title: Influence of drying time of polyelectrolyte multilayers on the compression-induced pattern formation.
abstract: Compression of the polyelectrolyte multilayers has been found previously when they were pressed by a poly(dimethylsiloxane) (PDMS) stamp under a small pressure (Macromolecules 2004, 37, 8836). In this work, we further found that the pattern formation of the poly(diallyldimethylammonium chloride) (PDADMAC) containing multilayers is dependent on the drying time of the multilayers prior to compression. After the poly(4-styrenesulfonic acid-co-maleic acid) sodium salt (PSSMA)/PDADMAC multilayers were dried at 70% relative humidity and room temperature for 2, 6, and 12 h, compression of the multilayers by a PDMS stamp with linear patterns obtained double strips, high ridges and linear patterns on the multilayers, respectively. These phenomena were independent of the layer number and salt concentration and could be applied to other PDADMAC containing multilayer systems such as poly(styrene sulfonate) sodium salt (PSS)/PDADMAC and poly(acrylic acid, sodium salt) (PAA)/PDADMAC. A model was suggested to depict the process, and the influence of the water content on the multilayer structure and properties was discussed. The stability experiments revealed that the strips and high ridges obtained at shorter drying time could be erased by incubation in water for 5 h, while the compression created patterns were very stable.
authors.affiliation: Key Laboratory of Macromolecular Synthesis and Functionalization, Ministry of Education, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Gong
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.forename: Lulu
authors.initials: L
authors.lastname: Han
authors.forename: Changyou
authors.initials: C
authors.lastname: Gao