3D printable tough silicone double networks

Abstract

Additive manufacturing permits innovative soft device architectures with micron resolution. The processing requirements, however, restrict the available materials, and joining chemically dissimilar components remains a challenge. Here we report silicone double networks (SilDNs) that participate in orthogonal crosslinking mechanisms—photocurable thiol-ene reactions and condensation reactions—to exercise independent control over both the shape forming process (3D printing) and final mechanical properties. SilDNs simultaneously possess low elastic modulus ( E 100% < 700kPa) as well as large ultimate strains (d L/L 0 up to ~ 400 %), toughnesses ( U ~ 1.4 MJ·m −3 ), and strengths ( σ ~ 1 MPa). Importantly, the latent condensation reaction permits cohesive bonding of printed objects to dissimilar substrates with modulus gradients that span more than seven orders of magnitude. We demonstrate soft devices relevant to a broad range of disciplines: models that simulate the geometries and mechanical properties of soft tissue systems and multimaterial assemblies for next generation wearable devices and robotics.

Soft, tough, and fast polyacrylate dielectric elastomer for non-magnetic motor

“…d Comparison of ultimate strength to modulus among VHB TM 4910, BA-S, BA-M, BA-L, BAC2, dielectric gel 37 , multiblock copolymers 33 , azo-grafted silicone 28 , nitroaniline modified silicone 18 , polyurethane 19 , alkyl thiols grafted silicone 16 and commercial Elastosil@Film 16 . e , Toughness plotted against Young’s modulus for VHB TM 4910, BA-S, BA-M, BA-L, BAC2, dielectric gel 37 , silicones with ionic liquids 17 , acrylic copolymer 25 , nitroaniline modified silicone 18 , nitrile modified silicone 39 , alkyl thiols grafted silicone 16 , 3D printable silicone 40 , and commercial Elastosil@Film 16 ( Supplementary Discussion ). …”

3D Printing of High Viscosity Reinforced Silicone Elastomers

“…The silicone formulations in this study were developed using vinyl terminated-polydimethylsiloxane (VTS) and polymercaptosiloxane- co -dimethylsiloxane (MFS) monomers as crosslinkers, see Scheme 1 . UV-initiated thiol-ene crosslinking of silicones was first described in the 1970s [ 42 ] and has since seen renewed interest for 3D printing [ 17 , 18 , 19 , 20 , 21 , 22 , 26 ]. A wide variety of VTS monomers are commercially available, and although the selection of mercapto-containing siloxanes is more limited, several synthetic approaches for their preparation have been described in recent years [ 23 , 43 ].…”

“…Moreover, in comparison to DIW technologies, SLA enables the design and build of more complex structures, including architectures with unsupported overhangs. Recently, several groups have reported on the SLA of silicones [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ] and/or related polysiloxane-containing materials [ 2 ], using predominately acrylate [ 23 , 24 , 25 , 27 ] and/or thiol-ene [ 17 , 18 , 19 , 20 , 21 , 22 , 26 ] crosslinking as workhorse chemistries. Notably, however, many reported SLA silicone formulations have lacked the addition of reinforcing filler.…”

“…Notably, however, many reported SLA silicone formulations have lacked the addition of reinforcing filler. Presumably, this is because the addition of filler sharply increases the viscosity of silicone formulations, which challenges the development of traditional SLA-based processing [ 18 ].…”

Efficient 3D printing via photooxidation of ketocoumarin based photopolymerization

“…Among various 3D printing techniques, photopolymerization-based digital light processing (DLP) has attracted particular attention [1][2][3][4]9,10,[12][13][14][15][16] , due to that the photopolymerization kinetics can be precisely controlled spatially and temporally [19][20][21][22][23][24][25][26][27][28] . In this manner, 3D printing can be well controlled with rationally designed monomers 7,[29][30][31] , photoinitiating systems [32][33][34] , chain transfer agents 35 , oxygen inhibition layers 2 , mobile liquid interfaces 1 , and hardwares 6,17,36 . However, the light transmitted through the solidified polymer layers is highly likely to trigger undesired lateral photopolymerization during the printing of subsequent layers and therefore leads to deteriorated print resolution 1,9 .…”