Small molecule surfactants are known to self-assemble to produce anisotropic worm-like nano-structures under certain conditions. Aqueous solutions of these micelles exhibit interesting gel properties due to inter-worm entanglements including high viscosity, shear-thinning and stimulus response. This has led to a range of technological applications such as enhanced oil recovery, drag reduction agents and personal care thickeners.
Polymer Centre Director, Steve Armes, and co-workers have recently reported on less common themo-responsive polymer based worms. Diblock copolymers were prepared via aqueous dispersion polymerization. Careful control of the diblock composition enabled worms to be generated reproducibly. These worms form soft free-standing gels in aqueous solution.
Below a critical temperature, the material de-gels to form a free flowing liquid due to the worms reorganising to form spheres; the process is reversible and relatively insensitive to concentration. This critical gelation temperature can be tuned by altering the length of one of the copolymer components. It is anticipated that these materials will have biomedical applications.