Novel pH- and thermoresponsive amphiphilic diblock copolymer, comprising hydrophilic poly­(2-dimethyl­aminoethyl acrylate) (PDMAEA) and amphiphilic poly­(styrene-grad-2-dimethyl­aminoethyl acrylate) (P­(S-grad-DMAEA)) blocks, was synthesized by nitroxide-mediated radical polymerization. A series of copolymers (PS-grad-PDMAEA) with controlled molar masses and low dispersities over a wide range of monomer feed ratios (0 < f S,0 < 1) were synthesized. Both conventional linearization and nonlinear least-squares methods were applied to estimate reliable values of the reactivity ratios for S and DMAEA radical polymerization. The calculated values of the reactivity ratios (r DMAEA = 0.25 and r S = 1.15) perfectly fitted the drift in monomer feed ratio versus conversion, showing a gradient distribution along the copolymer chains. The self-assembling behavior of the copolymers in the aqueous medium was investigated by dynamic light scattering and small-angle neutron scattering over a wide range of pH, temperature, and salt concentration. These block-gradient copolymers show reversible self-association into micelle-like structure (D h ∼ 20 nm) in aqueous solutions triggered by both pH and temperature.

Evidence is presented that shows Lewis acid-surfactant complex catalyzed polymerization proceeds via a radical, not a cationic, mechanism.

pinene is a well-known bio-based monomer that can be polymerized via cationic polymerization to give low molecular weight resins that find use commercially as tackifiers. However, the controlled synthesis of these polymers by cationic polymerization is challenging due to the reactivity of commonly used Lewis acid catalysts and the propagating carbocationic species with water. Here, the cationic polymerization of -pinene under mild conditions using the water stable Lewis acid tris(pentafluorophenyl)borane is demonstrated. It is shown that when combined with a suitable alcohol initiator the molecular weight of the polymer can be tuned while the kinetics are largely controlled by the concentration of tris(pentafluorophenyl)borane. The final poly( -pinene) is shown to perform well as a tackifier in the formation of pressure sensitive adhesives based on polystyrene-b-polyisoprene-b-polystyrene triblock copolymers.

When applied to the cationic polymerization of styrene, thiocarbonylthio compounds can lead to a dual control mechanism, where degenerative chain transfer occurs concurrent with a reversible addition mechanism.