Propagation rate coefficients of isobornyl acrylate, tert-butyl acrylate and 1-ethoxyethyl acrylate: A high frequency PLP-SEC study

Pulsed laser polymerization (PLP) coupled to size exclusion chromatography (SEC) is considered to be the most accurate and reliable technique for the determination of absolute propagation rate coefficients, k_p. Herein, k_p data as a function of temperature were determined via PLP-SEC for three acrylate monomers that are of particular synthetic interest (e.g., for the generation of amphiphilic block copolymers). The high-T_g monomer isobornyl acrylate (iBoA) as well as the precursor monomers for the synthesis of hydrophilic poly(acrylic acid), tert-butyl acrylate (tBuA), and 1-ethoxyethyl acrylate (EEA) were investigated with respect to their propagation rate coefficient in a wide temperature range. By application of a 500 H_z laser repetition rate, data could be obtained up to a temperature of 80 °C. To arrive at absolute values for k_p, the Mark-Houwink parameters of the polymers have been determined via on-line light scattering and viscosimetry measurements. These read: K = 5.00 × 10⁵ dL g^-1, α = 0.75 (piBoA), K = 19.7 × 10⁵ dL g^-1, a = 0.66 (ptBA) and K = 1.53 × 10⁵ dL g^-1, α = 0.85 (pEEA). The bulky iBoA monomer shows the lowest propagation rate coefficient among the three monomers, while EEA is the fastest. The activation energies and Arrhenius factors read: (iBoA): log(A/L mol^-1 s ^-1) = 7.05 and EA = 17.0 kJ mol^-1; (tBuA): log(A/L mol^-1 s^-1) = 7.28 and EA = 17.5 kJ mol^-1 and (EEA): log(A/L mol^-1 s^-1) = 6.80 and EA = 13.8 kJ mol ^-1.