Certain embodiments of the invention include forming a material in situ by introducing into a space within a patient a water soluble polymer precursor of at least about 10,000 molecular weight solubilized in a flowable aqueous solution. Functional groups on the polymer precursor undergo covalent bonding in situ to form a solid and nonbiodegradable material having a swellability less than about 20% v/v and a Young's modulus of at least about 100 kPa within about 30 seconds to about 30 minutes of initiating a chemical reaction of the functional groups to form the solid material.
