@article { ISI:000266093800005, title = {MgCl2 center dot 4(CH3)(2)CHOH: a new molecular adduct and super active polymerization catalyst support}, journal = {Journal of Physical Chemistry C}, volume = {113}, number = {20}, year = {2009}, month = {MAY}, pages = {8556-8559}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A new molecular adduct, MgCl(2 center dot)4(CH3)(2)CHOH, has been synthesized and characterized for structural aspects and demonstrated for super active ethylene polymerization activity with TiCl4 to ultrahigh molecular weight polyethylene in high yield.

}, issn = {1932-7447}, doi = {10.1021/jp9026546}, author = {Thushara, K. S. and Mathew, Renny and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Bhaduri, Sumit and Gopinath, Chinnakonda S.} } @article { ISI:000295843900024, title = {MgCl2 center dot 6PhCH(2)OH - a new molecular adduct as support material for ziegler-natta catalyst: synthesis, characterization and catalytic activity}, journal = {Dalton Transactions}, volume = {40}, number = {41}, year = {2011}, month = {SEP}, pages = {10936-10944}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Benzyl alcohol has been used to prepare a single phase MgCl2 center dot 6BzOH molecular adduct as a support for an ethylene polymerization catalyst (Ziegler catalyst). The structural, spectroscopic and morphological aspects of the MgCl2 center dot 6BzOH molecular adduct and the Ziegler catalyst have been thoroughly studied by various physicochemical characterization techniques. The presence of MgO6 octahedrons due to the interaction of Mg2+ with six -OH groups of the benzyl alcohol is confirmed from a Raman feature at 703 cm(-1), and structural studies. The supported catalyst activity has been evaluated for the ethylene polymerization reaction. The lower polymerization activity of the titanated Ziegler-Natta catalyst compared with a standard catalyst is attributed to the strong interaction of titanium chloride with the support and associated electronic factors.

}, issn = {1477-9226}, doi = {10.1039/c1dt10786k}, author = {Gnanakumar, Edwin S. and Thushara, K. S. and Bhange, Deu S. and Mathew, Renny and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Bhaduri, Sumit and Gopinath, Chinnakonda S.} } @article { ISI:000308361400011, title = {MgCl2 center dot 4((CH3)(2)CHCH2OH): a new molecular adduct for the preparation of TiClx/MgCl2 catalyst for olefin polymerization}, journal = {Dalton Transactions}, volume = {41}, number = {37}, year = {2012}, month = {JUL}, pages = {11311-11318}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A new molecular adduct of MgCl2 with isobutanol, namely MgCl2 center dot 4((CH3)(2)CHCH2OH) (MgiBOH), has been prepared as a precursor to the supporting material for an olefin polymerization catalyst. The MgiBOH adduct and final titanated Ziegler-Natta catalysts have been thoroughly characterized by powder XRD, thermal analysis, Raman spectroscopy and solid-state NMR for structural and spectroscopy aspects. A peak observed at 712 cm(-1) in the Raman spectra of MgiBOH indicates the characteristic Mg-O-6 breathing mode and the formation of the adduct. The diffraction feature at 2 theta = 7.8 degrees (d = 11.223 angstrom) in the XRD confirms the adduct formation and the layered structure. The aim of the present article is to study how the insertion of a bulky isobutanol moiety affects the structural and electronic properties of the MgCl2 isobutanol molecular adduct. Indeed, the focus of the present study is to explore how the presence of isobutanol, in the initial molecular adduct, influences the final Z-N catalyst properties and its activity.

}, issn = {1477-9226}, doi = {10.1039/c2dt31211e}, author = {Thushara, K. S. and Gnanakumar, Edwin S. and Mathew, Renny and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Bhaduri, Sumit and Gopinath, Chinnakonda S.} } @article { ISI:000311190800033, title = {MgCl2 center dot 6C(6)H(11)OH: a high mileage porous support for ziegler-natta catalyst}, journal = {Journal of Physical Chemistry C}, volume = {116}, number = {45}, year = {2012}, month = {NOV}, pages = {24115-24122}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A new and single phase molecular adduct of MgCl2 with six cyclohexanol molecules MgCl2 center dot 6C(6)H(11)OH (MgCyOH) has been synthesized. Structural insight to this adduct was obtained by a variety of physicochemical methods. C-13 CPMAS spectrum and single pulse MAS spectra with high power proton decoupling recorded at different relaxation time showed the presence of two different sets of magnetically unequal cylcohexanol molecules present around Mg2+. A Raman feature of MgCyOH at 712 cm(-1) confirms that cylcohexanol molecules are present around Mg2+ in an octahedral environment. MgCyOH has been used as support material to prepare Ziegler-Natta (Z-N) active catalyst. Textural property of above Z-N catalyst exhibits high surface area (236 m(2)/g) with high porosity. Above active catalyst has been screened for ethylene polymerization. Depending on the cocatalyst employed (Me3Al, Et3Al, and iso-Bu3Al) and ethylene pressure, polyethylene yield varies an order of magnitude, from 378 to 3570 g/g catalyst, indicating a possible creation of different active sites and different interaction between cocatalyst and catalyst.

