Hybrid Polymer Hydrogels with Regions of Distinct Properties
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This thesis investigates a new approach to create hybrid polymer hydrogels that comprise multiple gel types juxtaposed in predetermined zones, with the unique properties of each gel being retained. The key is to ensure that the viscosities of pre-gel mixtures are sufficiently high when brought into contact and subsequently polymerized, preventing convective mixing at gel/gel interfaces. The final gel appears as a single, homogeneous material with robust interfaces between the dissimilar zones. By modifying the pre-gel viscosity, we construct hybrid hydrogels by a procedure that is quick, simple, and has fewer limitations than alternate methods. By varying the components of each gel, we have produced a vast array of hybrid hydrogels with regions of distinct chemical, optical, and mechanical properties. This has enabled the creation of strong, highly-extensible soft materials (e.g. a spinal disc mimic), and of gels bearing hidden patterns that can be revealed with a variety of stimuli.