title: Cellulose Nanocrystal/Poly(ethylene glycol) Composite as an Iridescent Coating on Polymer Substrates: Structure-Color and Interface Adhesion.
abstract: The broad utility as an environmentally friendly and colorful coating of cellulose nanocrystal (CNC) was limited by its instability of coloration, brittleness, and lack of adhesion to a hydrophobic surface. In the present work, a neutral polymer, poly(ethylene glycol) (PEG) was introduced into CNC coatings through evaporation-induced self-assembly (EISA) on polymer matrices. The structure-color and mechanical properties of the composite coating or coating film were characterized by UV-vis spectroscopy, polarized light microscopy (PLM), scanning electron microscopy (SEM), wide-angle X-ray diffraction (WXRD), and tensile tests. Results showed that the reflective wavelength of the iridescent CNCs could be finely tuned by incorporation of PEG with varied loadings from 2.5 to 50 wt %, although the high loading content of PEG would produce some side effects because of the severe microphase separation. Second, PEG played an effective plasticizer to improve the ductility or flexibility of the CNC coating or coating film. Furthermore, as a compatibilizer, PEG could effectively and tremendously enhance the adhesion strength between CNCs and neutral polymer matrices without destroying the chiral nematic mesophases of CNCs. Environmentally friendly CNC/PEG composites with tunable iridescence, good flexibility, and high bonding strength to hydrophobic polymer matrices are expected to be promising candidates in the modern green paint industry.
authors.affiliation: Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science and Technology , Nanjing 210044, P. R. China.
authors.forename: Mingyue
authors.initials: M
authors.lastname: Gu
authors.affiliation: Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science and Technology , Nanjing 210044, P. R. China.
authors.forename: Chenyu
authors.initials: C
authors.lastname: Jiang
authors.affiliation: Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science and Technology , Nanjing 210044, P. R. China.|Department of Physics, University of Colorado , Boulder, Colorado 80309, United States.
authors.forename: Dagang
authors.initials: D
authors.lastname: Liu
authors.affiliation: Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science and Technology , Nanjing 210044, P. R. China.
authors.forename: Nana
authors.initials: N
authors.lastname: Prempeh
authors.affiliation: Department of Physics, University of Colorado , Boulder, Colorado 80309, United States.
authors.forename: Ivan I
authors.initials: II
authors.lastname: Smalyukh
keywords: cellulose nanocrystal; cholesteric liquid crystal; interface adhesion; iridescent coatings; poly(ethylene glycol); polymer substrate