Phototunable Thermoplastic Elastomer Hydrogel Networks
At A Glance
An elastomeric hydrogel system which can be mechanically tuned both before and after incorporation of water by exposure to UV irradiation.
Hydro gel networks are of broad scientific interest due to their utility and compatibility in a variety of applications including tissue scaffolds, encapsulation matrices, delivery agents, and separation membranes. Numerous methods to produce hydrogel networks have been reported, generally exploiting physical or chemical cross-linking of hydrophilic polymers and monomers in solution. However, conventional systems like these based on spatially random or statistical crosslinking mechanisms can suffer from weakly-defined network structures with a large distribution of mesh sizes arising from the random nature of the cross-linking process. Heterogeneity in structure and mesh size across the sample profile can result in spatial inconsistencies in mechanical properties, swelling, and mass transport within the hydrogel. As such, there is a long-felt, but unmet need for hydrogel systems that do not exhibit heterogeneity in the structure and mesh size within the hydrogel.
Researchers at Colorado State University have developed a patented method for fabricating elastomeric, mechanically tunable hydrogels using a one component system of a sphere-forming amphiphilic block copolymer. The resultant solid is swollen in aqueous media to produce hydrogels exhibiting excellent mechanical properties and fatigue resistance.
The mechanically adjustable polymer material is produced by using melt-state self-assembly of poly(A)-block-poly(B) or AB diblock copolymers which are designed to thermodynamically prefer a sphere morphology during microphase separation of the covalently linked blocks. Each spherical aggregate contains a preferred number of block copolymer chains, depending on the overall molecular weight of the block copolymer and its composition (usually given as a mass fraction of each block in the block copolymer). These AB diblock copolymers are modified with a light sensitive functionality (anthracene, PS-PEO-An) which allows for installation of ABA triblock copolymer tethers between PS cores either before or after the addition of water. Incorporation of tethers by UV exposure before swelling results in a readily swellable network to produce a hydrogel solid. Addition of water before incorporation of tethers results in a malleable liquid-like material which can be molded or poured and then exposed to UV light to install the network tethers.
- Long-term mechanical stability
- Hydrogel can be cured to fit any desired shape
- Exceptional fatigue resistance
- Elastic recovery is ideal for mechanically-demanding applications
- Direct integration of thermally sensitive components – such as pharmaceuticals, enzymes, antibodies, cells, etc.
- Soft Tissue replacement and repair (such as Knee meniscus and intervertebral disc)
- Wound dressing/wound healing materials
- Intra- and extra-ocular lens / lens modification materials
- Hydrated adhesives
- Coating materials for biomedical devices – catheters, stints, etc.
- Elastic separation membranes for a range of molecules (light gases to protein assemblies and biologics)
- Mechanical energy adsorbers (such as footwear, sportswear padding, helmets, and protective gear)
- Substrates for localized and integrated drug delivery
Huq, Nabila A., et al. “Phototunable Thermoplastic Elastomer Hydrogel Networks.” Macromolecules, American Chemical Society, 2017, pubs.acs.org/doi/10.1021/acs.macromol.6b02005.
Huq, Nabila A. “Phototunable Block Copolymer Hydrogels” (Doctoral dissertation). Mountain Scholar, 2017, Colorado State University, Library. mountainscholar.org/bitstream/handle/10217/185744/Huq_colostate_0053A_14567.pdf?sequence=1&isAllowed=n.
Last updated: April 2020