Happy Birthday, Rolf Mülhaupt!

With this issue of Macromolecular Materials and Engineering, celebrating 25 years of the journal, the editors, friends, and colleagues congratulate Prof. Rolf Mülhaupt on the occasion of his 70th birthday in September 2024. The broad range of topics assembled in this volume reflects the impressive scope of topics, Rolf Mülhaupt's research has addressed. It was briefly sketched how these have evolved from the different stations of his career in a previous editorial in a sister journal.^[1]

The ten years that have passed since this review of Rolf Mülhaupt's outstanding and unconventional scientific career have certainly held unexpected developments. Only a few days after the conference “Makromolekulares Kolloquium” in Freiburg in February 2020 honored him on the occasion of his upcoming formal retirement from his chair position at the Institute of Macromolecular Chemistry, public and academic life were shut down by a pandemic. Also, he was not spared from “remote teaching” in the following. His scientific curiosity and productivity are, of course, uncompromised, as also evidenced by his published oeuvre. Within the breadth of Rolf Mülhaupt's contributions, as an example of his interests in the past decade, it is certainly appropriate to highlight additive manufacturing, reflected in a review article that has been cited already more than 2500 times since its appearance in 2017.^[2] This topic—in which he was active very early on actually—has moved on to—among others—3D printing of polyolefins with his team. This again takes advantage of his development of “all-polyethylene” composites, which achieve outstanding material performance yet are also well processable, thereby providing improved circularity. Concerning the intensely discussed issue of polymer materials' circularity, the scientific community continues to benefit from Rolf Mülhaupt's to-the-point and sometimes sobering assessments of reality, for instance in “Green Polymer Chemistry and Bio-based Plastics: Dreams and Reality”,^[3] a highly cited perspective on this research area and its future options.

Together with all other authors that have contributed to this volume, and with the entire team of the Macromolecular journals, I congratulate Rolf Mülhaupt on the occasion of his anniversary and wish him continued delight in science in the years to come!