Free Radical Propagation Rate Coefficients of N-Containing Methacrylates: Are We Family?

Nitrogen-containing methacrylates are a highly interesting class of monomers, yet only very limited data exist describing their propagation rate coefficients, k p . Herein, we investigate the propagation behavior of three N-containing monomers, namely 2-( N, N -diethylamino)ethyl methacrylate (DEAEMA), 2-( N, N -dimethylamino)ethyl methacrylate (DMAEMA), and 3-( N, N -dimethylamino)propyl methacrylate (DMAPMAE), where we systematically vary the ester side chain with respect to spacer and branching length with the aim of establishing if all so far investigated N-containing methacrylates display family type behavior with regard to k p . Thus, the Mark–Houwink–Kuhn–Sakurada parameters alongside the Arrhenius parameters of k p were determined for these monomers via triple detection SEC and pulsed laser polymerization–size exclusion chromatography (PLP-SEC). The obtained data result in Arrhenius parameters for DEAEMA of A = 2.07 (−0.79 to +3.98) × 10 6 L mol –1 s –1 and E A = 20.45 (−2.02 to +2.28) kJ mol –1, for DMAEMA of A = 2.64 (−0.79 to +1.98) × 10 6 L mol –1 s –1 and E A = 20.71 (−1.31 to +1.32) kJ mol –1, and for DMAPMAE of A = 1.22 (−0.54 to +8.02) × 10 6 L mol –1 s –1 and E A = 19.59 (−2.74 to +3.83) kJ mol –1 . The data of the herein investigated monomers are critically compared to the previously published data of 2-( N -ethylanilino)ethyl methacrylate (NEAEMA), 2-(1-piperidyl)ethyl methacrylate (PipEMA), and 2-morpholinoethyl methacrylate (MOMA). It is found that DEAEMA and the previously investigated monomers can be described by one family, leading to a joint Arrhenius description for the four monomers NEAEMA, MOMA, PipEMA, and DEAEMA, best described by A = 1.55 (−0.57 to +3.88) × 10 6 L mol –1 s –1 and E A = 19.68 (−1.76 to +2.60) kJ mol –1 .