Stimuli-responsive polymers – be the stimulus light, temperature, or pH – rely on activatable functional monomers to work. However, fast and complete transduction of molecular changes to tuning macroscopic properties remains a challenge.

Xian Jun Loh, Institute of Materials Research and Engineering and National University of Singapore, and colleagues have developed a dual responsive polymer gelator by incorporating both light-responsive spiropyran and heat-responsive poly(propylene glycol) units into a copolymer backbone. The aqueous solution of the polymer can undergo fast and reversible sol-to-gel conversion by either photoirradiation or heating, accompanied by up to three orders of magnitude change in storage modulus.

This study presents an interesting polymer that may find application, e.g., in multicontrol 3D printing or smart molding and casting. The design principle could also inspire the development of other dual- or multi-responsive materials.

• Dual-responsive reversible photo/thermogelling polymers exhibiting high modulus change,
  Qingqing Dou, Sing Shy Liow, Wengui Weng, Xian Jun Loh,
  J. Polym. Sci. Part A: Polym. Chem. 2016.
  DOI: 10.1002/pola.28191