Solvent Effects on Acrylate k sub(p) in Organic Media?-A Systematic PLP-SEC Study

• Published in: Macromolecular rapid communications. Vol. 35; no. 23; pp. 2029 - 2037
• Main Authors: Haehnel, Alexander P, Wenn, Benjamin, Kockler, Katrin, Bantle, Tobias, Misske, Andrea M, Fleischhaker, Friederike, Junkers, Thomas, Barner-Kowollik, Christopher
• Format: Journal Article
• Language: English
• Published: 01.12.2014
• Subjects: Acetates; Acrylates; Alkyl acrylates; Chains; Esters; Solvent effect; Solvents; Toluene
• ISSN: 1022-1336; 1521-3927
• DOI: 10.1002/marc.201400479

The Arrhenius parameters of the propagation rate coefficient, k sub(p), are determined employing high-frequency pulsed laser polymerization-size exclusion chromatography (PLP-SEC) for the homologous series of five linear alkyl acrylates (i.e., methyl acrylate (MA), butyl acrylate (BA), dodecyl acrylate (DA), stearyl acrylate (SA), and behenyl acrylate (BeA)) in 1 m solution in butyl acetate (BuAc) as well as in toluene. The comparison of the obtained k sub(p) values with the literature known values for bulk demonstrates that no significant solvent influence neither in BuAc nor in toluene on the propagation reaction compared to bulk is detectable. Concomitantly, the k sub(p) values in toluene and in BuAc solution display a similar increase with increasing number of C-atoms in the ester side chain as was previously reported for the bulk systems. These findings are in clear contrast to earlier studies, which report a decrease of k sub(p) with increasing ester side chain length in toluene. The additional investigation of the longest and shortest ester side chain acrylate (i.e., BeA and MA) over the entire experimentally available concentration range at one temperature (i.e., 50 degree C) does not reveal any general concentration dependence and all observed differences in the k sub(p) are within the experimental error. The solvent dependence of the FRP propagation reaction is probed by examining solutions of linear acrylates in butyl acetate and toluene in comparison to bulk. In contrast to previous reports (and aqueous systems), no solvent effects are detectable. Instead-for the first time-a correlation between the Arrhenius parameters and ester side chain length is observed.