Abstract: Compositions and methods for forming composites of polymer fibers, yarns, and textiles having enhanced elastocaloric and twistocaloric performance are provided herein. The composites can permit reversible temperature shifts within the materials, and can be used, for example, in energy conversion and thermal storage systems. These composites can be formulated by melt spinning the polymer fibers and using combinations of twisting and stretching of the polymer fibers. The fibers can include, for example, a base polymer that can be amorphous, or substantially amorphous, and desired alignment can occur, for example, by performing one or more of the various provided for techniques. In at least some embodiments, the composite materials can be further enhanced by including one or more phase change materials (PCMs), such as by cross-linking the one or more PCMs with one or more polymers and/or directly attaching the PCM(s) to the polymer(s).