PDRCs can also come in the form of metafabrics, which can be worn as clothing to shield and regulate body temperatures in times of extreme heat. Most metafabrics are made of petrol-based fibers, although research and development of sustainable or regenerative materials is ongoing. For instance, Zhong et al. states that "new flexible cellulose fibrous films with wood-like hierarchical microstructures need to be developed for wearable PDRC applications."