Governmental organisations use a diversity of policy instruments for sustainability goals. In the field of materials, they aim to advance the reuse of materials on the one hand. On the other hand, they also want to control critical raw materials (CRMs) to protect society against scarcity. Information sharing is required to monitor for both objectives. Research into information sharing for the circular economy mainly focuses on using ICT to follow entire products, such as digital product passports. However, research into information sharing for reuse flows and monitoring at the level of materials is limited so far. Therefore, in this paper, we derive the following requirements for information sharing to support the monitoring of materials and CRMs in particular: 1) businesses and government organisations should have access to the complete history of materials; 2) businesses should be able to share information on materials between different supply chains and industries; 3) information on materials should be reliable and tamper-resistant; 4) governments should be able to obtain a complete overview of the pool of CRMs in circulation and of who is responsible for them; 5) the system supporting the information sharing on materials should be highly robust and should not have a single locus of control. Based on this overview of requirements, we present a research agenda in which we identify challenges and related future research questions. @en