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Oxidative Chemical Vapor Deposition for Conjugated Polymers: Theory and Applications
Published in John R. Reynolds, Barry C. Thompson, Terje A. Skotheim, Conjugated Polymers, 2019
Karen K. Gleason, Xiaoxue Wang
Researchers have demonstrated two type of low band gap semiconducting polymers, PITN49 and pSe,50 using oCVD technology. The chemical structure for both monomers can be found in Table 15.2. Borrelli et al. first reported a single-step oCVD method to synthesize PITN, using 1,3-dihydroisothianaphthene (DHITN) and FeCl3 as the precursors.49 Similar to other conjugated polymers, PITN also exhibits the quinoid-benzoid structural resonation. With the large benzene ring fused on the 3 and 4 position of the thiophene ring, the quinoid structure is preferred in its neutral state, significantly different from its parent polymer polythiophene. As a result, the band bap of PITN is almost half of polythiophene, making neutral PITN a dark blue thin film with low band gap. In addition, the heavily doped PITN is transparent; therefore the drastic color difference between the doped and neutral states makes PITN a good candidate for electrochromic applications.
Understanding the evolution of a de novo molecule generator via characteristic functional group monitoring
Published in Science and Technology of Advanced Materials, 2022
Takehiro Fujita, Kei Terayama, Masato Sumita, Ryo Tamura, Yasuyuki Nakamura, Masanobu Naito, Koji Tsuda
We proposed CFGM in this paper and showed that it can elucidate strategic evolution of a DNMG and suggest an unconventional chromophore. In our experiments, ChemTS found light-absorbing molecules only from empirical observations without any knowledge of quantum chemical foundation. Early-day chemists in the 19th century did not have such knowledge either. It is intriguing that the strategy learned by ChemTS is reminiscent of Armstrong’s quinoid theory [32] established in 1887. It states that only the compounds written in a quinoid form are coloured. Obviously, it is too simplistic and wrong in the eyes of current-day chemists. In the research of artificial intelligence, it is a widely asked question if AI ‘thinks’ like humans or how to make AI behave like humans [33]. The observation that ChemTS behaved like a chemist in the 19th century is an encouraging sign for us. In future work, further integration of AI and quantum chemical knowledge may lead to a better system.
Colour changes of two thermoplastic resins used for flexible partial dentures
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2022
Margarida Sampaio-Fernandes, João Galhardo, Sandra Campos, Susana João Oliveira, José Carlos Reis-Campos, Roberto C. Stegun, Maria Helena Figueiral
The polymers studied have specific chemical properties that may account for the discolouration patterns observed. In fact, phenolic antioxidants, responsible for the greater stability, physical and thermal resistance of these polymers, react with free radicals, residual catalyst, humidity and heat, forming coloured quinoid compounds (usually yellow) (Hendrickson and Connole 1995; Kikuchi et al. 2013). On the other hand, due to the porosity of our samples, water absorption is inevitable. Water diffuses into the polymeric matrix, separates the monomer chains, thus changing the colour of the resin, usually making it whiter (lower L * value) (Hersek et al. 1999). This fact could explain the colour difference recorded in the control groups.