Synthesis and characterization of porous polydimethylsiloxane structures with adjustable porosity and pore morphology using emulsion templating technique

Abstract

Porous polydimethylsiloxane (PDMS) framework with adjustable pore structures has been fabricated by polymerization of the continuous phase in the emulsion templates. Different types of surfactants, including nonionic (Triton X‐100), cationic (Benzalkonium chloride), anionic (sodium dodecyl sulfate), and silicone‐based block copolymer were used to stabilize the water‐in‐oil emulsion system. Deionized water with a wide range of internal phases varying from 10% to 60% by weight was employed to make the low internal phase emulsion and medium internal phase emulsion. The effect of surfactant type, surfactant concentration, and the internal phase volume on the stability of the emulsion, pore morphology, and pore size distribution was explored. The stability of the emulsion was investigated by comparing the pore morphology of the cured sample at different set times, such as 0, 6, and 72 h. Scanning electron microscopy was employed for the characterization of the porous structures. The image analysis was conducted, and the pore size distribution, porosity, and open‐cell ratio of each sample were calculated. Interconnected pores have been seen in the porous PDMS made from emulsions with an internal phase larger than 30%. The results demonstrated that the frequency of open‐cell pores and the pore size is dependent on the surfactant types.

Emulsion Gels as Precursors for Porous Silicones and All-Polymer Composites—A Proof of Concept Based on Siloxane Stabilizers

“…In the meantime, the polydispersity may be of interest for certain applications, as reported in the case of materials with gradient pore size for scaffolds and extracellular matrix [ 34 , 35 ]. Similar size and morphology of the pores and some adjustments in pore distribution by nature and concentration of the surfactants were reported by Abshirini et al [ 36 ], for porous silicones obtained by hydrosilylation in emulsion templating. Even larger pores were reported for porous silicones (sponges or foams) obtained with solid NaCl [ 37 ] or supercritical CO 2 [ 38 ] as templates.…”

Flexible capacitive pressure sensors with micro-patterned porous dielectric layer for wearable electronics

“…It indicated that the same mass of deionized water was separated into the micelles with different sizes, when the SDS concentration decreased from 1:20 to 1:80. It means that the internal pore size would increase as the SDS concentration decreased because of the larger micelles [34]. However, the pore size did not increase linearly when the SDS concentration decreased.…”

“…The outstanding characteristics of this sensor were mainly benefited from the specific protruding surface micro-structure and the internal pores, according to the previously mentioned. On the one hand, the distance of the two electrodes would decrease dramatically when the sensor suffered from an external force [21,33,34]. On the other hand, the air in the pores would be squeezed out, and the relative permittivity of the whole dielectric layer would increase simultaneously since the much smaller dielectric constant of air than PDMS [7,10,35].…”

Microzone Melting Method of Porous Reactor Fabrication with Structure-Controlled Microchannel Networks for High Yield In Situ DNA Synthesis

“…However, existing reports only focused on DNA synthesis on planar PDMS surfaces with low synthesis yield . Several fabricating methods of porous PDMS were reported, such as templating, − emulsion, − phase separation, , and 3D printing . As porous PDMS possesses a higher surface-to-volume ratio, it can provide a larger area for DNA synthesis and facilitate synthesis yield improvement.…”