Decoupling of Mechanical and Transport Properties in Organogels via Solvent Variation

Abstract

Organogels have recently been considered as materials for transdermal drug delivery media, wherein their transport and mechanical properties are among the most important considerations. Transport through organogels has only recently been investigated and findings highlight an inextricable link between gels’ transport and mechanical properties based upon the formulated polymer concentration. Here, organogels composed of styrenic triblock copolymer and different aliphatic mineral oils, each with a unique dynamic viscosity, are characterized in terms of their quasi-static uniaxial mechanical behavior and the internal diffusion of two unique solute penetrants. Mechanical testing results indicate that variation of mineral oil viscosity does not affect gel mechanical behavior. This likely stems from negligible changes in the interactions between mineral oils and the block copolymer, which leads to consistent crosslinked network structure and chain entanglement (at a fixed polymer concentration). Conversely, results from diffusion experiments highlight that two penetrants—oleic acid (OA) and aggregated aerosol-OT (AOT)—diffuse through gels at a rate inversely proportional to mineral oil viscosity. The inverse dependence is theoretically supported by the hydrodynamic model of solute diffusion through gels. Collectively, our results show that organogel solvent variation can be used as a design parameter to tailor solute transport through gels while maintaining fixed mechanical properties.

Thermosensitive Hydrogels of BAB Triblock Copolymers Exhibiting Gradually Slower Exchange Dynamics and an Unexpected Critical Reorganization Temperature Upon Heating

“…Gels are solid-like materials consisting of two or more components, the main constituent being a liquid which can be water (hydrogels), an organic solvent (organogels − ), an ionic liquid (ionogels − ), or in some cases both water and an organic solvent (organohydrogels). They can find applications in various fields including the food industry, − the health sector, − coatings and sealants, energy , storage, enhanced oil recovery, organic electronics, or catalysis and sustainable chemistry, for example.…”

Fundamental Principles and Emerging Opportunities for Selectively‐Solvated Block Copolymer Networks in Nonpolar Media: A Perspective

“…Since diffusive transport and mechanical properties are intimately connected to the TPEG network and copolymer nanostructure and since these features are tied directly to the properties of the incorporated oil, the mechanical and transport properties of TPEGs must be decoupled for drug delivery purposes. An important step in this direction has been achieved [ 136 ] by systematically varying the viscosity of the midblock‐selective oil.…”

Tunable thermoplastic elastomer gels derived from controlled-distribution triblock copolymers with crystallizable endblocks

“…For example, styrenic TPEGs constitute excellent anthropomorphic surrogates with electromechanical properties comparable to mammalian skeletal muscle, 14 and they are likewise suitable for transdermal drug delivery. 41 Crystallizable TPEGs are anticipated to improve these uses through enhanced stability. Moreover, these materials provide a rare opportunity to visualize the midblock of triblock copolymer systems and, by doing so, explore the direct relation between midblock conformations and their desirable mechanical properties.…”