Pulsed‐laser radical polymerization and propagation kinetic parameters of some alkyl acrylates

Pulsed‐laser photoinitiated polymerization was used to determine, in toluene solution, the propagation kinetic parameters of a series of acrylates with increasing size of the alkyl side group. Transfer to monomer and to toluene did not occur significantly in our PLP conditions and our temperature range since no broadening of the MMD was observed, allowing generally to work with two inflection points. In contrast, depending on the nature of the acrylate and on the PLP conditions, transfer to polymer, and thus long chain branching, can critically interfere. Indeed, the Mark‐Houwink‐Sakurada parameters, which are used to calculate the absolute molar mass at the inflection point, strongly depend on the polymer structure and thus, should be carefully measured for each PLP sample. Although still preliminary, the results show that the k_ps measured in toluene solution present a tendency to continuously decrease when increasing the size of the side group. This observation is conflicting with the reported behaviour for PLP experiments in bulk, revealing a possible solvent effect.     

The use of selected acrylate and acrylamide-based surfmers and polysoaps in the emulsion polymerization of styrene

Polymerizable surfactants (surfmers) 12-acryloyloxy-dodecanoic acid and 11-acrylamidoundecanoic acid and their respective sodium salts were prepared and then polymerized to form their corresponding oligomers using reversible addition-fragmentation chain transfer (RAFT). Different concentrations of both the surfmers, their sodium salts, and their RAFT oligomers were used as polysoaps in the emulsion polymerization of styrene. Stabilities of the pre-emulsions before polymerization were determined and compared. After polymerization, particle sizes and polydispersities of the resulting polystyrene latices were determined. Sodium dodecyl sulfate (SDS) was used as a reference surfactant to compare the particle sizes and stabilities of the pre-emulsions prepared using surfmers and polymeric surfactants (polysoaps) as particle stabilizers. Emulsion polymerization of styrene using these surfmers and polysoaps all led to latices which were stable for a period of more than six months, as indicated by constant particle sizes, whereas latices prepared using the conventional surfactant, SDS, were not as stable.