Robust and Tailored Wet Adhesion in Biopolymer Thin
Films
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Abstract
Model layer-by-layer (LbL) assemblies
of poly(allylamine hydrochloride)
(PAH) and hyaluronic acid (HA) were fabricated in order to study their
wet adhesive behavior. The film characteristics were investigated
to understand the inherent structures during the assembly process.
Subsequently, the adhesion of these systems was evaluated to understand
the correlation between the structure of the film and the energy required
to separate these LbL assemblies. We describe how the conditions of
the LbL fabrication can be utilized to control the adhesion between
films. The characteristics of the film formation are examined in the
absence and presence of salt during the film formation. The dependence
on contact time and LbL film thickness on the critical pull-off force
and work of adhesion are discussed. Specifically, by introducing sodium
chloride (NaCl) in the assembly process, the pull-off forces can be
increased by a factor of 10 and the work of adhesion by 2 orders of
magnitude. Adjusting both the contact time and the film thickness
enables control of the adhesive properties within these limits. Based
on these results, we discuss how the fabrication procedure can create
tailored adhesive interfaces with properties surpassing analogous
systems found in nature