03201nas a2200289 4500008004100000022001400041245009400055210006900149260006700218300001400285490000700299520215700306653000602463653001602469653005502485653002202540653002702562653004802589653001802637653003602655653002402691653003102715653001202746100001502758700001602773856012202789 2005 eng d a0887-624X00aNovel tridentate nitrogen donor as ligand in copper catalyzed ATRP of methyl methacrylate0 aNovel tridentate nitrogen donor as ligand in copper catalyzed AT a111 RIVER ST, HOBOKEN 07030-5774, NJ USAbWILEY-BLACKWELLcNOV a4996-50080 v433 a

A tridentate ligand, BPIEP: 2,6-bis[1-(2,6-diisopropyl phenylimino) ethyl] pyridine, having central pyridine unit and two peripheral imine coordination sites was effectively employed in controlled/''living'' radical polymerization of MXU at 90 degrees C in toluene as solvent, (CuBr)-Br-I as catalyst, and ethyl-2-bromoisobutyrate (EBiB) as initiator resulting in well-defined polymers with polydispersities M-W/M-n <= 1.23. The rate of polymerization follows first-order kinetics, k(app) = 3.4 x 10(-5) s(-1), indicating the presence of low radical concentration ([P*] <= 10(-8)) throughout the reaction. The polymerization rate attains a maximum at a ligand-to-metal ratio of 2:1 in toluene at 90 degrees C. The solvent concentration (v/v, with respect to monomer) has a significant effect on the polymerization kinetics. The polymerization is faster in polar solvents like, diphenylether, and anisole, as compared to toluene. Increasing the monomer concentration in toluene resulted in a better control of polymerization. The molecular weights (M-n,M-SEC) increased linearly with conversion and were found to be higher than predicted molecular (M-n,M-Cal). However, the polydispersity remained narrow, i.e., <= 1.23. The initiator efficiency at lower monomer concentration approaches a value of 0.7 in 110 min as compared to 0.5 in 330 min at higher monomer concentration. The aging of the copper salt complexed. with BPIEP had a beneficial effect and resulted in polymers with narrow polydispersitities and higher conversion. PMMA obtained at room temperature in toluene (33%, v/v) gave PDI of 1.22 (Mn = 8500) in 48 h whereas, at 50 degrees C the PDI is 1.18 (Ma = 10,300), which is achieved in 23 h. The plot of In kapp versus 1/T gave an apparent activation energy of polymerization as (Delta E-app(not equal)) 58.29 KJ/mol and enthalpy of equilibrium (Delta H-eq(0)) to 28.8 KJ/mol. Reverse ATRP of MMA was successfully performed using AIBN in bulk as well as solution. The controlled nature of the polymerization reaction was established through kinetic studies and chain extension experiments. (c) 2005 Wiley Periodicals, Inc.

10a210a6-bis [1-(210a6-diisopropyl phenylimino) ethyl] pyridine (BPIEP)10aActivation energy10aapparent rate constant10aAtom transfer radical polymerization (ATRP)10adiphenylether10aethyl-2-bromoisobutyrate (EBiB)10amethyl methacrylate10apolydispersity index (PDI)10aToluene1 aMittal, A.1 aSivaram, S. uhttps://library.ncl.res.in/content/novel-tridentate-nitrogen-donor-ligand-copper-catalyzed-atrp-methyl-methacrylate-102716nas a2200253 4500008004100000022001400041245012000055210006900175260006800244300001400312490000700326520180900333653001302142653002802155653002502183653001002208653001902218653001802237653001902255100001702274700002802291700001602319856012702335 2005 eng d a0887-624X00aStructure of poly(L-lactic acid)s prepared by the dehydropolycondensation of L-lactic acid with organotin catalysts0 aStructure of polyLlactic acids prepared by the dehydropolyconden a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcMAY a2164-21770 v433 a

The synthesis of low-molecular-weight (weight-average molecular weight < 45,000 g/mol) lactic acid polymers through the dehydropolycondensation of L-lactic acid was investigated. Polymerizations were carried out in solution with solvents (xylene, mesitylene, and decalin), without a solvent using different Lewis acid catalysts (tetraphenyl tin and tetra-n-butyldichlorodistannoxane), and at three different polymerization temperatures (143, 165, and 190 degrees C). The products were characterized with differential scanning calorimetry, size exclusion chromatography, vapor pressure osmometry, C-13 NMR, and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF). The resulting polymers contained less than 1 mol % lactide, as shown by NMR. The number-average molecular weights were calculated from the ratio of the area peaks of ester carbonyl and carboxylic acid end groups via C-13 NMR. The stereosequences were analyzed by C-13 NMR spectroscopy on the basis of triad effects. Tetraphenyl tin was an effective transesterification catalyst, and the randomization of the stereosequence at 190 degrees C was observed. In contrast, the distannoxane catalyst caused comparatively less transesterification reaction, and the randomization of the stereosequences was slow even at 190 degrees C. The L-lactic acid and D-lactic acid isomers were added to the polymer chain in a small, blocky fashion. The MALDI-TOF spectra of poly(L-lactic acid) (PLA) chains doped with Na+ and K+ cations showed that the PLA chains had the expected end groups. The MALDI-TOF analysis also enabled the simultaneous detection of the cyclic oligomers of PLA present in these samples, and this led to the full structural characterization of the molecular species in PIA. (c) 2005 Wiley Periodicals, Inc.

