The following article introduces technologies that build three dimensional (3D) objects by adding layer-upon-layer of material, also called additive manufacturing technologies. Furthermore, most important features supporting the conscious choice of 3D printing methods for applications in micro and nanomanufacturing are covered. The micromanufacturing method covers photopolymerization-based methods such as stereolithography (SLA), digital light processing (DLP), the liquid crystal display–DLP coupled method, two-photon polymerization (TPP), and inkjet-based methods. Functional photocurable materials, with magnetic, conductive, or specific optical applications in the 3D printing processes are also reviewed.
In this work, we presented a new bimolecular photoinitiating system based on 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives as visible photosensitizers of diphenyliodonium salt. Real-time FTIR and photo-DSC photopolymerization experiments with a cycloaliphatic epoxide and vinyl monomers showed surprisingly good reactivity of the bimolecular photoinitiating systems under UV-A, as well as under visible light sources. Steady-state photolysis, fluorescence experiments, theoretical calculations of molecular orbitals, and electrochemical analysis demonstrated photo-redox behavior as well as the ability to form initiating species via photo-reduction or photo-oxidation pathways, respectively. Therefore, the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives were also investigated as a type II free-radical photoinitiator with amine. It was confirmed that the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives, in combination with different types of additives, e.g., amine as a co-initiator or the presence of onium salt, can act as bimolecular photoinitiating systems for cationic, free-radical, and thiol-ene photopolymerization processes by hydrogen abstraction and/or electron transfer reactions stimulated by either near-UV or visible light irradiation. Finally, the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives were selected for 3D printing rapid prototyping experiments. Test objects were successfully printed using purely cationic photosensitive resin, created on a 3D printer with a visible LED light source.
27 November 2023 in Macromolecular Rapid Communications
A straightforward approach is employed to synthesize methylene‐bridged poly(hetero aromatic)s based on furan, pyrrole, thiophene, and thiophene derivatives. The process involves an electrophilic aromatic substitution reaction facilitated by a visible light‐initiated system consisting of manganese decacarbonyl and an iodonium salt. The approach mainly relies on the formation of halomethylium cation, the attack of this cation to heteroaromatic, regeneration of methylium cation on the heteroaromatic, and reactivity differences between halomethylium and heteroaromatic methylium cations for successful polymerizations. This innovative synthetic strategy lead to the formation of polymers with relatively high molecular weights as the stoichiometric imbalance between the comonomers increased. Accordingly, these newly obtained polymers exhibit remarkable fluorescence properties, even at excitation wavelengths as low as 330 nm. Moreover, by harnessing the halogens at chain ends of homopolymers, block copolymers are successfully synthesized, offering opportunities for tailored applications in diverse fields.
The following article introduces technologies that build 3 dimensional (3D) objects by adding layer-upon-layer of material, called also additive manufacturing technologies. Furthermore most important features supporting the conscious choice of 3D printing methods for applications in micro and nanomanufacturing were covered. The micromanufacturing method covers photopolymerisation based methods such as Stereolithography (SLA), Digital Light Processing (DLP), Liquid Crystal Display – DLP coupled method, Two-Photon Polymerisation (TPP) and Inkjet based methods. Functional photocurable materials, with magnetic, conductive or specific optical applications in the 3D printing processes were also reviewed.
Fluorescent molecular probes become interesting analytical tools in determination and labeling of chemical compounds and physical properties such as viscosity and polarity. Currently known fluorescent molecular probes can selectively and regardless of the environment detect only few molecules, and applicability in determination of micro- viscosity and micro-polarity are limited to narrow range and specific condition, therefore design and synthesis of novel molecular probes with extended range of operation are highly needed [1]. Traditional synthesis of 2-amino-4,6-diphenyl-pyridine-3-carbonitrile’s requires two step reaction with long heating time or and toxic solvent. By application of microwave irradiation, reaction time can be firmly shortened with the same or higher efficiency [2]. Derivatives of 2-amino-4,6-diphenyl-pyridine-3-carbonitrile can find application in different fields of science. Depending on the structure of fluorophore, those compounds exhibit high sensitivity to changes in polarity and viscosity of environment, also concentration of specific cations, and pH can be determined by measuring of fluorescence spectrum.