Abstract
High-molecular weight phenol novolak resins (RN) and o-cresol novolak resins (oCR) were prepared in organic solvent. The molecular structure was determined by 13C-NMR measurements and computer simulation technique with a percolation model. It was found that RN was a branched polymer and a microgel formation was observed, arising from intramolecular reaction (cyclization). The solution properties of acetylated RN (Ac-RN) and acetylated oCR (Ac-oCR) were determined in good solvent and θ-solvent. Ac-RN behaved as a branched polymer. On the other hand, Ac-oCR showed linear polymeric properties, but Ac-oCR chain was more shrinkable and compact in θ-solvent than polystyrene, which is a typical linear polymer. The properties of high-molecular weight phenolic resins suppose to depend on the main chain structure composed from phenolic ring and methylene linkages. Phenolic cyclic oligomers can be readily formed due to this structural feature. New properties on the basis of the phenolic resin skeleton will be born by controlling reactivity of phenols.
