SPECTROSCOPIC STUDY OF SOLID-STATE PHOTOREACTION IN ORGANIC-CRYSTAL - PHOTOPOLYMERIZATION OF DIMETHYL ESTER OF ALPHA,ALPHA'-DICYANO-PARA-PHENYLENEDIACRYLIC ACID AND DIETHYL ESTER OF PARA-PHENYLENEDIACRYLIC ACID

Raman spectroscopy has been used to study solid-state photopolymerization reactions in dimethyl ester of alpha,alpha'-dicyano-p-phenylenediacrylic acid (p-CPAMe) and diethyl ester of p-phenylenediacrylic acid (p-PDAEt). The reactants and products were characterized by infrared and Raman spectroscopy. Excitation and emission spectra suggest that in p-CPAMe exciton-phonon coupling is strong, but in the other monomer it is very weak. Raman phonon spectroscopic study reveal that in both the samples the reaction mechanism is homogeneous in the initial stages. However, in the later stages the reaction becomes heterogeneous in p-PDAEt. In p-CPAMe the lattice becomes disordered with the progress of polymerization and finally becomes amorphous whereas in p-PDAEt the lattice remains highly ordered.