was simulated using a two line, a three line and a broad line spectral component. These spectral components were assigned to the propagating radical, a mobile allyl radical and a less mobile allyl radical formed on a crosslink. The change in the resonance frequency of the ESR cavity during polymerisation was demonstrated to be sensitive to gel formation. ESR and FTIR data show that the restriction in the mobility of the system occurred well after gel formation making this system different from the vinyl systems. The ESR and FTIR data were used to calculate the rate constants for propagation, termination, transfer and reinitiation at high conversion. The chain transfer constant was not found to change with conversion. The DMA data shows that the extent of cyclisation during the polymerisation is about 20–25%.

Casting of organic glass by radiation-induced polymerization of glass-forming monomers at low temperatures. V. Casting and polymer properties of CR-39 modified monomer systems

Glassification, cast polymerization, and physical properties of monomeric system including diethylene-glycolbisallyl carbonate (CR-39) was investigated. Addition of other monomers CR-39 was investigated CR39- polyfunctional monomer and CR-39-methyl methacrylate-polyfunctional monomer systems were found to form stable glassy state applicable to radiation-induced casting and good in physical property. Two-step polymerization method consisting of pre-irradiation and post-catalytic polymerization necessary to complete casting. It was found that these newly found CR-39 modified systems could be casted efficiently in much shorter time cycle than catalytic process without forming optical strain. Physical properties of casted polymer such as impact resistance and heat durability were sufficient for practical use.