Additive manufacturing of silicone structures: A review and prospective

Liravi, Farzad; Toyserkani, Ehsan

doi:10.1016/j.addma.2018.10.002

Cited by 76 publications

(80 citation statements)

References 75 publications

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“…Polydimethylsiloxane (PDMS)‐based elastomers are found in a host of applications, from adhesives and biomaterials to soft robotics and three‐dimensional printing . These elastomers are also common in fundamental research on soft matter physics and mechanics.…”

Section: Introductionmentioning

confidence: 99%

Extracting uncrosslinked material from low modulus sylgard 184 and the effect on mechanical properties

Glover

McLaughlin

McFarland

et al. 2020

Journal of Polymer Science

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Commercial silicone elastomers are commonly used in soft materials research due to their easily tunable mechanical properties.However, conventional polydimethylsiloxane (PDMS) elastomers with moduli below $100 kPa contain uncrosslinked free molecules, which play a significant role in their behavior. To utilize these materials, it is important to quantify what role these free molecules play in the mechanical response before and after their removal. We present a simple and inexpensive extraction method that enables the removal of free molecules from a lightly crosslinked sheet of Sylgard 184, a commercially available PDMS elastomer. The materials can contain a majority of free molecules yet maintain a thin and flat geometry without fractures after extraction. Subsequently, we compare the modulus, maximum stretchability, and hysteresis behavior with mixing ratios ranging from 60:1 to 30:1, before and after extraction. We show that the modulus, maximum stretchability, and dissipation increase upon extraction. Moreover, our approach offers a route to prepare crosslinked silicone elastomers with a modulus as low as $20 kPa without free molecules from a commercially available kit.

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Section: Introductionmentioning

confidence: 99%

Extracting uncrosslinked material from low modulus sylgard 184 and the effect on mechanical properties

Glover

McLaughlin

McFarland

et al. 2020

Journal of Polymer Science

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“…[106] 3D material extrusion is also the basis for several direct 3D printing of silicone approaches. [107] Selective laser sintering (SLS) fabricates objects by depositing a thin layer of polymer powder across the build plate and then selectively fusing the polymer in the layer to produce the desired solid pattern. [108] The build plate is then lowered, a recoater deposits a new layer of powder over the previous layer and the whole process repeats.…”

Section: From Hand-crafting To Advanced Manufacturingmentioning

confidence: 99%

“…[18] For example, the most common prosthetic material, silicone, is often cast in 3D printed molds for clinical use. [5,120] Research is also underway for direct 3D printing silicone via extrusion, [107,121] photocuring, [4,122] or material jetting methods, [15,123] although many challenges still remain. [124] A modern soft-tissue prosthetic comprises a skin-like layer which is typically bonded to a substructure to maintain shape and, in some cases, include magnetic or mechanical attachment clips [125] (see Figure 2b).…”

Section: Polymers In Prostheticsmentioning

confidence: 99%

“…Direct approaches, on the other hand, involves the layer-by-layer extrusion, jetting, or polymerization of silicone. [107] Although desirable for ease-of-fabrication, the use of direct 3D silicone printing in prosthetics is limited due to visible layering from the progressive polymerization, potentially rendering the printed prosthetic visually unappealing. [4,15,17,107] One extrusion approach utilizes a two-part RTV silicone tailored to achieve optimal mechanical characteristics.…”

Section: Silicone For 3d Printingmentioning

confidence: 99%

“…[107] Although desirable for ease-of-fabrication, the use of direct 3D silicone printing in prosthetics is limited due to visible layering from the progressive polymerization, potentially rendering the printed prosthetic visually unappealing. [4,15,17,107] One extrusion approach utilizes a two-part RTV silicone tailored to achieve optimal mechanical characteristics. [18] In this method, the two components are separately loaded into syringe pumps and extrude the components into a mixing extruder prior to deposition onto the build plate.…”

