02214nas a2200277   4500008004100000022001400041245010600055210006900161260007700230300001200307490000800319520117400327653004101501653004501542653002301587653002801610653001301638100001901651700002101670700002301691700002301714700001501737700002801752700002501780856013101805       2005                        eng d  a1022-135200aHydrophobically modified poly(acrylic acid) using 3-pentadecylcyclohexylamine: synthesis and rheology0 aHydrophobically modified polyacrylic acid using 3pentadecylcyclo  aPO BOX 10 11 61, D-69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcFEB  a464-4720 v2063 a<p>Hydrophobically modified poly(acrylic acid) was synthesized using 3-pentadecylcyclohexylamine (3-PDCA), which was in turn synthesized from 3-pentadecylphenol, one of the components of cashew-nut shell liquid (CNSL), a renewable resource material. H-1 NMR spectra confirmed the incorporation of 3-PDCA onto PAA and a series of HMPs with three different molar concentrations, viz. congruent to 3, 5 and 7 mol-% of 3-PDCA, were synthesized. An increase in viscosity with increasing hydrophobic content was observed by rheological measurements. The critical association concentrations were determined using an Ubbelohde viscometer and a controlled stress rheometer. The stability of HMPs towards temperature and shear was studied. Rheological measurements showed that there was a steady increase in viscosity with increase in hydrophobe content due to the formation of reversible networks. These polymers exhibited gel-like behavior at low concentrations (greater than or equal to2 wt.-%) with an apparent yield stress (ca. 10 Pa) and showed shear thinning properties (non-Newtonian). However, below a critical concentration, c [eta], they showed Newtonian behavior.</p>10a3-pentadecylcyclohexylamine (3-PDCA)10ahydrophobically modified polymers (HMPs)10apoly(acrylic acid)10areversible associations10aRheology1 aShedge, A., S.1 aLele, Ashish, K.1 aWadgaonkar, P., P.1 aHourdet, Dominique1 aPcrrin, P.1 aChassenieux, Christophe1 aBadiger, Manohar, V.  uhttps://library.ncl.res.in/content/hydrophobically-modified-polyacrylic-acid-using-3-pentadecylcyclohexylamine-synthesis-and-102166nas a2200241   4500008004100000022001400041245011300055210006900168260009900237300001600336490000700352520124300359653002501602653002301627653001501650100001701665700002301682700002501705700002801730700001501758700001901773856013201792       2005                        eng d  a0032-386100aSynthesis and swelling behaviour of hydrophobically modified responsive polymers in dilute aqueous solutions0 aSynthesis and swelling behaviour of hydrophobically modified res  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcDEC  a12190-121990 v463 a<p>New series of associating polymers were synthesised in order to investigate opposite behaviours of hydrophobically modified water-soluble polymers and thermoresponsive water-soluble polymers carrying LCST stickers. On the basis of a poly(acrylic acid) backbone, amino-terminated poly(N-isopropylacrylamide), poly(ethylene oxide-co-propylene oxide) and/or dodecyl chains were grafted following a reaction of condensation activated by carbodiimide. Two homologous series of well-defined single grafted and double grafted copolymers were obtained, with double grafted chains containing both C12 and LCST grafts. The dilute solution properties of these copolymers were carefully studied by capillary viscometry. At low salt concentration and below the LCST of the grafts, the swelling properties of macromolecular chains are controlled either by intramolecular associations between hydrophobes, excluded volume effect exerted by hydrophilic grafts or by a balance between these opposite interactions. The deswelling of macromolecular chains, induced by hydrophobic interactions, is amplified at higher ionic strength and more particularly above the transition temperature of the side chains. (c) 2005 Elsevier Ltd. All rights reserved.</p>10aassociating polymers10apoly(acrylic acid)10aviscometry1 aIyer, N., P.1 aHourdet, Dominique1 aBadiger, Manohar, V.1 aChassenieux, Christophe1 aPerrin, P.1 aWadgaonkar, P.  uhttps://library.ncl.res.in/content/synthesis-and-swelling-behaviour-hydrophobically-modified-responsive-polymers-dilute-aqueous01589nas a2200289   4500008004100000020002200041022001400063245004500077210004500122260010600167300001200273490000900285520068300294653002900977653001301006653002101019100002401040700002101064700002801085700001801113700002201131700001101153700001701164700001801181700002101199856007901220       2008                        eng d  a978-0-7354-0549-3  a0094-243X00aGelation of regenerated fibroin solution0 aGelation of regenerated fibroin solution  aMonterey, CA.bAmer Inst Physics, 2 Huntington Quadrangle, STE 1NO1, Melville, NY 11747-4501 USAcAUG  a573-5750 v10273 a<p>Silk fibroin is a high molecular weight multiblock ampiphillic protein known for its ability to form high strength fibers. It is also biocompatible; silk sutures have been traditionally used for many centuries. Recently, there has been much interest in making silk hydrogels for applications ranging from tissue engineering to controlled delivery. Fibroin gels can be formed from aqueous solutions by changing one or more state variables such as pH, temperature and ionic strength. In this work we present our investigations on the gelation of aqueous fibroin solutions derived from Bombyx Mori silk using light scattering, confocal microscopy and rheological techniques.