Stability of polyelectrolyte multilayer micropatterns in response to post-treatments

Post-treatments of the micro-molded poly(4-styrenesulfonic acid-co-maleic acid, 1:1 SS:MA) sodium salt (PSSMA)/poly(diallyldimethylammonium chloride) (PDADMAC) multilayers in water or at elevated temperature were conducted to disclose the stability and transformation of patterns prepared at different conditions. The compression induced patterns kept unchanged regardless of the incubation time, while the lateral flow induced patterns disappeared rapidly within 10 min in water. Results showed that the pattern disappearance was not caused by the remodeling or swelling of the multilayers, but caused by mass loss of the uncompressed region. Heat treatment of the high ridge patterns could greatly decrease their height and stabilize the pattern structure. The double strip patterns could be transformed to the high ridge patterns and the linear patterns by annealing at 70 °C for 3 h and 6 h, respectively. Therefore, the pattern features and stability against water etching can be effectively modulated by the post-treatment time at elevated temperature.

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► Alteration kinetics of pattern compressed films as a function of post treatment time in water.
► Demonstrate the heat treatment could greatly decrease the height of high ridges and stabilize the pattern structure.
► Demonstrate that the pattern height decrease is caused by erasure of the uncompressed region.
► Demonstrate the double strips pattern can be transformed to the state of high ridge pattern by post annealing.