02512nas a2200241 4500008004100000022001400041245010100055210006900156260007700225300001400302490000700316520163400323653002101957653001301978653001301991653001302004100002502017700002402042700002602066700002102092700002502113856013202138 2007 eng d a0947-653900aExhaustive analysis of frontal copolymerization of functionalized monovinyl and divinyl monomers0 aExhaustive analysis of frontal copolymerization of functionalize aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcAPR a5862-58720 v133 a

A series of copolymers of 2-hydroxyethyl methacrylate (HEMA)/ glycidyl methacrylate (GMA) and ethylene dimethacrylate (EGDM) were synthesized by frontal polymerization (FP). This study was conducted to investigate the effect of crosslink density, type and concentration of initiator, the use of a complex initiator system, porogen, and diluent on the most relevant parameters of FP, such as sustainability of the front, temperature profile, front velocity, and yield. The products were also characterized for intruded pore volume, pore-size distribution, epoxy-functionality number, and surface morphology. Higher crosslink densities (CLDs) and initiator concentration produced higher front velocities, whereas no trend in front temperature was noted. A complex initiation system was effective in stabilizing and increasing the polymerization yield. Relative to suspension polymerization (SP), FP products synthesized without a solvent were microporous, whereas micro-to-macroporous products were obtained in the presence of a solvent (for HEMA-EGDM polymers). We also present, explain, and discuss the exotic patterns observed under a microscope. We observed two basic types of spatial patterns, namely, planar and nonplanar patterns. The type of planar pattern observed under scanning electron microscopy (SEM) has a spatial impulse that appears as a loop followed by regular periodic motion in the radial and axial directions. This behavior gives rise to a repeating pattern that is a few microns thick. Also, nonplanar patterns, namely, layered concentric rings and winding staircase patterns, were observed under SEM.

10acopolymerization10apatterns10aPolymers10aporosity1 aPujari, Narahari, S.1 aInamdar, Satish, R.1 aAmbekar, Jalindar, D.1 aKulkarni, B., D.1 aPonrathnam, Surendra uhttps://library.ncl.res.in/content/exhaustive-analysis-frontal-copolymerization-functionalized-monovinyl-and-divinyl-monomers-001733nas a2200181 4500008004100000022001400041245004300055210004200098260007700140300001200217490000700229520113700236100002501373700002401398700002501422700002601447856007801473 2007 eng d a1022-133600aWater-triggered frontal polymerization0 aWatertriggered frontal polymerization aPO BOX 10 11 61, D-69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJAN a109-1150 v283 a

A totally new mode of frontal polymerization (FP) of acrylamide is established which is triggered by the simple addition of a minute, specific volume of water. Experimental conditions under which this mode of polymerization yields linear and water-soluble polyacrylamide were carefully established, paving the way to synthesize commercially pertinent homo- and copolymers. A new redox couple was identified to circumvent the imidization and the ensuing gelation, hitherto associated with FP of acrylamide. Effects of reaction variables such as type and concentration of redox couple and volume of water on measurable parameters of FP such as front velocity, front temperature, shape of front and yield have been studied. Two types of redox couples are reported. Nonplanar frontal regime was observed in few redox couples. We could visually observe helical patterns with naked eyes, while layered patterns were observable under SEM. Additionally, micro-phase separation and heterogeneity in the polymer matrix was observed due to unreacted pockets of monomer which evolve via bulk mode. This nonlinear phenomenon is described.

1 aPujari, Narahari, S.1 aInamdar, Satish, R.1 aPonrathnam, Surendra1 aKulkarni, Bhaskar, D. uhttps://library.ncl.res.in/content/water-triggered-frontal-polymerization02287nas a2200289 4500008004100000022001400041245007600055210006900131260007300200300000900273490000700282520131500289653002201604653002101626653001301647653003001660653001801690653002201708653001401730100002201744700002501766700002901791700002501820700002101845700001801866856011301884 2009 eng d a1383-586600aVinyl-2-pyrrolidone derivatized guar gum based aqueous two-phase system0 aVinyl2pyrrolidone derivatized guar gum based aqueous twophase sy aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcFEB a9-130 v653 a

Aqueous two-phase systems (ATPs) are formed when certain combinations of two polymers or polymer and salt are added to water. Phase separation occurs at certain specific concentrations that have similar densities and low interfacial tensions. The present study involves synthesis and application of a novel derivatized guar in aqueous two-phase system. The derivation of guar gum was performed by grafting of 1-vinyl-2-pyrrolidone by a redox reaction in aqueous medium ceric ammonium nitrate (CAN) and potassium Peroxydisulfate(K2S2O8). The ratio of grafting efficiency (%GE) and ratio of grafting (%G) was 56% and 70.1% respectively. The grafted copolymers were characterized for percent yield and FTIR absorbance. A new aqueous two-phase extraction protocol was established using a mixture of derivatized guar and dextran. A phase diagram was constructed based on the phase separation exhibited by the system at 25 degrees C. The partition coefficient was determined for standard bovine serum albumin (BSA), lactate oxidase (LO) and phytase. The partitioning coefficients were 0.479, 1.981, and 2.586 respectively in the Dextran (2 mill ion)/V-GG/H2O system. The influence of an ionic salt sodium chloride (NaCl) was investigated on the partitioning of BSA. (C) 2008 Elsevier B.V. All rights reserved.

10aAqueous two phase10agraft copolymers10aGuar gum10aPartition coefficient (K)10aPhase diagram10aVinyl pyrrolidone10aviscosity1 aKautharapu, Kumar1 aPujari, Narahari, S.1 aGolegaonkar, Sandeep, B.1 aPonrathnam, Surendra1 aNene, Sanjay, N.1 aBhatnagar, D. uhttps://library.ncl.res.in/content/vinyl-2-pyrrolidone-derivatized-guar-gum-based-aqueous-two-phase-system-0