Mechanical Properties Tailoring of 3D Printed Photoresponsive Nanocellulose Composites

Abstract

3D printing technologies allow control over the alignment of building blocks in synthetic materials, but compositional changes often require complex multimaterial printing steps. Here, 3D printable materials showing locally tunable mechanical properties are produced in a single printing step of Direct Ink Writing. These new inks consist of a polymer matrix bearing biocompatible photoreactive cinnamate derivatives and up to 30 wt% of anisotropic cellulose nanocrystals. The printed materials are mechanically versatile and can undergo further crosslinking upon illumination. When illuminating the material and controlling the irradiation doses, the Young's moduli can be adjusted between 15 and 75 MPa. Moreover, spatially controlled illumination allows patterning stiff geometries, resulting in 3D printed structures with segments of different mechanical properties tailoring the mechanical behavior under compression. The high design freedom implemented by 3D printing and photopatternability opens the venue to rapid manufacturing of devices for applications such as prosthetics or soft robotics where the 3D shapes and mechanical properties must be tailored for personalized load cases.

Recent Progress in Active Mechanical Metamaterials and Construction Principles

“…[160] Similarly, photoreactive cinnamates had the property of reversible cycloaddition reaction when illuminated with wavelength >300 nm, which lead to a significant change in Young's modulus. Müller et al [161] took advantage of this to graft photoreactive cinnamates onto the surface of CNC (cellulose nanocrystals) and easily prepared some kinds of single-material honeycomb mechanical metamaterials by direct ink writing (DIW). When irradiated by light, Young's modulus of the specific area (marked in red) was increased because of the generation of a second polymer network, as shown in Figure 7a.…”

“…Owing to the advantages of remote control, accurate and quick response, light-responsive AMMs have many applications in the field of soft robotics, Zeng et al [157] utilized monolithic LCE film to design a microrobot by imitating the crawling movements of [161] Copyright 2020, Wiley-VCH. b) Origami metamaterials with different numbers of pop-up units and the schematic of unfolding effect under light stimulation.…”

“…Müller et al. [ 161 ] took advantage of this to graft photoreactive cinnamates onto the surface of CNC (cellulose nanocrystals) and easily prepared some kinds of single‐material honeycomb mechanical metamaterials by direct ink writing (DIW). When irradiated by light, Young's modulus of the specific area (marked in red) was increased because of the generation of a second polymer network, as shown in Figure 7 a .…”

“…Light-responsive active metamaterials. a) Comparison of compression results of light-response metamaterials with and without light source stimulation on the local region [161]. Copyright 2020, Wiley-VCH.…”

Interfacial jamming reinforced Pickering emulgel for arbitrary architected nanocomposite with connected nanomaterial matrix

“…Three-dimensional (3D) nanocomposite (NC) printing offers a programmable, facile, and flexible manner to translate the inherent physical properties of nanomaterials into 3D topologies and geometries, which are appreciated by various sectors, such as microelectronics 1 , aerospace 2 , engineered composites 3 , energy storage 4 , sensors 5 , 6 , and healthcare 7 – 11 . Conventionally, NCs gain 3D printability by incorporating nanomaterials into a printable matrix, such as hydrogels, polymer, and resin 9 , 12 . However, such type of NCs lacks tight control over the nanomaterial connection 13 , even though the connection can maximize nanomaterial advantages, such as electrical and thermal conductivity 14 , 15 .…”