Abstract
This study investigates flexible (polyamide 6.6 PA-6.6, polyethylene terephthalate PET, Cu, Al, and Ni foils) and, for comparison, stiff substrates (silicon wafers and glass) differing in, for example, in surface free energy and surface roughness and their ability to host cellulose-based thin films. Trimethylsilyl cellulose (TMSC), a hydrophobic acid-labile cellulose derivative, was deposited on these substrates and subjected to spin coating. For all the synthetic polymer and metal substrates, rather homogenous films were obtained, where the thickness and the roughness of the films correlated with the substrate roughness and its surface free energy. A particular case was the TMSC layer on the copper foil, which exhibited superhydrophobicity caused by the microstructuring of the copper substrate. After the investigation of TMSC film formation, the conversion to cellulose using acidic vapors of HCl was attempted. While for the polymer foils, as well as for glass and silicon, rather homogenous and smooth cellulose films were obtained, for the metal foils, there is a competing reaction between the formation of metal chlorides and the generation of cellulose. We observed particles corresponding to the metal chlorides, while we could not detect any cellulose thin films after HCl treatment of the metal foils as proven by cross-section imaging using scanning electron microscopy (SEM).
Highlights
In industry, the modification of different types of surfaces is a crucial aspect in materials design and development
We explore various substrates which impose challenges in the preparation of cellulose thin films due to the topology, surface free energy, chemical sensitivity towards the regeneration procedure, and flexibility/bendability of the substrate
The first challenge to overcome in the modification of metal foils and polymer films featuring several micrometers of thickness is their intrinsic flexibility, which principally impedes the formation of homogenous films by spin coating; a phenomenon that scales with the size of the substrates
Summary
The modification of different types of surfaces is a crucial aspect in materials design and development. The major biopolymer on earth, has not been extensively investigated in this context [4,5,6,7,8]. This originates from the inherent insolubility of cellulose in common organic solvents, which often makes direct processing into thin films tedious [9,10,11,12]. At high degree of substitution with trimethylsilyl groups (DSTMS ), TMSC has good solubility in organic solvents (e.g., CHCl3 ) and homogenous films can be produced by spin coating or Langmuir Schaefer deposition [14,17]. After the Materials 2018, 11, 2433; doi:10.3390/ma11122433 www.mdpi.com/journal/materials
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
