Parag G. Mehta

Polyesters with controlled thermal decomposition

Abstract Two main-chain rigid-rod-like polyesters containing pendent t-butyl ester groups were synthesized. Simultaneous thermogravimetric analysis and Fourier-transform infra-red spectroscopy were applied to monitor the formation of isobutylene as well as other gaseous products that evolved at elevated temperatures. The polymers were also characterized by microscopy, differential scanning calorimetry and infra-red spectroscopy before and after thermal treatment.

Control of Chromophore Length in Electroluminescent Polymers. Part II. Mainchain Polymers

Abstract Electroluminescence emission has been demonstrated in mainchain polyesters and a structurally analogous polyamide. High molecular weight polyesters were synthesized by condensation of a dihydroxy functionalized, substituted, phenylene vinylene analogue, e.g., the lumo-phore, with a variety of dicarboxylic acid chlorides. The structure and hence the conjugation length of the emitting comonomer was predetermined prior to polymerization. Since the diacid moieties did not contribute to the conjugation length and hence the emission wavelength, the structure of the diacid was determined on the basis of its ease of synthesis, reactivity, and solubilizing ability in the final polymer. In each of the polyesters the electroluminescence wavelength of light-emitting diodes made from these polymers was similar to their photoluminescence emission spectrum in solution and the solid state at room temperature. The emission wavelengths ranged from blue to green. The polyamide exhibits a very broad band, nearly whi...

A Novel Synthesis of Squaric Acid Esters

Abstract A new procedure for the synthesis of the benzylic ester of the squaric acid is described. A first example of the reaction silyl ‘enol ether’ of the squaric acid with an electrophile in the...