The effect of nanoconfinement on the free radical polymerization of dodecyl methacrylate (DMA) with di-tert-butyl peroxide (DtBP) initiator is investigated over a wide temperature range from 110 to 190 °C using differential scanning calorimetry. The reaction shows a distinct induction time, which decreases as temperature increases, with an activation energy that is the same, albeit, of opposite sign, as that for dissociation of the initiator. The rate of reaction increases with increasing temperature and is higher in nanopores than in bulk conditions, with an Arrhenius temperature dependence at temperatures lower than 160 °C and an activation energy that is approximately 10% lower in the nanoconfined cases than for bulk. The higher reaction rate and lower activation energies in the nanopores are presumably due to specific interactions between the monomer and the native silanol groups on the pore surface. The enhancement of the reaction rate is found to be inversely related to the length of the alkyl group and the water contact angle comparerd data for several poly(n-alkyl methacrylate) studied previously. For bulk and nanoconfined DMA polymerizations, the molar mass increases as temperature decreases with a cross-linked product obtained at temperatures below 170 °C. The gel fraction increases as temperature decreases and is nearly 80% at 110 °C. In the nanopores, the molar mass is smaller compared to that in bulk conditions at high temperatures. The results can be described by a simplified recursive model.