Materials scientists often focus on the creation of new materials with a specific purpose in mind. The purpose could be a simple load-bearing application or something more ‘functional’ like imparting antimicrobial resistance. In Green Materials, the purpose is often sustainability, which can take on a host of definitions. Sustainability could mean the use of more renewable resources or less energy-intensive processes to produce a high-quality material. The question then becomes how to measure the ‘sustainability’? Did the use of renewable resources really result in a more sustainable product or did increased processing steps negate the sustainability gain? Conversely, did a reduction in processing steps result in a true sustainability gain if the renewable resource is not easy to obtain? These are interesting questions and Volume 14, Issue 3 of Green Materials delves into some of these important aspects of green engineering and sustainability.
The construction industry is very natural resource-intensive and a prime target for sustainability practices. Manan et al.1 provide an extensive review on the use of recycled materials in concrete and quantify the carbon dioxide and cost reductions through the use of those recycled materials. Processing improvements can be key to sustainability improvements, as shown by Guan et al.2 and Gupta et al.3 Aluminum materials can be used to produce hydrogen through a simple reaction. Guan et al.2 show that improvements in the ball milling process to produce aluminum composites can greatly affect the hydrogen yield when subsequently converted. Gupta et al.3 show how simple changes in raster angle during three-dimensional printing of polylactic acid (PLA) can improve the polymer properties. PLA is a commodity biobased and biodegradable polymer produced from the fermentation of sugar to lactic acid. Viscose fibers are produced from cellulose, and Mostafa et al.4 show that they can be coated with zinc oxide nanoparticles and β-cyclodextrin to improve fiber properties. While the cellulose and β-cyclodextrin could be considered renewable materials, the improvements in the fiber point to no obvious sustainability and processing gains. For instance, the fibers have higher ultraviolet resistance meaning that less sunscreen could be used. The fibers also exhibit less wrinkling so ironing is not needed.
Probably no field has had more of an impact on processing and materials production than the discovery of new catalysts. Catalyst discovery, whether synthetic metal-based catalysts for direct use in the materials industry or enzyme catalysts for biological reactions, has resulted in a very large number of Nobel Prizes and game-changing improvements in the field. Dewi and Khaligh5 show the development of amine-tethered ionic organocatalysts to convert carbon dioxide into cyclic carbonates. The reaction allows for the fixation of carbon in useful ‘green’ products. Finally, Zhou et al.6 describe the development of new photocatalysts that can be used to degrade methylene blue in water.
Volume 14, Issue 3 of Green Materials continues to show the variety of research happening in the field. Interestingly, Chang et al. offer a brief techno-economic analysis of their pomegranate material and Wang et al. offer time-temperature superposition data. Both studies do so with the intent of fostering engineering design and commercial adoption, highlighting the importance of thinking down the line when researching new materials.
