PREPARATION AND PROPERTIES OF UV-AUTOCURABLE BTDA-BASED POLYESTER MULTIACRYLATES .1. EFFECTS OF ACRYLIC FUNCTIONALITY AND POLYOL MOLECULAR-WEIGHT

A series of UV‐autocurable benzophenone tetracarboxylic dianhydride (BTDA)‐based polyester multiacrylate oligomers was synthesized and the effects of acrylic functionality and molecular weight on their physical properties were investigated. The multiacrylate oligomers were prepared by the ring‐opening reaction of glycidyl methacrylate and diacrylate oligomers containing pendant acid groups. The latter was prepared from BTDA, PEG, and hydroxyethyl acrylate (HEA). The obtained autocurable oligomers are cured rapidly when exposed to ultraviolet (UV) without the addition of photoinitiator or photosensitizer. Increasing the mole percentage of GMA in oligomer led to higher acrylic functionality and photocuring rate. The increasing in the functionality of acrylic oligomer was reflected in higher crosslinking density of the cured film which resulted in an increase in Young's modulus and breaking strength, while elongation at break decreased. On the other hand, increasing PEG molecular weight led to a decrease in Young's modulus and breaking strength due to existence of a small amount of acrylate phase and a larger chain length between crosslinks. The dynamic mechanical analysis results showed that storage modulus (E') and glass transition temperature (Tg) were affected by the mol % of GMA and the molecular weight of PEG in the cured oligomers. With increasing mol % of GMA in the oligomers, the storage modulus and Tg shifted to higher temperatures; however, storage modulus and Tg decreased with increasing PEG molecular weight. Copyright © 1990 John Wiley & Sons, Inc.