Lithography-based additive manufacturing was introduced in the 1980s, and is still the method of choice for printing accurate plastic parts with high surface quality. Recent progress in this field has made tough photopolymer resins and cheap LED light engines available. This study presents the influence of photoinitiator selection and post-processing on the thermomechanical properties of various tough photopolymers. The influence of three photoinitiators (Ivocerin, BAPO, and TPO-L) on the double-bond conversion and mechanical properties was investigated by mid infrared spectroscopy, dynamic mechanical analysis and tensile tests. It was found that 1.18 wt % TPO-L would provide the best overall results in terms of double-bond conversion and mechanical properties. A correlation between double-bond conversion, yield strength, and glass transition temperature was found. Elongation at break remained high after post-curing at about 80-100%, and was not influenced by higher photoinitiator concentration. Finally, functional parts with 41 MPa tensile strength, 82% elongation at break, and 112 °C glass transition temperature were printed on a 405 nm DLP (digital light processing) printer.
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http://dx.doi.org/10.3390/ma10121445 | DOI Listing |
Nat Commun
January 2025
State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Haihe Laboratory of Sustainable Chemical Transformations, Nankai University 94 Weijin Road, Tianjin, China.
The diverse utility of acyclic vinylsilanes has driven the interest in the synthesis of enantioenriched vinylsilanes bearing a Si-stereogenic center. However, the predominant approaches for catalytic asymmetric generation of Si-stereogenic vinylsilanes have mainly relied on transition metal-catalyzed reactions of alkynes with different silicon sources. Here we successfully realize the enantioselective synthesis of linear silicon-stereogenic vinylsilanes with good yields and enantiomeric ratios from simple alkenes under rhodium catalysis.
View Article and Find Full Text PDFThe hexadehydro-Diels-Alder (HDDA) reaction is a cycloisomerization between a conjugated diyne and a tethered diynophile that generates -benzyne derivatives. Considerable fundamental understanding of aryne reactivity has resulted from this body of research. The multi-yne cycloisomerization substrate is typically pre-formed and the (rate-limiting) closure of this diyne/diynophile pair to produce the isomeric benzyne generally requires thermal input, often requiring reaction temperatures of >100 °C and times of 16-48 h to achieve near-full conversion.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Key Laboratory for Advanced Materials, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China.
Understanding and effectively controlling molecular conformational changes are essential for developing responsive and dynamic molecular systems. Here, we report that an oriented external electric field (OEEF) is an effective catalyst for the cis-trans isomerization of stiff-stilbene, a key component of overcrowded alkene-based rotary motors. This reversible isomerization occurs under ambient conditions, is free from side reactions, and has been verified using ultraperformance liquid chromatography and UV-vis absorption spectroscopy.
View Article and Find Full Text PDFRSC Adv
January 2025
State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences Taiyuan 030001 China
The research and development of the green synthesis route of chemicals has become the focus of research in academia and industry. At present, the highly efficient oxidation of ethanol to acetaldehyde over non-precious metal catalysts under mild conditions is most promising, but remains a big challenge. Herein, the Mo-Sn oxide catalyst was designed to successfully realize low-temperature oxidation of ethanol to acetaldehyde, achieving an acetaldehyde selectivity of 89.
View Article and Find Full Text PDFChem Asian J
December 2024
Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, 741246, Mohanpur, Nadia, India.
Amphiphilic dimeric cyanostilbenes with two donor-acceptor moieties connected through variable aliphatic linkers displayed aggregation in aqueous media to produce red emissive nano-assemblies. In the presence of anionic biopolymers such as ctDNA and heparin, they formed electrostatically driven co-assemblies with enhanced luminescence. Moreover, due to the chiral nature of the bio-templates DNA and heparin, the co-assemblies demonstrated induced chirality features.
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