Particle Adsorption on Hydrogel Surfaces in Aqueous Media due to van der Waals Attraction

Abstract

Particle adhesion onto hydrogels has recently attracted considerable attention because of the potential biomedical applications of the resultant materials. A variety of interactions have been taken advantage of for adsorption, including electrostatic forces, hydrophobic interactions and hydrogen bonding. In this study, we report significant adsorption of submicron-sized silica particles onto hydrogel surfaces in water, purely by van der Waals (vdW) attraction. The vdW forces enabled strong adhesions between dielectric materials in air. However, because the Hamaker constant decreases in water typically by a factor of approximately 1/100, it is not clear whether vdW attraction is the major driving force in aqueous settings. We investigated the adsorption of silica particles (diameter = 25–600 nm) on poly(acrylamide) and poly(dimethylacrylamide) gels using optical microscopy, under conditions where chemical and electrostatic adsorption is negligible. The quantity of adsorbed particles decreased on decreasing the Hamaker constant by varying the refractive indices of the particles and medium (ethyleneglycol/water), indicating that the adsorption is because of the vdW forces. The adsorption isotherm was discussed based on the adhesive contact model in consideration of the deformation of the gel surface. The present findings will advance the elucidation and development of adsorption in various types of soft materials.

Preparation of polymer gold nanoparticle composites with tunable plasmon coupling and their application as SERS substrates

“…These NP loadings represent an average PS surface area coverage of 4.1 % (PSLA1) and 20 % (PSLA4). The value for the maximum loaded 17 nm AuNP@PSLA4 is typical for electrostatically stabilised AuNPs (<30 %) due to Coulomb repulsions 19,43,60 and is in agreement with our previously reported values for AuNPs immobilised onto amine-modified PS beads. 14 Similar degrees of coverage (3-23 %) were determined for the other NP sizes, see ESI, Table S3.…”

Construction of heparin-based hydrogel incorporated with Cu5.4O ultrasmall nanozymes for wound healing and inflammation inhibition

“…S 3E). Therefore, it may be that the Cu 5.4 O USNPs are bound to Hep-PEG gels via coordination and physical adsorption interactions (such as van der Waals and hydrogen-bonding interactions) [ [44] , [45] , [46] ]. The coordination process involves the lone-pair electrons of N being transferred to vacant orbitals on Cu, thus forming N-Cu coordination bonds [ 43 ].…”

Bi-functional silica nanoparticles for simultaneous enhancement of mechanical strength and swelling capacity of hydrogels

“…Weak hydrogen bonding or hydrophobic interaction of PAm polymer and the surface of BF-Si crosslinker may be responsible for this kind of temporary interaction. 50 Many applications of hydrogels like chromatographic packaging and controlled drug release require high swelling capacity in aqueous solution without compromising on the mechanical integrity of the polymeric network. 51 To investigate the swelling capacity of the BF-Si crosslinked hydrogels the swelling ratio of PAc-Si-0.05% and PAm-Si-0.05% hydrogels were examined at different time intervals aer immersing in large amount water at pH 7.…”