The influences of silanes on interfacial adhesion and surface properties of nanocellulose film coating on glass and aluminum substrates

Abstract Nanocellulose is a natural polymer containing abundant hydroxyl groups which can create the network of hydrogen bonds between intra- and inter-molecular cellulose chains and also react with many other functional molecules. These interactions are helpful to film formation and surface modification. Silylation is a well-known modification, in which silane is substituted into a molecule for the improvement of desired properties such as hydrophobization, antimicrobial activity, and compatibilization with plastics for composites. However, to our knowledge, there is no study regarding the silane-modified nanocellulose for adhesion improvement even though nanocellulose film has potential for applications as a protective coating, insulation coating, biomedical coating, etc. Therefore, in this work nanofibrillated cellulose in aqueous suspension - obtained from hemp stubs - was used as a coating material. Various silanes containing dissimilar functional groups were employed in order to improve poor adhesion of nanocellulose films on glass and aluminum substrates and also enhance their physical and mechanical properties. It was found that silane containing an amino group provided the optimum increase of adhesion performance when compared with epoxy and methacryloxy groups, in which higher ratio of amino silane tended to give better adhesion on glass and aluminum substrates. Moreover, amino silane was capable of improving surface hardness, elastic modulus, and scratch resistance of coating film and also providing the satisfied results of optical properties and hydrophobic characteristic to nanocellulose film.

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