Photopolymerization and its application in the dental, three‐dimensional (3D) printing, coating and electronic industry has become increasingly popular over the last decades. A huge variety of photoinitiators (PIs) and photoinitiating systems (PISs) have been developed that are able to generate reactive species, e. g. radicals, radical cations, and cations upon light absorption. In this Review, we focus on radical‐generating Type I PIs which undergo homolytic cleavage after irradiation with visible light. The possibility to utilize electromagnetic irradiation above 400 nm for the initiation of polymerization reactions provides several advantages such as a lower energy demand and higher curing depths in pigmented reactive systems. Recent developments of PIs based on phosphorus and group 14 elements as well as other selected concepts for Type I visible light initiators are outlined and discussed within this review.

This contribution deals with the synthesis and exploration of alkyne carbonate derivatives as biocompatible building blocks in the thiol–yne photopolymerisation reaction with the aim to facilitate the fabrication of tailor made medical devices by UV based additive manufacturing technologies. It turned out that the investigated alkyne carbonates offer curing rates similar to comparable acrylates, while providing much higher conversion and lower monomer cytotoxicity. Curing the synthesized building blocks in combination with the commercially available thiol pentaerythritol tetra(3-mercaptopropionate) (PETMP) leads to networks that degrade in aqueous alkaline and acidic media in a surface erosion manner. Additionally, a selective adjustment of the degradability is feasible by the choice and content of thiol monomers. Notably, monomers containing a tricyclo[5.2.1.0^2,6]decane-4,8-dimethanol backbone provide decent thermo-mechanical properties and appropriate impact strengths similar to polylactic acid (PLA). Most importantly, selected thiol–yne formulations were printed successfully with an accuracy of 40 × 40 μm, which seems to be sufficiently high to prints medical devices in appropriate resolution.

Natural and synthetic coumarin derivatives have gained increased attention in the design of functional polymers and polymer networks due to their unique optical, biological, and photochemical properties. This review provides a comprehensive overview over recent developments in macromolecular architecture and mainly covers examples from the literature published from 2004 to 2020. Along with a discussion on coumarin and its photochemical properties, we focus on polymers containing coumarin as a nonreactive moiety as well as polymer systems exploiting the dimerization and/or reversible nature of the [2πs + 2πs] cycloaddition reaction. Coumarin moieties undergo a reversible [2πs + 2πs] cycloaddition reaction upon irradiation with specific wavelengths in the UV region, which is applied to impart intrinsic healability, shape-memory, and reversible properties into polymers. In addition, coumarin chromophores are able to dimerize under the exposure to direct sunlight, which is a promising route for the synthesis and cross-linking of polymer systems under “green” and environment-friendly conditions. Along with the chemistry and design of coumarin functional polymers, we highlight various future application fields of coumarin containing polymers involving tissue engineering, drug delivery systems, soft robotics, or 4D printing applications.

An ultra-thin natural-source-based cellulose derivate is used in a bilayer gate dielectric for organic complementary inverters. Extraordinarily high small-signal gains up to 1600, a very sharp transition region (as low as 40 mV), a full rail-to-rail swing, a balanced noise margin of 92.5%, and “long-time” stability are shown, revealing that these inverters are highly suitable for complex circuit designs.

We report on the natural source based and biodegradable material cellulose on Al₂O₃ as ultrathin hybrid high-k dielectric layer for applications in green electronics. Dielectric films of 16 nm cellulose (ε ≈ 8.4) and 8 nm Al₂O₃ (ε ≈ 9) exhibit low leakage currents up to electric fields of 1.5 MV/cm. Pentacene and C₆₀ based organic thin film transistors show a well-balanced performance with operation voltages around 2 V. They are implemented in complementary inverters with excellent switching behavior, a small-signal gain up to 60 and with exceptionally high and balanced noise margin values of 82% at ultralow operation voltage (V_DD = 2.5 V).