Tuning Chiral Nematic Pitch of Bioresourced Photonic Films via Coupling Organic Acid Hydrolysis. Issue 7 (27th February 2019)

• Record Type: Journal Article
• Authors: Cheng, Zheng; Ye, Huilin; Cheng, Feng; Li, Hongyan; Ma, Yi; Zhang, Qing; Natan, Avi; Mukhopadhyay, Alolika; Jiao, Yucong; Li, Ying; Liu, Yongmin; Zhu, Hongli
• Is Part Of: Advanced materials interfaces. Volume 6:Issue 7(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-02-27
• Subjects: cellulose nanocrystal -- chiral nematic pitch -- coupled organic acid -- iridescent films -- molecular dynamic simulation -- self‐assembly; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.201802010
• Languages: English
• ISSNs: 2196-7350

Abstract

Abstract: Controlling the iridescent photonic film generated by self‐assembly of colorless cellulose nanocrystal (CNC) from the nanoscale to macroscale is challenging. This study combines experimental and computational approaches to systematically investigate the correlation between electrostatic interactions and chiral nematic structures. The chiral nematic order of the CNC colloidal is preserved in solid films after the evaporation of water. The cross‐sections of the iridescent film show a clear left‐handed helical arrangement of nanocrystals. The helical structure with the aid of acrylic acid exhibits longer organized patterns. This work reveals that compared to CNC prepared by pure sulfuric acid (zeta potential −37.1 mV), the CNC prepared using coupled mineral sulfuric and organic acrylic acid has a higher zeta potential (−67.2 mV), which induces the increase of helical pitch of the cholesteric nematic phase from 312 to 409 nm and a red shift of the iridescent film. Consequently, the tuning of reflected light wavelength lies in the variation of chiral nematic pitch inside the layered structure, which gives rise to different iridescent colors. The bioresourced photonic film is appealing to both academia and industry where optical and photonic components are essential. Abstract : In this study, sulfuric acid and acrylic acid are coupled to prepare cellulose nanocrystal (CNC) nematic film with larger helical pitch, resulting in redshift of iridescent. Furthermore, theoretical study of the correlation between the CNC repulsion force and pitch length is conducted. This work reveals that the surface charge of CNC is an important parameter to affect the iridescent color.