10aC-13 NMR10adehydropolycondensation10aLewis acid catalysts10aMALDI10apolymerization10arandomization10astereosequence1 aShyamroy, S.1 aGarnaik, Baijayantimala1 aSivaram, S. uhttps://library.ncl.res.in/content/structure-polyl-lactic-acids-prepared-dehydropolycondensation-l-lactic-acid-organotin-000657nas a2200157 4500008004100000022001400041245010400055210006900159260007200228300001400300490000700314100001500321700001600336700001700352856013000369 2006 eng d a0024-929700aUnfavorable coordination of copper with methyl vinyl ketone in atom transfer radical polymerization0 aUnfavorable coordination of copper with methyl vinyl ketone in a a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAUG  a5555-55580 v391 aMittal, A.1 aSivaram, S.1 aBaskaran, D. uhttps://library.ncl.res.in/content/unfavorable-coordination-copper-methyl-vinyl-ketone-atom-transfer-radical-polymerization-002362nas a2200169 4500008004100000022001400041245017000055210006900225260007100294300001400365490000700379520162400386100002002010700001502030700001602045856013102061 2007 eng d a0024-929700aCopolyesters based on poly(butylene terephthalate)s containing cyclohexyl and cyclopentyl ring: Effect of molecular structure on thermal and crystallization behavior0 aCopolyesters based on polybutylene terephthalates containing cyc a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcSEP a6906-69150 v403 a

In an effort to understand the role of molecular structure on the thermal properties of polyesters and copolyesters, the following polyesters were synthesized: poly(1,4-cyclohexane dimethylene terephthalate) (PCT), poly(butylene-1,4-cyclohexane dicarboxylate) (PBCD), poly (1,3-cyclopentane dimethylene terephthalate) (PCPDT), and poly(butylene-1,3-cyclopentane dicarboxylate) (PBCP). PCT and PCPDT are semicrystalline polymers with crystallization and melting temperatures higher than poly(butylene terephthalate) (PBT). However, PBCD and PBCP have lower glass transition temperature than PBT. From these homopolymers a series of poly(butylene-co-1,4-cyclohexane dimethylene terephthalate) (P(BT-co-CT )), poly(butylene terephthalate-co-1,4cyclohexane dicarboxylate) (P(BT-co-BCD)), poly(butylene-co-1,3-cyclopentylene dimethylene) (P(BT-co-CPDT)), and poly(butylene terephthalate-co-1,3-cyclopentane dicarboyxlate) (P(BT-co-PBCP)) random copolyesters were synthesized for the first time, and their cocrystallization behavior was investigated using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The copolymers were found to be statistically random and crystallized in all compositions. The P(BT-co-CT) and (P(BT-co-CPDT) copolyesters exhibited typical eutectic behavior in melting and crystallization, which indicated isodimorphic cocrystallization behavior. On the other hand, in the case of P(BT-co-BCD) and P(BT-co-PBCP) copolymers, the melting and crystallization temperatures showed linear dependency with composition, indicating isomorphic-like crystallization behavior.

1 aSandhya, T., E.1 aRamesh, C.1 aSivaram, S. uhttps://library.ncl.res.in/content/copolyesters-based-polybutylene-terephthalates-containing-cyclohexyl-and-cyclopentyl-ring-002324nas a2200265 4500008004100000022001400041245013400055210006900189260007300258300001200331490000800343520134700351653001901698653002301717653001401740653002401754653002101778653002201799653002601821100002201847700002501869700002201894700001601916856012601932 2007 eng d a0378-775300aHigh-temperature, polymer-graphite hybrid composites for bipolar plates: effect of processing conditions on electrical properties0 aHightemperature polymergraphite hybrid composites for bipolar pl aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJAN a702-7070 v1633 a

