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Anniversaries are always a cause for celebration, and a 100th birthday is definitely a very special event. Humans rarely reach this age and even for scientific societies there is no guarantee that their raison d’être will last that long. However, our Kolloid-Gesellschaft has survived these many years very well and has now reached such an age.

When it was founded in 1922, Colloid Science had already been around for a long time. In fact, mankind has used colloidal systems since the onset of civilisation, just for most of the time without having the proper scientific concepts to comprehend them. The term “colloid” was coined in 1861 by Thomas Graham, but despite numerous activities in the field of colloid research in the nineteenth century, it still remained a fledgling field of science and little organised into a separate discipline. In order to recognise the overarching common grounds of Colloid Science, it took not only many research activities, often conducted in the field of applied science, but also a growing understanding of the unifying fundamental concepts that underlie it, as well as more advanced experimental methods to develop the field conceptually further. This is precisely what happened in the beginning of the twentieth century, as recognised some years later by a series of Nobel Prizes that were awarded in quick succession in the field of Colloid Science. These went in 1925 in chemistry to Richard Zsigmondy for “his demonstration of the heterogeneous nature of colloid solutions and for the methods he used”, in 1926 in chemistry to Theodor Svedberg for “his work on disperse systems” and in physics to Jean Baptiste Perrin for “his work on the discontinuous structure of matter, and especially for his discovery of sedimentation equilibrium”, and in 1932 in chemistry to Irving Langmuir for “his discoveries and investigations in surface chemistry”.

With these significant advances occurring just about 100 years ago, a more unified picture of the field emerged and it became increasingly clear that Colloid Science plays a major role in many applications, and many of these, such as detergency, pharmaceutics, and cosmetics, were also developing enormously in the early twentieth century. This made many scientists and engineers realise that because of the unique features pertaining to Colloid Science a scientific organisation focussing on the topic of Colloid Science was needed in order to bring together all the people interested in this interdisciplinary subject. This then led to a call for the founding of such a society, which was published in 1922 in the Kolloid-Zeitschrift (the predecessor journal of Colloid and Polymer Science). The initiator was Wolfgang Ostwald, the son of Wilhelm Ostwald, Nobel laureate of 1909 for his work on kinetics and catalysis. Wolfgang Ostwald also became the first president of the Kolloid-Gesellschaft, which was officially founded during a scientific meeting in Leipzig on September 15, 1922.

Accordingly, Colloid Science was already a flourishing field a hundred years ago and it remained a very active field in the years that followed, continuously evolving further. The 1920s and 1930s saw the advent of electron microscopy, which made it possible to image objects below a size of 1 µm at high resolution, for instance making viruses visible for the first time. This was complemented by scattering techniques such as light scattering, X-ray scattering, and later on laser light scattering and neutron scattering, which made it possible to see structural features in reciprocal space, and thus gather complementary structural information. Fortunately, the arsenal of characterisation techniques has continued to evolve over the years, thereby giving colloid scientists all the tools they need to study the various colloidal systems in ever greater detail. Due to increasing synthetic advances and knowledge of how different components can be assembled into hybrid materials with increasing functionality, the resulting colloidal systems have become increasingly complex in structure and function, extending both to the lower size range and much bigger aggregates.

Accordingly, although Kolloid-Gesellschaft is already 100 years old, Colloid Science has remained a highly active and constantly evolving field. Thus, the Kolloid-Gesellschaft is 100 years old, but its scientific topics have remained young and fresh!

The 100 years of Kolloid-Gesellschaft were therefore a welcome occasion to have a really great anniversary celebration, and this took place at the 51st biennial Assembly of the Kolloid-Gesellschaft, entitled: “100 Years Colloid Society Colloid Science—as Modern as Ever” and was held at the Technische Universität Berlin from September 28 to 30, 2022. More than 200 participants were present at this meeting and not only from the German scientific community. The conference was a good example for the internationalisation of science across borders, as collaborations at both national and international levels have become more and more important to advance science and jointly address increasingly complex scientific questions. Accordingly, off the 200 participants, about 40% came from abroad, many of those from Europe but also from Japan, USA, Israel, Australia, India, and South Korea. This made the celebration of the birthday of a German scientific organisation a truly international event.

During the 3 days of this event, the entire field of Colloid Science was covered, with topics such as characterisation of complex structured colloidal systems, preparation of well-defined copolymers and functional nanoparticles, and investigations of microgels, always covering both experimental and theoretical advances. There were a total of 90 lectures and 91 poster presentations. Internationally highly renowned researchers, namely, Wiebke Drenckhan (Strasbourg, France), Junbai Li (Beijing, China), Michael Cates (Cambridge, UK), and Eric Furst (Delaware, USA) provided plenary lectures, and the plenary lecture by Joachim Venzmer (Essen, Germany) gave illuminating insights into the historical development of the Kolloid-Gesellschaft and how its topics have changed over time. Of course, the prizes of the Kolloid-Gesellschaft were also awarded during the conference. These prizes went to Helmut Coelfen (Liesegang Prize; Konstanz, Germany) for his work on analytical ultracentrifugation, Juliane Simmchen (Zsigmondy Stipend; Dresden, Germany) for her work on active colloids, Gero Decher (Steinkopff Prize; Strasbourg, France) for his work on the layer-by-layer technique, Paul Mulvaney (Ostwald Prize; Melbourne, Australia) for his work on optically active nanoparticles, and Peter Schurtenberger (Graham Prize; Lund, Sweden) for his contributions to international and interdisciplinary cooperation in the field of colloid research.

Ideally, of course, one would not only have the oral or poster contributions presented at a conference, but also a permanent version of it in printed form. Much of the work presented had already been published, but for some of the presented results this was not the case and they are now collected in this special issue of Colloid and Polymer Science. Our thanks go to the authors who helped to make this issue a success! We wish to share this special issue with the entire research community interested in developments in Colloid Science, and we hope that you will also enjoy reading about the various interesting research results that have been collected here.

In summary, this meeting was an extremely stimulating scientific event, much appreciated by the participants, where one could look back at how Colloid Science has developed, where it stands today, and one could also gain insights into its future development. It became possible in the form in which it was held by the generous support of the Deutsche Forschungsgemeinschaft (DFG), TU Berlin, Evonik Operations GmbH, and Springer—and, of course, by the marvellous work of many people involved in the organisation of the meeting.