Force‐Free Patterning of Polyelectrolyte Multilayers under Solvent Assistance

Abstract

Physical patterns were created on hydrated PSS/PDADMAC multilayers without using external force. A typical process was to put a PDMS stamp onto the wet and swollen multilayers, which were then put into an oven and maintained for a period of time to micromold the multilayers. The influence of molding temperature and time, multilayer thickness, solvent quality, and multilayer compositions on pattern formation were elucidated. Evolution of the patterns from double lines, double strips, and meniscus‐shaped ridges to high ridges was observed under all conditions, revealing that this is a universal principle for this process. Finally, patterns on PAA/PAH and PSS/PAH multilayers were also prepared at the optimal conditions, highlighting its wide generality on the multilayer patterning.

Influences of surface chemistry and swelling of salt-treated polyelectrolyte multilayers on migration of smooth muscle cells

“…The dry thicknesses of the multilayers treated with 1, 2, 3, 4 and 5 M NaCl solutions measured by ellipsometry were 182, 172, 142, 89 and 30 nm, respectively. The thickness in air was confirmed further by atomic force microscopy, verifying the accuracy of the ellipsometry data [41]. Therefore, significant mass loss occurred along with the increase in NaCl concentrations.…”

Modulating the Structure and Properties of Poly(sodium 4-styrenesulfonate)/Poly(diallyldimethylammonium chloride) Multilayers with Concentrated Salt Solutions

“…This huge mass loss (>70%) is much larger than that of the PAA/ PAH (∼50%) and PSS/PAH multilayers (∼15%) treated in the same 5 M salt solution 45 because of the weaker interaction. 46,54 By applying the salt treatment to PSS-terminated multilayers (i.e., (PSS/PDADMAC) 7 PSS), we obtained a similar result. The film surface was dominated by PSS, with an S/N ratio of 61:39, which was decreased to 53:67 and 47:53 after treatment with 1 and 2 M NaCl solutions, respectively.…”

“…Nonetheless, the chemical composition of the PAA/PAH multilayers remained constant as a result of a similar extent of PAA and PAH release. Compared to those PAH/PAA and PSS/PAH polyelectrolyte pairs, the interaction between PSS/PDADMAC polyelectrolytes pairs is weaker, , leading to the change in the chemical compositions and thereby the physicochemical properties as demonstrated in this study.…”

“…All of the results are in good agreement with the fact that the outmost layer is first removed, resulting in the increasing S/N ratio, and then the bulk of the multilayers is exposed and broken sharply along with the increase in salt concentration, leading to 43 and 72% mass losses in multilayers 4 and 5 M, respectively. This huge mass loss (>70%) is much larger than that of the PAA/PAH (∼50%) and PSS/PAH multilayers (∼15%) treated in the same 5 M salt solution because of the weaker interaction. , …”

Shape Deformation and Recovery of Multilayer Microcapsules after Being Squeezed through a Microchannel

“…26 However, when the deformation extent is pretty large such as 34%, the invagination degree exceeds the limit that the bending energy can recover, leading to permanent physical deformation. It is worth mentioning that, unlike the PDADMAC/PSS counterpart, the PAH/PSS multilayers are very difficult to be compressed, 27 implying that the overall surface area of the PAH/PSS capsules should be kept during the deformation and recovery processes. Furthermore, the time required for the capsules to pass through ∼100 μm distance in the constriction (schematically shown in the bottom of Figure 1b) was quantitatively measured.…”