@article { ISI:000242468700017, title = {Development of transdermal drug-delivery films with castor-oil-based polyurethanes}, journal = {Journal of Applied Polymer Science}, volume = {103}, number = {2}, year = {2007}, month = {JAN}, pages = {779-788}, publisher = {JOHN WILEY \& SONS INC}, type = {Article}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

Two different types of polyurethanes (PUs) were prepared with castor oil, ethylene glycol, isophorene diisocyanate and castor oil, and isophoren diisocyanate and poly(ethylene glycol) (400 or 600). PU films were prepared and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and gel permeation chromatography. We prepared transdermal patches by loading different amounts of drug, plasticizer, and penetration enhancer. In vitro drug permeability through the castor-oil-based aliphatic PU patches was examined with a Keshary-Chien diffusion cell. The effect of castor oil on the film-forming properties and the effect of penetration enhancers on diffusion characteristics of indomethacin (IDM) drug through the castor-oil-based PU were investigated. Prolonged release of IDM was observed from the prepared PU patches. In vitro drug diffusion revealed that slow and prolonged release of IDM was achieved in the absence of penetration enhancers. The use of penetration enhancers showed a significant effect on drug diffusion. (c) 2006 Wiley Periodicals, Inc.

}, keywords = {castor oil, drug delivery, polyurethane, transdermal}, issn = {0021-8995}, doi = {10.1002/app.25070}, author = {Shelke, Namdev B. and Sairam, Malladi and Halligudi, Shivaraj B. and Aminabhavi, Tejraj M.} } @article { ISI:000281448900066, title = {Influence of structure of organic modifiers and polyurethane on the clay dispersion in nanocomposites via in situ polymerization}, journal = {Journal of Applied Polymer Science}, volume = {118}, number = {3}, year = {2010}, month = {NOV}, pages = {1774-1786}, publisher = {JOHN WILEY \& SONS INC}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

Influence of polyurethane (PU) structure on the nature of PU/clay nanocomposite was studied using varying amounts of trimethylol propane (TMP) as branching agent. The effect of hydroxyl groups in the modifier of organoclays on the structure of PU/clay nanocomposites was studied. Nanocomposites were characterized using wide-angle X-ray diffraction measurements (WAXD) and transmission electron microscopy (TEM). The results show that formation of completely exfoliated and well dispersed polyurethane/clay nanocomposites via in situ polymerization, is facilitated by the presence of tethering groups on the clay surface and an ability to form branched and crosslinked structures. Incorporation of long alkyl chains in addition to tethering hydroxyl groups in the modifier structure of the clay did not significantly improve the compatibility of linear PU with the clay. Intercalated thermoplastic polyurethane/clay nanocomposites, prepared using poly(caprolactone diol) as soft segment and isophorone diisocyanate and 1,4-butanediol as hard segments show increase in storage tensile moduli at temperatures before glass transition temperature when functional groups capable of chemically reacting with the growing polymer chains are present in the clay modifier. This is indicative of improved interaction of the polymer with the clay surface when the modifier has larger number of hydroxyl groups. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 1774-1786, 2010

}, keywords = {intercalation and exfoliation, Nanocomposites, organoclay, polyurethane}, issn = {0021-8995}, doi = {10.1002/app.32500}, author = {Rama, Mallikarjuna Shroff and Swaminathan, Sivaram} } @article { ISI:000279836400026, title = {Synthesis and characterization of polyurethane-grafted single-walled carbon nanotubes via click chemistry}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {10}, number = {9}, year = {2010}, month = {SEP}, pages = {5700-5707}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {

Polyurethane (PU)-grafted carbon nanotubes were synthesized by the coupling of alkyne moiety decorated single walled carbon nanotube (SWCNT) with azide moiety containing PU using Cu(I) catalyzed Huisgen [3 + 2] cycloaddition click chemistry. The azide moiety containing poly(E-caprolactone)diol was synthesized by ring-opening polymerization and further used for PU synthesis. Alkyne-functionalizion of SWCNT was completed by the reaction of p-aminophenyl propargyl ether with SWCNT using a solvent free diazotization procedure. Nuclear magnetic resonance, Fourier transform infrared, and Raman spectroscopic measurements confirmed the functionalization of SWCNT. Scanning electron microscopy and transmission electron microscopy images showed an excellent dispersion of SWCNTs, and specially debundling of SWCNTs could be observed due to polymer assisted dispersion. A quantitative grafting was successfully achieved even at high content of functional groups.

