EFFECT OF TACTICITY ON CONFORMATION OF P-TERT-BUTHLPHENOL ACETALDEHYDE RESINS AS STUDIED BY MOLECULAR SIMULATION

p-tert-Butylphenol acetaldehyde resins can have isotactic, syndiotacti c, and atactic sequences. Structural characteristics of the p-tert-but ylphenol acetaldehyde resin with different tacticities were studied us ing molecular mechanics and molecular dynamics. Trimer-decamer isotact ic and syndiotactic resins and 12 stereoisomers of a hexamer were calc ulated. In the p-tert-butylphenol acetaldehyde resin, the hydroxyl gro ups cluster in the center of the molecule through intramolecular hydro gen bonding and the tert-butyl groups are extended out. It has been fo und that the energy-minimized structures of the isotactic resin are mo re stable than those of the syndiotactic resin by 7-17 kcal/mol. From the results of molecular dynamics at 303, 373, 474, and 573 K for 300 ps, the isotactic resin was also found to be more stable than the synd iotactic resin. For atactic resins, the closer to isotactic their stru ctures are, the more stable they are. (C) 1998 John Wiley & Sons, Inc.