Obituary Prof. Dr. Gerd Heppke

We mourn the loss of Professor Dr. Gerd Heppke, who passed away on 4 June 2022 at the age of 82. Gerd Heppke was a distinguished researcher and a brilliant teacher, who significantly influenced the progress of liquid crystal research. In this article, some of his achievements are reviewed in recognition of Gerd Heppke’s outstanding merits. Being a physicist by training, Gerd Heppke (Figure 1) received his Ph. D. in 1971 and his habilitation in 1975, became Professor at the Technical University of Berlin (TUB), founded a large research group in the division of physical chemistry, initiated and led an interdisciplinary research programme on liquid crystals at TUB, and established the special research area of ‘Anisotropic Fluids’ in Berlin. Heppke’s ability to guide interdisciplinary work in both physics and chemistry enabled the synthesis and characterisation of many new liquid crystalline compounds, in particular cholesteric liquid crystals and mesogenic chiral additives, ferroelectric smectic liquid crystals, low-molar-mass glass-forming liquid crystals, and bentcore mesogens. Through his extraordinary creativity, his continuous readiness to challenge state-of-the-art mainstream assumptions, his outstanding managing capabilities and hard work, Heppke facilitated the explanation of some surprising experimental observations and the discovery of new effects in the fields of re-entrant smectic phases, helix inversion of cholesteric phases, electric field effects in blue phases, ferroelectricity, antiferroelectricity and ferrielectricity of smectic C-phases, higher ordered smectic phases and phases of bent-core mesogens, optical storage effects, and optical nonlinearities (Table 1) [1–79]. In 1970, when Gerd Heppke started to get interested in liquid crystals [1], standard textbooks of physics and chemistry described the latter as being composed of rod-like molecules, which tend to align parallel to each other in certain temperature ranges, thereby forming mesophases, in particular a nematic (N) phase [in which the locally preferred direction of the molecules is uniform and can be described by the unit vector n, the director], a cholesteric (N*) phase [which appears in the presence of chiral molecules. i. e. molecules without mirror symmetry, and is characterised by a helical director field n(r)], or one of different smectic (Sm) phases [where the molecules form layers in addition to their orientational order]. Television and computer screens were heavy, bulky objects with large power consumption, based on cathode ray tubes (CRT), quite different from the flat liquid crystal displays (LCDs) that are ubiquitous, today. In the early 1970s, first wrist watch Figure 1. Prof. Gerd Heppke 1991 (Foto: Inge Kundel-Saro). LIQUID CRYSTALS TODAY 2022, VOL. 31, NO. 2, 18–27 https://doi.org/10.1080/1358314X.2022.2137989