V. Mahadevan

Poly(maleimide-amine)s and poly(maleimide-amine)ethers

Abstract Syntheses and properties of poly(maleimide-amine)s and poly(maleimide-amine)ethers from bischloromaleimide are reported. Three model compounds have been prepared and the polymers have been characterized spectrally by comparison with the model compounds. The polymers possess inherent viscosities in the 0.3 to 0.5 dl/g range.

Transition metal ions supported on hydrogels as hydrogenation catalysts

Abstract Synthesis of new hydrogel polymers based on 2-hydroxyethyl methacrylate and other functional monomers is described. These copolymers are useful for anchoring palladium and rhodium species. The resulting supported catalysts are effective for the hydrogenation of alkenes, alkynes and dienes under mild conditions. The supported catalysts have been characterised by chemical analysis, particle size measurements, IR, TGA and X-ray photoelectron spectra. Kinetics of hydrogenation have been evaluated using the concepts applicable to slurry reactors. The hydrogenation proceed through the ‘unsaturate route’. Relative reactivities of a few substrates, solvent and particle size effects and selectivities by product analysis have been assessed. These catalysts possess excellent recycling efficiencies.

Synthetic studies on aliphatic-aromatic co-polyureas

Abstract Aliphatic-aromatic co-polyureas have been prepared using 1,4-bis (isocyanatomethyl)-2,5-dimethylbenzene and 1,5-bis(isocyanatomethyl)-2,4-dimethylbenzene with various diamines. The polymers have been characterized by elemental analysis, TGA, DTA, IR, density and viscosity measurements.

Synthesis of some low glass transition temperature polytetrahydrofuran polymers

Abstract Samples of hydroxy-terminated and amine-terminated (polytetrahydrofuran; PTHF) of various molecular weights were prepared by the polymerization of tetrahydrofuran with boron trifluoride ethereate in three steps. These PTHFs were characterized by molecular weight, hydroxyl number, amine equivalent and i.r. They were then converted to isocyanate-terminate prepolymers and then cured with diols and diamines. The resulting polymers were characterized by i.r., viscosity and density measurements.

Synthesis and properties of polyester based polyurethanes

Abstract Hydroxyl terminated polyesters were prepared by a melt condensation technique using adipic acid and various diols. They were characterised by hydroxyl number, acid number and intrinsic viscosities in benzene. The polyesters were reacted with excess tolylene diisocyanate to yield isocyanate terminated prepolymers and subsequently cured with diols and diamines. These polymers were characterised by i.r. spectra, viscosity measurements and thermogravimetric analysis. The glass transition temperature of the polymers were found to be in the region −25 to −55. The influences of prepolymers and curing reagents are discussed with respect to the low temperature flexibility and thermal stability of the polyurethanes.

Synthesis of phosphorus-containing alternating copolymers

Abstract Phosphorus-containing alternating copolymers were synthesized by the reaction of nucleophilic monomers M N with electrophilic monomers M E . Methyl acrylate and γ-butyrolactone were used as M E monomers, with 2-(4-methylphenyl)-1,3,2-dioxaphospholane and 2-(4-methylphenyl)-4-methyl-1,3,2-dioxaphospholane as M N monomers. The polymerizations proceeded without catalyst to give true alternating copolymers which were characterized by spectral and other methods.

Redox polymerization of acrylonitrile. Kinetics of the reaction initiated by systems based on cyanoacetic acid/Mn(III) complexes in dimethylsulphoxide

Abstract The kinetics of polymerization of acrylonitrile initiated by the redox systems cyanoacetic acid/Mn(OAc) 3 and cyanoacetic acid/tris(benzoylacetonato)manganese(III) in dimethylsulphoxide as solvent have been investigated over the range 20–35°. The kinetics of oxidation are consistent with the formation of intermediate complexes between the reactants, followed by electron transfer. Manganous ions inhibit the reaction by competitive complexation. The primary radicals are very efficient as initiators of polymerization which is terminated by mutual interaction of macroradicals. Mechanisms have been proposed to explain the kinetics; rate and equilibrium constants have been evaluated.

Synthesis and characterization of poly benzoylpropionamides

Abstract Linear polyamides having viscosities in the range of 0.12–0.41 dl/g have been prepared from bisbenzoyl propionic acids and aromatic diamines by low temperature solution polycondensation in 80–85% yield. Their solubility characteristics were studied in various solvents e.g. DMF, DMAC, HMPT, H2SO4. These polyamides are amorphous in nature; their densities range from 1.2 to 1.8 g/cm3. Their thermal properties were examined by TGA and DTA. The two stage decomposition phenomenon observed in TGA is in agreement with the DTA results. The integral procedural decomposition temperatures were calculated and found to exceed 250 in almost all cases.

Kinetics of oxidation of dimethyl sulphoxide by tervalent manganese

Kinetic evidence is presented for the reversible formation of a radical ion from Me2SO on oxidation by Mn3+, which initiates polymerisation of acrylonitrile that is terminated by the oxidant.