Shiwei Ren

An analytical method was established for the rapid determination of 45 pigments and preservatives in edible ink by ultra-high performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UHPLC-MS/MS), which provides technical support for the composition analysis and industrial development of edible ink. The samples were easily extracted with 75% aqueous methanol solution and purified with a Captiva EMR-Lipid HF solid-phase extraction cartridge. After filtration through a polytetrafluoroethylene (PTFE) membrane, the analytes were determined by UHPLC-MS/MS under multiple reaction monitoring (MRM) mode in both positive and negative ion modes. Poroshell 120 AQ-C18 was selected as the analytical column, and valve switching timing control was adopted during the gradient elution process. The external standard method was used for quantitative analysis. In the established method, the 45 pigments and preservatives exhibited good linear relationships within the mass concentration range of 0.0002–200.0 μg/mL. The limits of detection (LOD) and limits of quantification (LOQ) were 0.0004–8.00 mg/kg and 0.001–20.00 mg/kg, respectively. Using 25% aqueous glycerol solution as the blank matrix, the recoveries of analytes at different spiked levels met the detection requirements. The established method is simple and rapid, and can be applied to the qualitative and quantitative detection of typical pigments and preservatives in edible ink.

Synthèse de nouveaux semi-conducteurs organiques fonctionnels conjugués π pour des applications optoélectroniques: L'électronique organique est un domaine en plein essor, à l’interface de l’électronique, de la physique de la matière condensée, de la physico-chimie, et de la chimie organique. La découverte et le développement de nouveaux semi-conducteurs organiques ouvrent de nouvelles perspectives tant en sciences fondamentales qu’en termes d’applications. Ce travail décrit le développement de nouvelles voies de fonctionnalisation des systèmes p-conjugués en vue leurs applications potentielles comme semi-conducteur de type N. Le manuscrit est structuré en cinq chapitres, le premier fait un état de l'art récent sur la synthèse des semi-conducteurs organiques de type N. Le second chapitre décrit la synthèse et l'étude physico-chimique de quelques dérivés 7,7' isoindigo. Le troisième et le quatrième chapitre de ce travail décrit la synthèse d'une série de molécules A-D-A en modifiant les conditions classiques de la synthèse de l’indophénine et la mise au point de deux nouvelles voies de fonctionnalisation des dérivés de l’indophénine. Des études spectroscopiques et électrochimiques ont pu être menées, notamment afin de déterminer les énergies des orbitales frontières de nos molécules. Enfin, en dernier chapitre une étude exploratoire sur les propriétés de détection sélective de différents bactérie avec des polymères conjugués à conduction mixte a été entreprise.

The design of novel acceptor molecular structures based on classical building blocks is regarded as one of the efficient ways to explore the application of organic conjugated materials in conductivity and electronics. Here, a novel acceptor moiety, thiophene-vinyl-diketopyrrolopyrrole (TVDPP), was envisioned and prepared with a longer conjugation length and a more rigid structure than thiophene-diketopyrrolopyrrole (TDPP). The brominated TVDPP can be sequentially bonded to trimethyltin-containing benzo[c][1,2,5]thiadiazole units via Suzuki polycondensation to efficiently prepare the polymer PTVDPP-BSz, which features high molecular weight and excellent thermal stability. The polymerization process takes only 24 h and eliminates the need for chlorinated organic solvents or toxic tin-based reagents. Density functional theory (DFT) simulations and film morphology analyses verify the planarity and high crystallinity of the material, respectively, which facilitates the achievement of high carrier mobility. Conductivity measurements of the polymeric material in the organic transistor device show a hole mobility of 0.34 cm² V⁻¹ s⁻¹, which illustrates its potential for functionalized semiconductor applications.

Because of the complex nonlinear relationship between working conditions, the prediction of tribological properties has become a difficult problem in the field of tribology. In this study, we employed three distinct machine learning (ML) models, namely random forest regression (RFR), gradient boosting regression (GBR), and extreme gradient boosting (XGBoost), to predict the tribological properties of polytetrafluoroethylene (PTFE) composites under high-speed and high-temperature conditions. Firstly, PTFE composites were successfully prepared, and tribological properties under different temperature, speed, and load conditions were studied in order to explore wear mechanisms. Then, the investigation focused on establishing correlations between the friction and wear of PTFE composites by testing these parameters through the prediction of the friction coefficient and wear rate. Importantly, the correlation results illustrated that the friction coefficient and wear rate gradually decreased with the increase in speed, which was also proven by the correlation coefficient. In addition, the GBR model could effectively predict the tribological properties of the PTFE composites. Furthermore, an analysis of relative importance revealed that both load and speed exerted a greater influence on the prediction of the friction coefficient and wear rate.

Oligomers and polymers consisting of multiple thiophenes are widely used in organic electronics such as organic transistors and sensors because of their strong electron-donating ability. In this study, a solution to the problem of the poor solubility of polythiophene systems was developed. A novel π-conjugated polymer material, PDPP-5Th, was synthesized by adding the electron acceptor unit, DPP, to the polythiophene system with a long alkyl side chain, which facilitated the solution processing of the material for the preparation of devices. Meanwhile, the presence of the multicarbonyl groups within the DPP molecule facilitated donor–acceptor interactions in the internal chain, which further improved the hole-transport properties of the polythiophene-based material. The weak forces present within the molecules that promoted structural coplanarity were analyzed using theoretical simulations. Furthermore, the grazing incidence wide-angle X-ray scanning (GIWAXS) results indicated that PDPP-5Th features high crystallinity, which is favorable for efficient carrier migration within and between polymer chains. The material showed hole transport properties as high as 0.44 cm² V⁻¹ s⁻¹ in conductivity testing. Our investigations demonstrate the great potential of this polymer material in the field of optoelectronics.