Abstract: | Cross-polarization magic-angle-spinning 13C-NMR spectra of polystyrenes crosslinked with 1–20% of methine vinyl carbon 13C-labeled p-divinylbenzene and of Friedel–Crafts crosslinked poly(chloromethylstyrene)s have been obtained with both glossy solid and CDCl3-swollen gel samples. The spectra of natural abundance, uncrosslinked, glassy polystyrene, and the spectra of the solid labeled networks give aliphatic and aromatic peak areas only 0.7 times as large per 13C atom as that of poly(oxymethylene). Similarly the crosslinked poly(chloromethylstyrene) gave peak areas about 0.6 times that of internal poly(oxymethylene). The labeled gels give peak areas 0.2–0.6 times as large per 13C atom as glassy polystyrene, and the peak areas in spectra of gels increase with the divinylbenzene content |