@article { ISI:000227321900006, title = {Hydrophobically modified poly(acrylic acid) using 3-pentadecylcyclohexylamine: synthesis and rheology}, journal = {Macromolecular Chemistry and Physics}, volume = {206}, number = {4}, year = {2005}, month = {FEB}, pages = {464-472}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

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.

}, keywords = {3-pentadecylcyclohexylamine (3-PDCA), hydrophobically modified polymers (HMPs), poly(acrylic acid), reversible associations, Rheology}, issn = {1022-1352}, doi = {10.1002/macp.200400392}, author = {Shedge, A. S. and Lele, Ashish K. and Wadgaonkar, P. P. and Hourdet, Dominique and Pcrrin, P. and Chassenieux, Christophe and Badiger, Manohar V.} } @article { ISI:000277423200006, title = {Hydrophobically modified poly(vinyl alcohol) using alkoxy-substituted methyl gallate: synthesis and rheology}, journal = {Journal of Polymer Science Part B-Polymer Physics}, volume = {48}, number = {10}, year = {2010}, month = {MAY}, pages = {1054-1063}, publisher = {JOHN WILEY \& SONS INC}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

Hydrophobically modified poly(vinyl alcohol) (HMPVA) polymers were synthesized by potassium t-butoxide-catalyzed reaction of PVA with methyl 3,4,5-tris(n-octyloxy) benzoate (MGC(8))/3,4,5-tris(n-dodecyloxy) benzoate (MGC(12)) and 1,3-propane sultone. The concentration of 1,3-propane sultone was kept constant at 10 mol \%. and that of MGC(8) (2, 3, and 4 mol \%)/MGC(12) (2 and 3 mol \%) was varied to obtain HMPVAs with different hydrophobic contents. The incorporation of MGC(8)/MGC(12) and 1,3-propane sultone onto HMPVA was confirmed by NMR spectroscopy. Rheological properties of aqueous solutions also confirmed the presence of hydrophobic and charged functional groups on HMPVAs. In the semidilute regime, the specific viscosity of HMPVAs followed concentration scaling that is typical of polyelectrolytes. At higher concentrations, the HMPVA solutions with 3 and 4 mol \% of MGC(8) exhibited large increase in specific viscosity. Oscillatory experiments on these solutions exhibited gel-like behavior at polymer concentrations of 40-50 g/L. Confocal microscopy images of HMPVA with 4 mol \% of MGC(8) clearly indicated the existence of microgels. The tendency of formation of microgels further increased with increasing chain length of the hydrophobe, that is, with MGC(12). These samples exhibited rheological behavior that is typical of soft solids and was therefore probed by the strain-rate frequency superposition technique reported recently in the literature. HMPVAs with improved rheological properties show potential applications as thickeners in cosmetic creams, lotions and as drug carriers in pharmaceutical formulations. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1054-1063, 2010

}, keywords = {gallic acid, hydrophobically modified poly(vinyl alcohol), Rheology, water-soluble polymers}, issn = {0887-6266}, doi = {10.1002/polb.21995}, author = {Shedge, Aarti S. and Wadgaonkar, Prakash P. and Lele, Ashish K. and Badiger, Manohar V.} } @article { ISI:000346263800042, title = {Synthesis and characterization of PEPO grafted carboxymethyl guar and carboxymethyl tamarind as new thermo-associating polymers}, journal = {Carbohydrate Polymers}, volume = {117}, year = {2015}, month = {MAR}, pages = {331-338}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

New thermo associating polymers were designed and synthesized by grafting amino terminated poly(ethylene oxide-co-propylene oxide) (PEPO) onto carboxymethyl guar (CMG) and carboxymethyl tamarind (CMT). The grafting was performed by coupling reaction between-NH2 groups of PEPO and -COOH groups of CMG and CMT using water-soluble EDC/NHS as coupling agents. The grafting efficiency and the temperature of thermo-association, T-assoc in the copolymer were studied by NMR spectroscopy. The graft copolymers, CMG-g-PEPO and CMT-g-PEPO exhibited interesting thermo-associating behavior which was evidenced by the detailed rheological and fluorescence measurements. The visco-elastic properties (storage modulus, G{\textquoteright}; loss modulus, G{\textquoteright}{\textquoteright}) of the copolymer solutions were investigated using oscillatory shear experiments. The influence of salt and surfactant on the T-assoc was also studied by rheology, where the phenomenon of {\textquoteleft}{\textquoteleft}Salting out{\textquoteright}{\textquoteright} and {\textquoteleft}{\textquoteleft}Salting in{\textquoteright}{\textquoteright} was observed for salt and surfactant, respectively, which can give an easy access to tunable properties of these copolymers. These thermo-associating polymers with biodegradable nature of CMG and CMT can have potential applications as smart injectables in controlled release technology and as thickeners in cosmetics and pharmaceutical formulations. (C) 2014 Elsevier Ltd. All rights reserved.

}, keywords = {Carboxymethyl guar, Carboxymethyl tamarind, Pluronics, Rheology, Solution behavior, Thermo-associating polymers}, issn = {0144-8617}, doi = {10.1016/j.carbpol.2014.09.073}, author = {Gupta, Nivika R. and Torris, Arun A. T. and Wadgaonkar, Prakash P. and Rajamohanan, P. R. and Ducouret, Guylaine and Hourdet, Dominique and Creton, Costantino and Badiger, Manohar V.} } @article {44480, title = {Thermo thickening behavior of MPEG-b-PCL grafted poly(acrylic acid): a molecular insight}, journal = {Polymer}, volume = {148}, year = {2018}, month = {JUL}, pages = {138-148}, type = {Journal Article}, abstract = {

We report on the synthesis and characterization of a new thermothickening polymer (PAA-g-(MPEG-b-PCL)) based on the grafting of a block copolymer of mono methoxy poly (ethylene glycol){\textendash}b-poly (caprolactone) (MPEG-b-PCL) onto poly (acrylic acid) (PAA). Rheological experiments reveal that aqueous solutions of PAA-g-(MPEG-b-PCL) exhibit interesting irreversible thermothickening behavior above a certain polymer concentration and critical temperature. Light scattering experiments show that increasing temperature induces hydrophobic associations and subsequent aggregation leading to gel formation which is irreversible. The mechanism of thermo thickening was examined at the molecular level by NMR methods which indicated unassembled and assembled environments of the MPEG-b-PCL grafts. On heating, interactions between the graft side chains are significantly enhanced and molecular mobility in the assembled microdomains is reduced. The stable well ordered microdomains that are formed on heating are retained on cooling thus, leading to irreversible gelation.

}, keywords = {Hydrophobically modified poly (acrylic acid), Light scattering, Methoxy polyethylene glycol-b-polycaprolactone (MPEG-b-PCL) copolymer, Rheology, Thermo gelation}, issn = {323861}, doi = {10.1016/j.polymer.2018.06.031}, author = {Tiwari, Neha}, editor = {Shedge, Aarti} }