We have synthesized two methyl 4'-(omega-alkenoxy)-4-biphenylcarboxylates and two methyl 6-(omega-alkenoxy)-2-naphthalenecarboxylates and used them as reactive diluents in the crosslinking of vinyl-terminated side-chain liquid-crystal polyepichlorohydrin derivatives containing analogous mesogenic moieties. The crosslinking was done with a 10 mol% of a free radical initiator system. Differential scanning calorimetry, polarized optical microscopy and X-ray diffraction measurements show that the mixtures of polymers with the reactive diluents had the same mesophases as pure polymers. We obtained liquid crystal thermosets from the biphenyl derivatives but, because of the low isotropization temperatures of the polymer-diluent mixtures, the naphthalene derivatives did not produce crosslinked anisotropic materials.