}, keywords = {Carbon nanotubes, Click chemistry, dispersion, polyurethane}, issn = {1533-4880}, doi = {10.1166/jnn.2010.2434}, author = {Rana, Sravendra and Cho, Jae Whan and Kumar, Indresh} } @article { ISI:000349401200010, title = {Porous poly(ethylene glycol)-polyurethane hydrogels as potential biomaterials}, journal = {Polymer International}, volume = {64}, number = {3}, year = {2015}, month = {MAR}, pages = {397-404}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

We report the synthesis of porous poly(ethylene glycol)-polyurethane (PEG-PU) hydrogels using PEG-4000 as a soft segment and 4,4-methylenebis(cyclohexylisocyanate) as a hard segment. The degree of swelling in the hydrogels could be controlled by varying the amount of crosslinking agent, namely 1,2,6-hexanetriol. Structural characterization of the hydrogels was performed using solid-state C-13 NMR and Fourier transform infrared spectroscopy. Wide-angle X-ray diffraction studies revealed the existence of crystalline domains of PEG and small-angle X-ray scattering studies showed the presence of lamellar microstructures. For generating a porous structure in the hydrogels, cryogenic treatment with lyophilization was used. Scanning electron microscopy and three-dimensional micro-computed tomography imaging of the hydrogels indicated the presence of interconnected pores. The mechanical strength of the hydrogels and xerogels was measured using dynamic mechanical analysis. The observed dynamic storage moduli (E) for the equilibrium swollen and dry gels were found to be 0.15 and 4.2 MPa, respectively. Interestingly, the porous PEG-PU xerogel also showed E of 5.6 MPa indicating a similar mechanical strength upon incorporating porosity into the gel matrix. Finally, preliminary cytocompatibility studies showed the ability of cells to proliferate in the hydrogels. These gels show promise for applications as scaffolds and implants in tissue engineering. (c) 2014 Society of Chemical Industry

}, keywords = {hydrogels, permeability, poly(ethylene glycol), polyurethane, porosity}, issn = {0959-8103}, doi = {10.1002/pi.4802}, author = {Divakaran, Anumon V. and Torris, Arun A. T. and Lele, Ashish K. and Badiger, Manohar V.} } @article {48386, title = {Reinforcement of electrospun polyurethane fibers with resorcinol-formaldehyde resin}, journal = {Journal of Applied Polymer Science}, volume = {139}, year = {2022}, month = {MAY}, pages = {e52007}, type = {Article}, abstract = {

This work reports a simple method to improve the properties of electrospun nanofibers. The procedure involves developing nanofibers using electrospinning followed by liquid infiltration to reinforce the fibers. Coating of polyurethane nanofibers (PUN) with resorcinol-formaldehyde (RF) significantly improves the properties of PUN. Furthermore, the morphology of fiber interface and the properties of RF coated fibers indicate that RF resin reinforces the interface between the fibers. The method leads to improvement in mechanical properties of PUN. An improvement of about 94\% and 281\% in mechanical properties like tensile strength and modulus, respectively, compared to neat PUN fibers is achieved by coating with 20\% wt/vol of RF solution.

}, keywords = {Dynamic mechanical analysis, electrospinning, liquid infiltration, polyurethane, reinforced nanofibers, resorcinol-formaldehyde}, issn = {0021-8995}, doi = {10.1002/app.52007}, author = {Nair, Kiran Sukumaran and James, Nirmala Rachel} } @article {48768, title = {Selective oxidation of 5-HMF to DFF over alkali promoted Mn nanocomposite}, journal = {Applied Catalysis A-General}, volume = {659}, year = {2023}, month = {JUN}, pages = {119180}, type = {Article}, abstract = {

Various compositions of Cs promoted Mn catalysts were synthesized and investigated for selective oxidation of 5HMF to DFF, among which Mn-Cs(80:20) was found to be most efficient giving 91 \% conversion of 5-HMF and 99 \% selectivity to DFF. Detail characterization like N2-sorption, BET surface area, TG-DTA, XRD, XPS, FE-SEM-EDX, TEM, HR-TEM, CO2-TPD, H2-TPR, O2-TPO, FTIR, Raman spectra and CH3OH-IR were done to establish structureactivity correlation. Enhanced surface area, porosity, thermal stability, dual morphologies were observed due to inclusion of Cs in Mn lattice domain which further enhanced the crystallinity, and oxygen diffusion on the surface. Mixed morphologies comprising nanoparticles (4-5 nm) and nanocubes (50-60 nm) were observed with enhanced redox potential and reduced work function due to weakening of Mn-O bonds. Significant increase in the basicity of catalyst, interfacial redox properties and lattice oxygen led to highly efficient oxidation of 5-HMF to DFF via Mars-van Krevelen mechanism at relatively milder conditions i.e. T = 90 degrees C and PO2= 200 psig. The catalyst was easily recyclable up to 7 times with minor loss in activity which was regenerated heat treatment protocol.

}, keywords = {5-HMF, Biomass, heterogeneous catalyst, polyurethane, Selective oxidation}, issn = {0926-860X}, doi = {10.1016/j.apcata.2023.119180}, author = {Solanki, Bhanupratap Singh and Roh, Hyun-Seog and V. Rode, Chandrashekhar} }