The performance of poly(styrene)-block-poly(2-vinyl pyridine)-block-poly(styrene) triblock copolymers as pH-driven actuators.

Poly(styrene)--poly(2-vinyl pyridine)--poly(styrene) (PS--P2VP--PS) triblock copolymers were synthesised by anionic polymerisation. Thick films were cast from solution and their structure analysed by small angle X-ray scattering (SAXS). Longer annealing times led to more ordered structures whereas short evaporation times effectively "lock" the polymer chains in a disordered state by vitrification. Well-ordered structures not only provide an isotropic network, which reduces localised stress within the material, but are also essential for fundamental studies of soft matter because their activity on the molecular scale must be analysed and understood prior to their use in technological applications. Well-characterised PS--P2VP--PS materials have been coupled to a pH-oscillating reaction and their potential application as responsive actuators is discussed.