High-temperature thermoplastic-graphite composites are prepared using polyphenylene sulfide (PPS) and polyether sulfone (PES) containing natural graphite powder. All samples are prepared by high pressure compaction and heating to high temperatures. The effect of a third additional conducting component on the electrical resistance of these composites is studied. A low resistance of the order of 0.1 Omega can be obtained even for a graphite concentration of 50% by addition of the third component. The effect of a mixing/blending technique on the anisotropy of conductivity is investigated. Solution blending of PES with graphite leads to lower anisotropy values than powder mixing and compression moulding. The samples when exposed continuously to a working temperature of 100 degrees C give a small but significant reduction in electrical resistance. X-ray diffraction studies on composites prepared by different techniques indicate that there is restructuring and crystallite re-orientation of the graphite phase in the samples. A large reduction in the crystallite size is observed for samples prepared by solution blending while re-orientation occurs after heat treatment. The changes in electrical properties can be correlated with these structural transformations in the composites. (c) 2006 Elsevier B.V. All rights reserved.

10abipolar plates10aconducting polymer10afuel cell10agraphite composites10ahybrid materials10apolyether sulfone10apolypherylene sulfide1 aRadhakrishnan, S.1 aRamanujam, B., T. S.1 aAdhikari, Arindam1 aSivaram, S. uhttps://library.ncl.res.in/content/high-temperature-polymer-graphite-hybrid-composites-bipolar-plates-effect-processing-001579nas a2200217 4500008004100000022001400041245014700055210006900202260005700271300001200328490000700340520073800347653003101085653001601116653002901132653002801161653002301189100001501212700001601227856011801243 2011 eng d a0170-083900aPolymerization of ethylene to branched poly(ethylene)s using ansa-eta(5)-monofluorenyl cyclohexanolato zirconium(IV) complex/methylaluminoxane0 aPolymerization of ethylene to branched polyethylenes using ansae a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcJUL a383-3990 v673 a

ansa-eta(5)-Monofluorenyl cyclohexanolato zirconium complex 3 was shown to be active for the polymerization of ethylene when activated with methylaluminoxane (MAO) at 5 bar. Up to a polymerization temperature of 40 A degrees C, 3/MAO resulted in linear poly(ethylene)s with saturated chain ends. However, at polymerization temperatures of 60, 80, and 100 A degrees C, a mixture of branched poly(ethylene)s, linear alpha-olefins and long chain alkanes was obtained. The poly(ethylene)s produced at 80 and 100 A degrees C exhibited a bimodal molecular weight distribution indicative of multiple active species. Very high molecular weight (M (v) > 5 x 10(5)) linear poly(ethylene)s were obtained using 3/MAO at 25 A degrees C.

10aansa-Monofluorenyl complex10aBimodal MWD10aBranched poly(ethylene)s10aEthylene polymerization10aMethyl aluminoxane1 aRajesh, A.1 aSivaram, S. uhttps://library.ncl.res.in/content/polymerization-ethylene-branched-polyethylenes-using-ansa-eta5-monofluorenyl-001813nas a2200157 4500008004100000022001400041245009600055210006900151260007600220300001400296490000700310520118000317100001501497700001601512856012701528 2011 eng d a0032-388800aPolymerization of ethylene using amido functional half-sandwich complexes of group 4 metals0 aPolymerization of ethylene using amido functional halfsandwich c aCOMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USAbWILEY-BLACKWELLcOCT a2103-21080 v513 a

Ligands (C(13)H(9))(2,6-R(2)C(6)H(3)NH)SiPh(2) [R = (i)Pr (2a), Me (2b)] were synthesized by single deprotonation of the amino group in 2,6-dialkylanilines with n-BuLi at -78 degrees C followed by reaction with fluorenyl diphenyl silyl chloride [FluSi(Ph(2))Cl]. Single crystal X-ray diffraction studies revealed different geometries around the nitrogen atom for the two compounds. Titanium and zirconium complexes (3a-3d) were prepared by double deprotonation of the ligands with n-butyl lithium (n-BuLi) followed by reaction with the respective metal chlorides, MCl(4) (THF)(2). Polymerization of ethylene was performed using these complexes as catalyst precursors along with methylaluminoxane (MAO) as an activator at 5 bar pressure. Complexes 3a-3d/MAO exhibited moderate catalyst activities for polymerization of ethylene and resulted in high molecular weight linear poly(ethylene)s (M(v) > 4 3 10(5) g/mol). Catalyst activities were much lower when compared to similar N-alkyl substituted complexes presumably due to the resonance effect of the aromatic group on the amido nitrogen. POLYM. ENG. SCI., 51:2103-2108, 2011. (C) 2011 Society of Plastics Engineers

