3D Printing of Transparent Silicone Elastomers

Abstract

In this paper, inks for transparent elastomers that are formulated by matching the refractive index of silica and polysiloxanes are described. The transparent inks transmit up to ≈90% of 700 nm light through 1 cm and remain transparent when solidified. The inks and solidified materials exhibit a thermochromic effect. This thermochromic effect can be controlled by the refractive index mismatch. Transparency may increase or decrease as temperature increases, depending on the refractive index mismatch of the base polysiloxane and silica. It is found that the rheological properties of the ink depend on the distribution of silica particles, which is dictated by silica functionality, weight content, and processing. Siloxane precursors that vary in chemical functionality are introduced to tailor the mechanical properties of the printed elastomers, which obtain stretchability >65% along with a tensile modulus of 1.9 MPa. After optimizing siloxane chemistry and ink processing, the authors are able to print transparent elastomers. Potential applications are demonstrated for printed structures by printing encapsulation structures for light‐emitting diodes, semitransparent dye‐filled structures, a microfluidic mixing device, and a multimaterial structure that exhibits temperature‐dependent camouflage.

3D Printing of Double Network Granular Elastomers with Locally Varying Mechanical Properties

“…These shortcomings limit the range of mechanical properties a given elastomer formulation can attain, as summarized in Figure 8a. [2,35,[46][47][48][49][50][51][52][53][54] By contrast, the stiffness and ultimate tensile strain of our DNGE can be over a wide range by independently adjusting the composition of the microparticles and the 2 nd elastomer network. Indeed, the range of Young's moduli and ultimate tensile strains our 3D printable material can attain exceeds that of any previously published 3D printable elastomer system, as summarized in the Ashby plot in Figure 8a.…”

“…[13,14,23,24] The rheological properties of these inks have been adjusted, for example, by adding rheomodifiers such as nanoparticles. [39,45] These rheomodifiers render the recycling of elastomers challenging and often lead to safety [2,35,47,50,51,53] and have not been (empty diamonds) [46,48,49,52,54] modified with nanoparticles (NPs). The DNGE system introduced here (green shaded area) can span an unprecedented range of stiffnesses and ultimate tensile strains.…”

“…DNGEs with different mechanical properties. a) Ashby plot of bulk elastomers that have been 3D printed through DIW from precursor solutions that have (filled diamonds)[2,35,47,50,51,53] and have not been (empty diamonds)[46,48,49,52,54] modified with nanoparticles (NPs). The DNGE system introduced here (green shaded area) can span an unprecedented range of stiffnesses and ultimate tensile strains.…”

3D printable and stretchable PVA‐PAAm dual network hydrogel with conductivities for wearable sensors

“…Many researchers add fumed silica to silicon elastic ink, which gives it superior rheology and printability. 34,36 In this paper, fumed silica was used as the rheological modifier of DIW ink. To investigate the rheological tailoring effect of fumed silica, 6, 10, and 14 wt% fumed silica was added to PVA/PAAm/CaCl 2 solution.…”

All-Silicone 3D Printing Technology: Toward Highly Elastic Dielectric Elastomers and Complex Structures

“…The 3D printing of silicones has drawn a lot of interest from the scientific and industrial communities and has the potential to solve societal challenges (healthcare, human/machine interfaces, personalized medicine, etc. ). − …”