K. Dayananda

Bio: K. Dayananda is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Solution polymerization & Methyl methacrylate. The author has an hindex of 2, co-authored 2 publications receiving 39 citations.

ATRP of methyl methacrylate using a novel binol ester-based bifunctional initiator

Abstract: Novel bifunctional initiators [1,1'-Bi-2-naphthol bis(2-bromo-2-methylpropionate); (R)-, (S)-, and racemic-] were synthesized from the esterification of 1,1'-bi-2-naphthol and used as initiators in atom transfer radical polymerization (ATRP) in conjunction with N,N,N',N',N-pentamethyldiethylenetriamine (PMDETA), and copper (I) bromide or copper (I) chloride. The initiators synthesized were completely characterized by UV, FTIR, NMR, and Mass spectroscopies. A detailed investigation of the ATRP of methyl methacrylate (MMA) with the bifunctional initiators (BBiBN) along with CuBr or CuCl/MDETA catalyst system in anisole was carried out at 30 °C. Thus, MMA polymerization is shown to proceed with first-order kinetics, with predicted molecular weight, and narrow polydispersity indices. The ATRP of glycidyl methacrylate (GMA) and tert-butyl acrylate (tBA) were also performed with BBiBN initiator in conjunction with CuBr/PMDETA catalyst system. The polymerization of GMA was carried out at 30 °C, but tBA was polymerized at 60 °C. Gel permeation chromatography (GPC), FTIR, NMR, UV spectroscopies, and TGA were used for the characterization of the polymers synthesized.

Synthesis and Characterization of Block Copolymers of P(MMA‐b‐n‐BA‐b‐MMA) via Ambient Temperature ATRP of MMA

Abstract: A binol ester initiator was used as a bifunctional ATRP initiator in combination with PMDETA/copper bromide catalyst system in DMF to synthesize n‐butyl acrylate macroinitiator at 50°C. The resulting macroinitiator was used for a detailed investigation of the ATRP of methyl methacrylate (MMA) with CuCl/N,N,N′,N′,N″‐pentamethyldiethy‐lenetriamine (PMDETA) catalyst system in anisole at 30°C. Thus, the MMA polymerization is shown to proceed with first order kinetics, with predicted molecular weight and narrow polydispersity indices. Gel permeation chromatography (GPC) and NMR were used for the characterization of the polymers synthesized.

Catalyst components for the polymerization of olefins

Abstract: Catalyst components for the(co)polymerization of ethylene comprising Ti, Mg, halogen, ORI groups, where RI is a C1-C12 hydrocarbon group optionally containing heteroatoms, having ORI/Ti molar ratio in the range 0.1-1.5, a Mg/Ti molar ratio of less than 8, an amount of titanium, with respect to the total weight of said solid catalyst component, higher than 4% by weight characterized by a specific SS-NMR pattern are particularly useful for preparing narrow MWD crystalline ethylene polymers.

Atom Transfer Radical Polymerization of Glycidyl Methacrylate: A Functional Monomer

Abstract: Summary: A detailed investigation of the polymerization of glycidyl methacrylate (GMA), an epoxy-functional monomer, by atom transfer radical polymerization (ATRP) was performed. Homopolymers were prepared at relatively low temperatures using ethyl 2-bromoisobutyrate (EBrIB) as the initiator and copper halide (CuX) with N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) as the catalyst system. The high polymerization rate in the bulk did not permit polymerization control. However, homopolymerization in solution enabled us to explore the effects of different experimental parameters, such as temperature, solvent (toluene vs. diphenyl ether) and initiator concentration, on the controllability of the ATRP process. SEC analysis of the homopolymers synthesized confirmed the importance of solvent character on molecular weight control, the lowest polydispersity indices () and the highest efficiencies being found when the polymerizations were performed in diphenyl ether in combination with a mixed halide technique. A novel poly(glycidyl methacrylate)-block-poly(butyl acrylate) (PGMA-b-PBA) diblock copolymer was prepared through ATRP using PGMA-Cl as a macro-initiator. This chain growth experiment demonstrated a good living character under the conditions employed, while simultaneously indicating a facile synthetic route for this type of functional block copolymer. In addition, the isotacticity parameter for the PGMAs obtained was estimated using 1H NMR analysis which gave a value of σGMA = 0.26 in agreement with that estimated in conventional radical polymerization. SEC chromatograms of PGMA-Cl macroinitiator and PGMA-b-PBA diblock copolymer.

Mechanical reconfiguration of stereoisomers.

Abstract: Poly(methyl acrylate) of varying molecular weight was grown from the enantiopure ditopic initiator (R)- or (S)-1,1′-binaphthyl-2,2′-bis-(2-bromoisobutyrate). Subjecting CH3CN solutions of high-molecular-weight derivatives (MN > 25 kDa) to sonication at 0 °C resulted in >95% racemization after 24 h, as determined by circular dichroism; no appreciable racemization was observed in low-molecular-weight derivatives. Control experiments excluded the possibility of a thermal racemization mechanism.

Atom transfer radical polymerization of 6-O-methacryloyl-1,2;3,4-di-O-isopropylidene-D-galactopyranose in solution

Abstract: A detailed exploration of the atom transfer radical polymerization (ATRP) of a sugar-carrying monomer, 6-O-methacryloyl-1,2;3,4-di-O-isopropylidene-D-galactopyranose (MAIPGal) was performed. The factors pertinent to ATRP, such as initiators, ligands, catalysts, and temperature were optimized to obtain good control over the polymerization. The kinetics were examined in detail when the polymerization was initiated by methyl 2-bromoisopropionate (2-MBP), ethyl 2-bromoisobutyrate (2-EBiB), or a macroinitiator, [α-(2-bromoisobutyrylate)-ω-methyl PEO] (PEO–Br), with bipyridine (bipy) as the ligand at 60 °C or by 2-EiBB with N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) as the ligand at room temperature (23 °C). The effects of the catalysts (CuBr and CuCl) were also investigated. We demonstrate that the successful ATRP of MAIPGal can be achieved for 2-EBiB/CuBr/bipy and 2-MBP/CuCl/bipy at 60 °C and for 2-EBiB/CuBr/PMDETA at room temperature. The initiation by 2-EBiB at room temperature with PMDETA as the ligand should be the most optimum operation for its moderate condition and suppression of many side reactions. Chain extension of P(MAIPGal) prepared by ATRP with methyl methacrylate (MMA) as the second monomer was carried out and a diblock copolymer, P(MAIPGal)-b-PMMA, was obtained. Functional polymers, poly(D-galactose 6-methacrylate) (PGMA), PEO-b-PGMA, and PGMA-b-PMMA were obtained after removal of the protecting groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 752–762, 2005