Shape Memory Cellulose-Based Photonic Reflectors

Abstract

Bio-polymer based composites enable to combine different functionalities using renewable materials and cost-effective routes. Here we fabricate novel thermoresponsive photonic films combining cellulose nanocrystals (CNCs) with a polydiolcitrate elastomer exhibiting shape memory properties. In this composite, CNCs provide an intense structural coloration and improve the overall mechanical cohesion, while the elastomer drastically reduces the intrinsic brittleness of the photonic cellulose film and enables the shape memory effect. The fabricated samples are characterized by polarized optical microscopy, scanning electron microscopy and thermomechanical programming. The obtained results demonstrate that this hybrid material retains its chiral nematic structure and performs shape recovery in thermomechanical experiments thus widening the functionality of the independent components. Keywords cellulose nanocrystals; cholesteric; polydiolcitrates; shape memory; biomimetic Plastics are key materials in many aspects of daily life, ranging from packaging, to construction, to medical applications. The replacement of conventional plastics with biocompatible and biodegradable ones enables to exploit the versatility of polymeric materials with the advantage of using sustainable fabrication approaches. Within this context, photonic materials produced by self-assembly of biopolymers are receiving growing interest in the materials community.1-3 Many photonic structures with diverse optical responses have been produced using a large variety of biomaterials and fabrication methods. *Corresponding Authors: C.L.: c.lopez@csic.es; S.V.: sv319@cam.ac.uk. 1 Institut de Ciència de Materials de Barcelona, Consejo Superior de Investigaciones Científicas, Carrer dels Til·lers S/N, Campus de la UAB, 08193 Bellaterra, Barcelona, Spain. Author ContributionsThe manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Europe PMC Funders Group Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts 4-6 However, there are limitations on the different functionalities that can be achieved using only sustainable and biocompatible polymers. As an example, cellulose-based photonic structures can provide strong, intense colorations but they are generally very brittle.7 The addition of organic and inorganic matrices to such cellulose structures improves their mechanical properties but either comports the loss of the photonic effect or reduces the fully biocompatibility of the final composite.8Here we present a hybrid cellulose-based photonic structure exhibiting shape memory, fabricated by combining cellulose nanocrystals (CNCs) photonic films with a polydiolcitrate elastomer.9 In particular, we directly impregnate and embed colored CNC films with hydroxyl-dominant poly(dodecanediol-co-citrate) (PDDC-HD).10 The CNCs contribute both to the structural coloration of the film and to its overall mechanical cohesion, while the PDDC-HD provides both flexibil...

Controlling the Photonic Properties of Cholesteric Cellulose Nanocrystal Films with Magnets

“…[1] Cellulose nanocrystals (CNCs) are an excellent example of such a biosourced nanomaterial, owing to a unique combination of chemical, mechanical, and optical properties, [2,3] which explains the increase of interest in this system for applications as pigments, [4] security coatings, [5,6] sensing or responsive materials, [7][8][9][10][11][12] and mesoporous chiral nanotemplates. Such approaches can offer a cost-effective and scalable solution to design materials with a desired optical response.…”

“…Such approaches can offer a cost-effective and scalable solution to design materials with a desired optical response. [1] Cellulose nanocrystals (CNCs) are an excellent example of such a biosourced nanomaterial, owing to a unique combination of chemical, mechanical, and optical properties, [2,3] which explains the increase of interest in this system for applications as pigments, [4] security coatings, [5,6] sensing or responsive materials, [7][8][9][10][11][12] and mesoporous chiral nanotemplates. [13][14][15] Colloidal suspensions of CNCs exhibit a cholesteric liquid crystalline behavior above a threshold concentration [16][17][18][19][20] that can be retained upon solvent evaporation to form dry films that display a strong photonic response.…”

3D Printing of Magnetoresponsive Polymeric Materials with Tunable Mechanical and Magnetic Properties by Digital Light Processing

“…4D printing aims at exploiting advanced materials responding to external stimuli to program the actions of the printed objects . Several stimuli‐responsive materials—e.g., electroactive polymers, hydrogels, and nanocomposites—have been investigated for a broad variety of applications, from micro‐ and soft‐robotics to biomedicine . Among the different strategies, an accessible pathway to fabricate stimuli‐responsive (4D) printed objects consists in magnetizing a soft‐polymer by loading the polymeric matrix with magnetic fillers, such as particles of magnetite (Fe 3 O 4 ) or neodymium–iron–boron (NdFeB) .…”

Iridescent Chiral Nematic Mesoporous Organosilicas with Alkylene Spacers

“…[32] The CNCs arrange into a Bouligand structure, where the crystallites themselves are aligned in layers, but twist with a characteristic helical pitch, P. It is the repeating helicoidal structure that leads to diffraction of circularly polarized light from the CNC films. [30,[34][35][36][37][38][39][40][41][42][43][44][45][46][47] In 2010, we discovered that films of mesoporous silica with chiral nematic structure could be prepared using CNCs as a template. [30,[34][35][36][37][38][39][40][41][42][43][44][45][46][47] In 2010, we discovered that films of mesoporous silica with chiral nematic structure could be prepared using CNCs as a template.…”

“…[33] Many researchers are making new materials that take advantage of the unique properties of CNCs. [30,[34][35][36][37][38][39][40][41][42][43][44][45][46][47] In 2010, we discovered that films of mesoporous silica with chiral nematic structure could be prepared using CNCs as a template. [20] When Si(OR) 4 is condensed with CNCs in water, the resulting composite film contains silica and a chiral nematic assembly of CNCs.…”