As the production volume of polymers increases, so does the amount of plastic waste. Plastic recycling is one of the concepts to address in this issue. Unfortunately, only a small fraction of plastic waste is recycled. Even with the development of polymers for closed loop recycling that can be in theory reprocessed infinitely the inherent dilemma is that because of collection, cleaning and separation processes the obtained materials simply are not cost competitive with virgin materials. Chemical upcycling, the conversion of polymers to higher valuable products, either polymeric or monomeric, could mitigate this issue. In the following article, we highlight recent examples in this young but fast-growing field. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)'.