Thermoreversible Self-Assembly of Perfluorinated Core-Coronas Cellulose-Nanoparticles in Dry State

Abstract

Self-assembly of nanoparticles (NPs) forming unique structures has been investigated extensively over the past few years. However, many self-assembled structures by NPs are irreversible, because they are generally constructed using their suspensions. It is still challenging for NPs to reversibly self-assemble in dry state, let alone of polymeric NPs with general sizes of hundreds of nm. Herein, this study reports a new reversible self-assembly phenomenon of NPs in dry state, forming thermoreversible strip-like supermolecular structures. These novel NPs of around 150 nm are perfluorinated surface-undecenoated cellulose nanoparticles (FSU-CNPs) with a core-coronas structure. The thermoreversible self-assembled structure is formed after drying in the air at the interface between FSU-CNP films and Teflon substrates. Remarkably, the formation and dissociation of this assembled structure are accompanied by a reversible conversion of the surface hydrophobicity, film transparency, and anisotropic properties. These findings show novel feasibility of reversible self-assembly of NPs in dry state, and thereby expand our knowledge of self-assembly phenomenon.

Remarkable thermoreversible self-assembled structures from perfluorinated surface-undecenoated cellulose nanoparticles (FSU-CNPs) with core-coronas structure were formed on the surfaces of self-standing films in dry state. The thermoreversible properties including morphology, birefringence, wetting ability ,and transparency can be mutually transformed in dry state via heating at high temperature, such as at 80 °C, and cooling with aging at room temperature.

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