Section: Silicone For 3d Printingmentioning

confidence: 99%

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Past, Present, and Future of Soft‐Tissue Prosthetics: Advanced Polymers and Advanced Manufacturing

et al. 2020

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past 30 years, [12,13] it is only the last decade that has seen its rapid development as part of the fourth industrial revolution. [14] This change in practice is evidenced by the significant fraction of recent literature describing advances in 3D printed prostheses, including technological advances [4,15-18] and clinical reports. [19,20] Further innovations involving collaborations between clinicians, academics, and industry, promise even greater capabilities. The future will see 3D printers that can mix materials as desired during fabrication [21] and those that can 3D print organic semiconductors and piezoelectric polymers for sensing and bionics [22-24] (Figure 1). This report is focused on polymers for soft tissue, external, personalized, prosthetics with clinical applications for the ear, [25] nose, [26] eye, [27] face, [28] breast, [29] and hand. [30] The characteristics of both traditional and 3D printable polymeric materials, as well as current advanced manufacturing technologies and those in development, are also reviewed. The earliest evidence of prosthetics dates back to ≈2300 BC, where Egyptian mummies have been discovered with eye, nose, and genital reconstructions fashioned from plaster packed with mud, sand, linen, butter, or soda (Figure 1). [31] Wood, cloth, natural waxes, resins, and metals were later used as the material of choice for rudimentary prostheses. [32] Prostheses remained relatively unchanged for thousands of years until the 16th century, where prosthetic noses and eyes were made from parchment, wax, wood, hard rubber, gold, silver, and copper. [33] Metals continued as a fundamental material throughout the 19th century, largely due to their ability to be shaped and molded as needed. [34,35] One of the first polymers to be used in prosthetics, poly(methyl methacrylate) (PMMA), was developed in response to the glass shortages in the World Wars of the 20th Century. [36] This polymer went on to become the most common prosthetic material of the time, and still finds use today in artificial eyes [33] and prosthetic substructures. [37] Further innovations in the 20th century produced many new polymers, such as vinyls, copolymers, plastisols, and one of the most significant materials in prosthetics, silicone. [38] Discovered in the early 1900s by Fredrick Kipping, silicone was first used in prosthetics by George W Barnhart in 1960. [39] This versatile polymer remains a primary prosthetic material today due to its soft tissue-like properties, ease of manipulation, chemical inertness, durability, and excellent biocompatibility. [40,41] The search for alternative materials Millions of people worldwide experience disfigurement due to cancers, congenital defects, or trauma, leading to significant psychological, social, and economic disadvantage. Prosthetics aim to reduce their suffering by restoring aesthetics and function using synthetic materials that mimic the characteristics of native tissue. In the 1900s, natural materials used for thousands of years in prosthetics were replaced by syntheti...

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An Emulsion Approach to Resolve the Paradox of 3D Printing of Very Soft Silicones

Perrinet

Courtial

Colly

et al. 2020

Adv Materials Technologies

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3D printing of silicone has been a challenge for medical applications for several years. The main property of medical silicone (mostly polydimethylsiloxane) is its mechanical similitude with human tissues. The very soft tissues as prostate, skin, liver, etc, are of Young's modulus lower than 100 kPa. 3D printing for such soft materials is not as obvious as printing thermoplastic polymers. In this work, the goal is to elaborate formulations of room‐temperature‐vulcanizing (RTV) silicone leading to final materials of Young's modulus down to 25 kPa while being processable by liquid deposition modeling, a layer by layer deposit of extruded filament. The main challenge is keeping the material with a sufficient firmness during the process to maintain the shape of the object but without increasing its final rigidity. Therefore, a RTV silicone is mixed with a hydrophilic liquid to create an emulsion of high yield stress behavior. Different emulsions are tested to optimize the composition on the basis of rheological measurements carried out to determine the yield stress variation and compare it to an emulsion model. Then, after printing and curing, the hydrophilic liquid is removed to create a material of fine porosity and consequently of low Young's modulus.

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Additive manufacturing of silicone structures: A review and prospective

Cited by 76 publications

References 75 publications

Extracting uncrosslinked material from low modulus sylgard 184 and the effect on mechanical properties

Extracting uncrosslinked material from low modulus sylgard 184 and the effect on mechanical properties

Past, Present, and Future of Soft‐Tissue Prosthetics: Advanced Polymers and Advanced Manufacturing

An Emulsion Approach to Resolve the Paradox of 3D Printing of Very Soft Silicones

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