1 aRajesh, A.1 aSivaram, S. uhttps://library.ncl.res.in/content/polymerization-ethylene-using-amido-functional-half-sandwich-complexes-group-4-metals-002014nas a2200181 4500008004100000022001400041245011800055210006900173260007100242300001400313490000700327520130200334100001801636700001801654700001601672700001701688856012701705 2012 eng d a0024-929700aReactive polymers bearing styrene pendants through selective anionic polymerization of 4-vinylbenzyl methacrylate0 aReactive polymers bearing styrene pendants through selective ani a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAPR a3387-33930 v453 a

Selective anionic polymerization of 4-vinylbenzyl methacrylate at methacrylate site has been achieved using resonance stabilized anionic initiators such as 1,1-diphenylhexyllithium (DPHLi) and tritylpotassium (TritylK) in tetrahydrofuran (THF) at -78 degrees C. Polymerization proceeded selectively through methacrylate functionality of the monomer in a controlled manner and produced polymers and copolymers with narrow molecular weight distribution at low temperatures (<=-40 degrees C). H-1 NMR of the polymer showed the presence of styrene pendants in every monomeric repeating unit. The polymerization results confirm that the resonance stabilized carbanions with an optimum pK(a) (30 <= pK(a) <= 32) of their conjugate acids such as DPHLi and TritylK do not react with styrene functionality at 78 degrees C. The selective initiation without cross-linking is attributed to the differences in the electronegativity between polar methacrylate and styrene functionalities and an attenuation of initiator reactivity at low temperature. Poly(4-vinylbenzyl methacrylate) and its copolymers with the vinyl pendant in close proximity with ester linkage are very reactive and unstable, readily undergoing cross-linking in solution or in solid state with or without a radical initiator.

1 aMohan, Murali1 aRaghunadh, V.1 aSivaram, S.1 aBaskaran, D. uhttps://library.ncl.res.in/content/reactive-polymers-bearing-styrene-pendants-through-selective-anionic-polymerization-4-000621nas a2200133 4500008004100000022001400041245009600055210006900151260010200220300001200322490000800334100001600342856012900358 2013 eng d a0011-389100aSustainable materials based on aliphatic polyesters: teaching old chemistry some new tricks0 aSustainable materials based on aliphatic polyesters teaching old aC V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIAbINDIAN ACAD SCIENCEScOCT a879-8800 v1051 aSivaram, S. uhttps://library.ncl.res.in/content/sustainable-materials-based-aliphatic-polyesters-teaching-old-chemistry-some-new-tricks-001331nas a2200169 4500008004100000022001400041245016100055210006900216260005700285300001200342490000700354520061000361100001700971700002800988700001601016856012901032 2015 eng d a0170-083900aHigh molecular weight polylactic acids by polyesterification using diisopropylcarbodiimide (DIPC) and 4-(dimethylamino) pyridinium ptoluene sulfonate (DPTS)0 aHigh molecular weight polylactic acids by polyesterification usi a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcMAR a405-4150 v723 a

High molecular weight poly(l-lactic acid) has been prepared from the corresponding functionally terminated oligomers employing a polyesterification method at room temperature using diisopropylcarbodiimide and 4-(dimethylamino) pyridinium-p-toluene sulfonate. Self-condensation of hydroxyl and carboxylic acid-terminated poly(l-lactic acid) oligomers (M (n) : similar to 1,000) resulted in polymers with high molecular weights (M (n) > 45,000) under mild conditions. End-group analysis by MALDI-TOF provided evidence for N-acylurea formation in the product under the reaction conditions employed.

1 aShyamroy, S.1 aGarnaik, Baijayantimala1 aSivaram, S. uhttps://library.ncl.res.in/content/high-molecular-weight-polylactic-acids-polyesterification-using-diisopropylcarbodiimide-000600nas a2200145 4500008004100000020002000041022002000061245011100081210006900192260002500261300000900286100002200295700001600317856012100333 2017 eng d a978-177188297-2 a978-177188296-500aSynthesis of functional polymers of polar and nonpolar monomers by living and/or controlled polymerization0 aSynthesis of functional polymers of polar and nonpolar monomers  bApple Academic Press a3-561 aChowdhury, S., R.1 aSivaram, S. uhttps://library.ncl.res.in/content/synthesis-functional-polymers-polar-and-nonpolar-monomers-living-andor-controlled00425nas a2200145 4500008004100000022001400041245004400055210004100099260000800140300001400148490000800162100001600170700001600186856007700202 2019 eng d a0011-389100aBhaskar Dattatraya Kulkarni (1949-2019)0 aBhaskar Dattatraya Kulkarni 19492019 cAPR a1261-12620 v1161 aKumar, Ravi1 aSivaram, S. uhttps://library.ncl.res.in/content/bhaskar-dattatraya-kulkarni-1949-2019