}, issn = {1932-7447}, doi = {10.1021/jp3074078}, author = {Gnanakumar, Edwin S. and Thushara, K. S. and Gowda, Ravikumar R. and Raman, Sumesh K. and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Chakraborty, Debashis and Gopinath, Chinnakonda S.} } @article { ISI:000315707700003, title = {MgCl2 center dot 6CH(3)OH: a simple molecular adduct and its influence as a porous support for olefin polymerization}, journal = {ACS Catalysis}, volume = {3}, number = {3}, year = {2013}, month = {MAR}, pages = {303-311}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A single phase molecular adduct, MgCl2 center dot 6CH(3)OH has been synthesized using MgCl2 and the simplest alcohol, methanol. Structural, spectroscopic, and morphological studies have been carried out for a better understanding of the single phase MgCl2 center dot 6CH(3)OH adduct. C-13 CPMAS solid state NMR studies show all six methanol molecules are magnetically equivalent and present in a single environment around the Mg2+ center. Raman spectral analysis of the characteristic peak at 708 cm(-1) substantiates octahedral coordination of six CH3OH molecules around Mg2+. Solid state C-13 NMR measurements, made after heat treatment at different temperatures, have been utilized to understand the variations in CH3OH stoichiometry and coordination around Mg2+ with temperature. A titanated active catalyst, TiCl4 on MgCl2 center dot 6CH(3)OH, has also been synthesized and subjected to detailed characterizations. The active catalyst shows high surface area (102 m(2)/g) and mesoporosity. The titanated catalyst has been screened for ethylene polymerization reactions using different cocatalysts (R3Al; R= -CH3, -CH2CH3, and -CH2CH(CH3)(2)). A total of 7.25 kg of polyethylene per gram of catalyst has been obtained with Me3Al cocatalyst, which is six times higher in activity compared with commercial Me3Al/TiCl4/MgCl2 center dot 6EtOH-supported orted catalystAlthough porosity influences the catalytic activity, other factors also seem to contribute to the total catalytic activity.

}, keywords = {heterogeneous catalysis, MgCl2, Molecular adduct, olefin polymerization, Ziegler-Natta catalyst}, issn = {2155-5435}, doi = {10.1021/cs300730j}, author = {Gnanakumar, Edwin S. and Gowda, Ravikumar R. and Kunjir, Shrikant and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Chakraborty, Debashis and Gopinath, Chinnakonda S.} } @article {42995, title = {Molecular motifs for additives that retard PEO crystallization}, journal = {Polymer Engineering \& Science}, volume = {57}, year = {2017}, month = {AUG}, pages = {857-864}, type = {Article}, abstract = {

We investigate the influence of several bifunctional phenol additives (resorcinol: RES, hydroquinone: HYD, p-hydroxybenzoic acid: PHBA, and p-nitrophenol: PNP) on the crystallization of matrix polymer, polyethyleneoxide. We employ solid state Nuclear Magnetic Resonance spectroscopy (NMR), Differential Scanning Calorimetry (DSC), optical microscopy, and Small Angle X-ray Scattering (SAXS) to investigate crystallization of the additivated PEO and compare with Density Functional Theory (DFT) calculations of additive-PEO interactions. Additive-polymer interactions are a function of the functional groups on the additive. Temperature-dependent spherulitic growth rate measurements from optical microscopy and SAXS lamellar long spacings indicate a distinct trend in the effect of additives on PEO crystallization. Change in PEO crystallization is most pronounced with PNP, followed by PHBA and finally RES and HYD. This trend correlates qualitatively with the binding energies of additive-PEO interactions from DFT studies. Our results suggest that DFT calculations might be a useful screening tool to evaluate the influence of additives on polymer crystallization. POLYM. ENG. SCI., 2016. {\textcopyright} 2016 Society of Plastics Engineers

}, doi = {10.1002/pen.24462}, author = {Shrivastava, Sudhakar Dinesh and Eldho, Kavalakal Mathai and Rajamohanan, P. R. and Ajithkumar, Thalasseril G. and Vanka, Kumar and Kumaraswamy, Guruswamy} } @article {44516, title = {Mechanism of the formation of microphase separated water clusters in a water-mediated physical network of perfluoropolyether tetraol}, journal = {Soft Matter}, volume = {14}, year = {2018}, month = {MAR}, pages = {2339-2345}, abstract = {

Perfluoropolyether tetraol (PFPE tetraol) possesses a hydrophobic perfluoropolyether chain in the backbone and two hydroxyl groups at each chain terminal, which facilitates the formation of hydrogen bonds with water molecules resulting in the formation an extended physical network. About 3 wt\% water was required for the formation of the microphase separated physical network of PFPE tetraol. The mechanism responsible for the microphase separation of water clusters in the physical network was studied using a combination of techniques such as NMR spectroscopy, molecular dynamics (MD) simulations and DSC. MD simulation studies provided evidence for the formation of clusters in the PFPE tetraol physical network and the size of these clusters increased gradually with an increase in the extent of hydration. Both MD simulations and NMR spectroscopy studies revealed that these clusters position themselves away from the hydrophobic backbone or vice versa. The presence of intra-and inter-chain aggregation possibility among hydrophilic groups was evident. DSC results demonstrated the presence of tightly and loosely bound water molecules to the terminal hydroxyl groups of PFPE tetraol through hydrogen bonding. The data from all the three techniques established the formation of a physical network driven by hydrogen bonding between the hydrophilic end groups of PFPE tetraol and water molecules. The flexible nature of the PFPE tetraol backbone and its low solubility parameter favour clustering of water molecules at the terminal groups and result in the formation of a gel.

}, issn = {1744-683X}, doi = {10.1039/c7sm02181j}, author = {Deshpande, Ashwini A. and Torris, Arun A. T. and Pahari, Swagata and Menon, Shamal K. and Badiger, Manohar V. and Rajamohanan, P. R. and Wadgaonkar, Prakash P. and Roy, Sudip and Tonelli, Claudio} }