Sreekumar, K; Rani, Joseph; Pramitha, V; Sudha Kartha, C(Indian Academy of Sciences, December , 2010)
[+]
[-]
Abstract:
Plane-wave transmission gratings were stored in the same location of silver-
doped photopolymer ¯lm using peristrophic multiplexing techniques. Constant and vari-
able exposure scheduling methods were adopted for storing gratings in the ¯lm using
He{Ne laser (632.8 nm). The role of recording geometry on the dynamic range of the ma-
terial was studied by comparing the results obtained from both techniques. Peristrophic
multiplexing with rotation of the ¯lm in a plane normal to the bisector of the incident
beams resulted in better homogenization of di®raction e±ciencies and larger M/# value.
A new photopolymerizable recording media is introduced based on poly
(vinyl alcohol) and vinyl acetate sensitized with methylene blue. It is observed
that this MBPVA/VAc system can be reused a number of times without
significant decrease in diffraction . The PVA-VAc ratio was optimized
at 2:1. Diffraction efficiency of 6.3% was obtained without any fixing at a dye
concentration of 9.3 10 4 mol/l at an exposure of 750 mJ/cm2. The material is
attractive on account of its reusability.
A new photopolymerizable recording media is introduced based on poly
(vinyl alcohol) and vinyl acetate sensitized with methylene blue. It is observed
that this MBPVA/VAc system can be reused a number of times without
significant decrease in diffraction efficiency. The PVA-VAc ratio was optimized
at 2:1. Diffraction efcienc4y of 6.3% was obtained without any fixing at a dye
concentration of 9.3 x 10- mol/l at an exposure of 750mJ/cm2. The material is
attractive on account of its reusability.
Sreekumar, K; Rajesh Krishnan, G(Taylor & Francis, February 22, 2010)
[+]
[-]
Abstract:
Poly(amidoamine) dendrimers were synthesized on cross-linked aminomethyl polystyrene. Palladium
complexes of supported dendrimers prepared by ligand exchange method were reduced to dendrimernanoparticle
conjugates supported on polystyrene resin. The supported nanoparticles were used as
heterogeneous catalysts for the Suzuki coupling between aryl boronic acids and aryl halides. Various factors
affecting the catalysts performance were studied. Higher generation dendrimers gave well-defined
nanoparticles without agglomeration and these particles showed good catalytic performance
Sreekumar, K; Sudheesh Kumar, K(Taylor & Francis, June 1, 2007)
[+]
[-]
Abstract:
Various polyurethanes containing photoactive bis(azo) and bis(o-nitrobenzyl)
groups in the main chain were synthesized by polyaddition reactions of diols such
as bis(4-hydroxyphenylazo)-2,20-dinitrodiphenylmethane, 4-hydroxy-3-methylphenylazo-
40-hydroxyphenylazo-2,20-dinitrodiphenylmethane and bis(4-hydroxy-3-
methylphenylazo)-2,20-dinitrodiphenylmethane with hexamethylene di-isocyanate
(HMDI), in dimethyl acetamide (DMAc) in the presence of di-n-butyltin dilaurate
(DBTDL) as catalyst. All of them were characterized by IR, UV-vis, 1H NMR and
13C NMR spectra and also by thermogravimetric analysis (TGA), differential scanning
calorimetry (DSC) and gel permeation chromatography (GPC).
Description:
International Journal of Polymeric Materials, 58:160–166, 2009
This manuscript describes the first example of silver ion complex of a dendritic tetranitrile ligand catalyzed
one-pot three component Mannich reaction and 1,5-benzodiazepine synthesis. The catalyst can be separated from the
products by a change in the solvent. The catalyst is reusable.