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Tunable adhesion of hydrogels

Abstract : The tunable adhesion of hydrogels on surfaces has systematically been studied by using specific and reversible polymer-polymer interactions. To this end, model surfaces of poly(acrylic acid) (PAA) brushes were obtained by "grafting to" and their structure, which is pH-sensitive, was characterized by neutron reflectivity. Meanwhile, neutral hydrogels of poly(N,N-dimethylacrylamide) (PDMA) and poly(acrylamide) (PAM) were synthesized by conventional radical polymerization, and their mechanical properties, their structure and their swelling were studied and varied by the means of two parameters: the initial swelling and the cross-linking density. In aqueous solution, the polymeric pairs of PAA and PDMA or PAA and PAM form interpolymer complexes. Their formation depends on pH and temperature and was studied by turbidimetry. Associations occur at low pH in both cases, and even if the two polymeric pairs are chemically similar, their complexations correspond to a standard UCST-type phase transition when the the proton acceptor is PAM but to an LCST-type transition with PDMA. The formation of these complexes in solution was also studied at the interfaces between the PAA brush and the PDMA and PAM hydrogels. The swelling behavior of the brush was investigated by neutron reflectivity: in the presence of the gel, the brush is additionally stretched in the presence of interactions at low pH and its structure remains unperturbed at high pH. A macroscopic study of these interactions at interfaces was carried out by the development of an experimental setup and protocols suitable for the quantitative measurement of the adhesion energy between immersed materials. Using a flat-flat contact test between the PAA brushes and PDMA and PAM gels covalently attached to substrates, an immersed and pH-tunable adhesion of the magnitude of thermodynamic adhesions has been demonstrated as well as the relatively slow kinetics involved in the formation and rupture of the interpolymer complexes at interfaces.
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Contributor : Ecole Espci Paristech <>
Submitted on : Monday, March 21, 2011 - 11:50:09 AM
Last modification on : Wednesday, October 14, 2020 - 3:43:07 AM

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  • HAL Id : pastel-00578517, version 1

Citation

Guillaume Sudre. Tunable adhesion of hydrogels. Chemical Physics [physics.chem-ph]. Université Pierre et Marie Curie - Paris VI, 2011. English. ⟨pastel-00578517⟩

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