Issue 15, 2021

Amphiphilic, thixotropic additives for extrusion-based 3D printing of silica-reinforced silicone

Abstract

The ability to utilize extrusion-based, direct ink write (DIW) 3D printing to create silica-reinforced silicones with complex structures could expand their utility in industrial and biomedical applications. Sylgard 184, a common Pt-cure silicone, lacks the thixotropic behavior necessary for effective printing and its hydrophobicity renders cured structures susceptible to biofouling. Herein, we evaluated the efficacy of various PEO-silane amphiphiles (PEO-SAs) as thixotropic and surface modifying additives in Sylgard 184. Eight amphiphilic PEO-SAs of varying architecture (e.g. linear, star, and graft), crosslinkability, and PEO content were evaluated. Modified formulations were also prepared with additional amounts of silica filler, both hexamethyldisilazane (HMDS)-treated and dimethyldichlorosilane (DiMeDi)-treated types. Numerous PEO-SA modified silicone formulations demonstrated effective water-driven surface hydrophilicity that was generally diminished with the addition of HMDS-treated silica filler. While increased yield stress was observed for PEO-SA modified silicones with added HMDS-treated filler, none achieved the initial target for 3D printing (>1000 Pa). Only the formulations containing the DiMeDi-treated filler (17.3 wt%) were able to surpass this value. These formulations were then tested for their thixotropic properties and all surpassed the targets for recovered storage modulus (G′) (>1000 Pa) and loss factor (<0.8). In particular, the triblock linear PEO-SA produced exceptionally high recovered G′, low loss factor, and substantial water-driven restructuring to form a hydrophilic surface. Combined, these results demonstrate the potential of silicones modified with PEO-SA surface-modifying additives (SMAs) for extrusion-based, DIW 3D printing applications.

Graphical abstract: Amphiphilic, thixotropic additives for extrusion-based 3D printing of silica-reinforced silicone

Supplementary files

Article information

Article type
Paper
Submitted
24 Feb 2021
Accepted
07 Mar 2021
First published
15 Mar 2021

Soft Matter, 2021,17, 4133-4142

Amphiphilic, thixotropic additives for extrusion-based 3D printing of silica-reinforced silicone

J. Suriboot, A. C. Marmo, B. K. D. Ngo, A. Nigam, D. Ortiz-Acosta, B. L. Tai and M. A. Grunlan, Soft Matter, 2021, 17, 4133 DOI: 10.1039/D1SM00288K

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