ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Conformational energies of meso and racemic dyads of four alternating copolymers composed of methyl methacrylate or methyl acrylate with styrene or α-methylstyrene are computed by an empirical force field method as a function of the rotational angles about the skeletal bond pair within each of the dyads. The patterns of the energy contour surfaces of poly(methylacrylate-alt-styrene) and poly(methyl methacrylate-alt-α-methylstyrene) resemble respectively those of the corresponding homopolymers, i.e. poly(styrene) or poly(methyl acrylate) and poly(α-methylstyrene) or poly(methyl methacrylate). On the other hand the energy maps of poly(methyl methacrylate-alt-styrene) and poly(methyl acrylate-alt-α-methylstyrene) containing an α-methyl group in either of the monomeric units, greatly differ from those of the homopolymers of the component monomers. For all the alternating copolymers, the ḡ state is more than 5 kcal/mol higher in energy than the lowest energy state, as it was for the homopolymers. The cutoff distance, employed as a tentative measure of the solvent effect in the calculation of nonbonded interaction, gives a significant effect on the conformational energy, especially of the meso-tt state. Bond interaction parameters for various pairs of substitutents in the copolymers are evaluated from the calculation and they are compared with those determined from the conformational analysis of the homopolymers to check whether or not they are generally applicable to conformational analysis of polymers. Furthermore, conformational probabilities are calculated by the matrix method using the data of the energy calculation.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1981.021821129
