SYNTHESIS AND CHARACTERIZATION OF 3-ARYL-2-(POLYSTYRYL)CYCLOPROPENONES VIA CYCLOPROPENIUM ION SUBSTITUTION ON POLYSTYRENE

Electrophilic substitution of cyclopropenium ions on aromatic polymers offers a unique opportunity to introduce polar functionality in a con trolled manner to conventional, nonpolar polymers. Phenylcyclopropenon e substituted polystyrene with predictable chemical composition and na rrow molecular weight distribution were prepared. Size exclusion chrom atography (SEC) analysis demonstrated the absence of branching or cros slinking in these functionalized polystyrenes during electrophilic sub stitution of the parent homopolymer. C-13-NMR confirmed that the degre e of phenylcyclopropenone substitution was both highly efficient and p redictable over a broad compositional range. The glass transition temp erature (T(g)) of the polymers was found to vary linearly with mole % phenylcyclopropenone substitution of the polystyrene. Thermal gravimet ric analysis (TGA) indicated that thermal decarbonylation of the appen ded cyclopropenones occurred at approximately 180-degrees-C. Weight lo ss vs. temperature profiles correlated reasonably well with levels of substitution based on C-13-NMR analysis, confirming that decarbonylati on of the calculated cyclopropenone substituents was the predominant t hermal decomposition pathway. (C) 1995 John Wiley & Sons, Inc.