(255bd) Preparation and Timed Release Properties of Self-Rupturing Gels

Polyelectrolytes attract widespread interest as building blocks for stimulus-responsive soft materials that can form, dissolve or change their properties on demand. Here, we exploit this stimulus sensitivity to prepare self-rupturing gels, which can serve as self-destructing soft devices. These gels are synthesized from an inexpensive commercial polyelectrolyte, poly(acrylic acid) (PAA), and have highly non-uniform crosslink densities. The disparate crosslink densities give rise to non-uniform osmotic swelling, which not only changes the gel shape, but also generates stresses that are high enough to induce gel rupture. The time required for this rupture depends on the variability in the crosslink densities, and the size and arrangement of the variably-crosslinked gel sections. Further, we show how these self-rupturing gels can be utilized in delayed/timed release applications by preparing self-rupturing hydrogels with capsule-like â??container and lidâ? structures. The self-rupture of these containers removes the lid and releases the entire payload after a pre-programmed delay (which is on the order of days and can be tuned by varying the rupture time).