The fabrication of macroporous polymer films with well-designed pore structures is challenging because of the lack of suitable templates and methods. Xiaoling Chen and Junqi Sun, Jilin University, Changchun, China, have developed a template-free method for the fabrication of closed honeycomb-like macroporous films. The films are prepared by exponential layer-by-layer (LbL) growth of polyelectrolyte films and subsequent two-step treatment with acidic solution and water.

In contrast to previous work, which utilized LbL-assembled ultrathin films with limited polyelectrolyte interpenetration for the fabrication of nanoporous and microporous films, this method can be used to assemble macroporous poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) films. The exponentially grown PAA/PAH films have thicknesses in the micrometer range and have highly interpenetrating film structure, which allows a large-scale phase separation to take place upon post-preparation treatment in acidic aqueous solution, thus producing macroporous films with closed honeycomb-like pores of several micrometers.

Due to their unique structures, these macroporous films are promising as highly responsive actuators, templates, and supports for guiding the deposition of advanced materials.

• Fabrication of Macroporous Films with Closed Honeycomb-Like Pores from Exponentially Growing Layer-by-Layer Assembled Polyelectrolyte Multilayers,
  Xiaoling Chen, Junqi Sun,
  Chem. Asian J. 2014.
  DOI: 10.1002/asia.201402054