</p>10adynamic light scattering10aRheology10asilk fibroin gel1 aNagarkara, Shailesh1 aLele, Ashish, K.1 aChassenieux, Christophe1 aNicolai, Taco1 aDurand, Dominique1 aCo, A.1 aLeal, L., G.1 aColby, R., H.1 aGiacomin, A., J.  uhttps://library.ncl.res.in/content/gelation-regenerated-fibroin-solution-102531nas a2200193   4500008004100000022001400041245012400055210006900179260007100248300001600319490000700335520176400342100002102106700001802127700002502145700002402170700002802194856011502222       2010                        eng d  a0024-929700aAbrupt shear thickening of aqueous solutions of hydrophobically modified poly(N,N `-dimethylacrylamide-co-acrylic acid)0 aAbrupt shear thickening of aqueous solutions of hydrophobically   a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcDEC  a10055-100630 v433 a<p>We report some new and interesting observations on the abrupt and large shear-induced thickening of aqueous solutions of hydrophobically modified poly(N,N'-dimethylacrylamide-co-acrylic acid). High molecular weight copolymer was prepared by free radical copolymerization of N,N'-dimethylacrylamide [DMA] and acrylic acid [AA] and was subsequently modified to different extents using a hydrophobic compound, namely, 3-pentadecylcyclohexylamine [3-PDCA], which is derived from a renewable resource material, cashew nutshell liquid [CNSL]. The structural elucidation of the base copolymer and the hydrophobically modified copolymers was performed by (1)H and (13)C NMR spectroscopy. The zero shear viscosities [eta(0)] of the hydrophobically modified polymers were lower than that of the precursor poly(N,N'-dimethylacrylamide-co-acrylic acid) until some critical polymer concentration, which increased with increase in hydrophobic modification. Above the critical concentrations, the eta(0) of the hydrophobically modified copolymers surpassed that of the precursor at the same concentration. At moderate shear rates some of these hydrophobically modified copolymers exhibited an abrupt shear-induced thickening in which the viscosity of the samples increased severalfold. We show here from creep experiments that thickening occurs only when the shear rate reaches a critical value, (gamma) over dot(crit), and that the thickened samples can be trapped in different metastable states by controlling the applied stress. Interestingly, the shear thickened samples showed further thickening upon decreasing the applied stress. Eventually, the metastable samples revert to their equilibrium states at characteristic time that depends on (small) probe stress.</p>1 aLele, Ashish, K.1 aShedge, Aarti1 aBadiger, Manohar, V.1 aWadgaonkar, Prakash1 aChassenieux, Christophe  uhttps://library.ncl.res.in/content/abrupt-shear-thickening-aqueous-solutions-hydrophobically-modified-polynn-001761nas a2200181   4500008004100000022001400041245005500055210005500110260011000165300001400275490000700289520110400296100002301400700001801423700002801441700002101469856008901490       2010                        eng d  a1463-907600aStructure and gelation mechanism of silk hydrogels0 aStructure and gelation mechanism of silk hydrogels  aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcFEB  a3834-38440 v123 a<p>Silk fibroin was regenerated from cocoons produced by the silkworm Bombyx Mori. Light scattering showed that an aqueous solution of the regenerated silk fibroin (RSF) was made of individual proteins with a weight average molar mass of about 4 x 10(5) g mol(-1) and a hydrodynamic radius of about 10 nm. Gel formation of RSF in acidic solutions was investigated as a function of the pH (2-4), concentration (0.5-10 g L(-1)) and temperature (5-70 degrees C). The structure of the gels was studied using light scattering and confocal laser scanning microscopy. The structure was found to be self-similar from length scales of less than 15 nm up to length scales of about 1 mm, and characterized by a correlation length of a few microns. Gel formation was tracked using turbidity, rheology, light scattering and circular dichroism. Gelation involves the formation of self-similar aggregates with a growth rate that increases exponentially. The protein aggregation is correlated to, and perhaps caused by, the formation of beta-sheets, the fraction of which also increases exponentially with time.</p>1 aNagarkar, Shailesh1 aNicolai, Taco1 aChassenieux, Christophe1 aLele, Ashish, K.  uhttps://library.ncl.res.in/content/structure-and-gelation-mechanism-silk-hydrogels-0