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The Impact of Polymer Grafting from a Graphene Oxide Surface on Its Compatibility with a PDMS Matrix and the Light-Induced Actuation of the Composites
摘要： Poly(dimethyl siloxane) (PDMS)-based materials with improved photoactuation properties were prepared by the incorporation of polymer-grafted graphene oxide particles. The modification of the graphene oxide (GO) surface was achieved via a surface initiated atom transfer radical polymerization (SI ATRP) of methyl methacrylate and butyl methacrylate. The modification was confirmed by thermogravimetric analysis, infrared spectroscopy and electron microscopy. The GO surface reduction during the SI ATRP was investigated using Raman spectroscopy and conductivity measurements. Contact angle measurements, dielectric spectroscopy and dynamic mechanical analyses were used to investigate the compatibility of the GO filler with the PDMS matrix and the influence of the GO surface modification on its physical properties and the interactions with the matrix. Finally, the thermal conductivity and photoactuation properties of the PDMS matrix and composites were compared. The incorporation of GO with grafted polymer chains, especially poly(n-butyl methacrylate), into the PDMS matrix improved the compatibility of the GO filler with the matrix, increased the energy dissipation due to the improved flexibility of the PDMS chains, enhanced the damping behavior and increased the thermal conductivity. All the changes in the properties positively affected the photoactuation behavior of the PDMS composites containing polymer-grafted GO.
关键词： grafting method,reversible deactivation radical polymerization,smart polymers
更新于2025-09-09 09:28:46
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Imaging as a Personalized Biomarker for Prostate Cancer Risk Stratification
摘要： Biomarkers provide objective data to guide clinicians in disease management. Prostate-specific antigen serves as a biomarker for screening of prostate cancer but has come under scrutiny for detection of clinically indolent disease. Multiple imaging techniques demonstrate promising results for diagnosing, staging, and determining definitive management of prostate cancer. One such modality, multiparametric magnetic resonance imaging (mpMRI), detects more clinically significant disease while missing lower volume and clinically insignificant disease. It also provides valuable information regarding tumor characteristics such as location and extraprostatic extension to guide surgical planning. Information from mpMRI may also help patients avoid unnecessary biopsies in the future. It can also be incorporated into targeted biopsies as well as following patients on active surveillance. Other novel techniques have also been developed to detect metastatic disease with advantages over traditional computer tomography and magnetic resonance imaging, which primarily rely on defined size criteria. These new techniques take advantage of underlying biological changes in prostate cancer tissue to identify metastatic disease. The purpose of this review is to present literature on imaging as a personalized biomarker for prostate cancer risk stratification.
关键词： magnetic resonance imaging (MRI),cancer staging,active surveillance,radical prostatectomy,Gleason score,radiation therapy
更新于2025-09-09 09:28:46
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Preparation and Surface Properties Study of Novel Fluorine-Containing Methacrylate Polymers for Coating
摘要： A new structural fluorine-containing methacrylate monomer CH2=C(CH3)COOC–(CF3)2CF2CF2CF3 (5) was synthesized derived from perfluoro-2-methyl-2-pentene (D2). A homopolymer of 5 and copolymers of 5 and methacrylate with different alkyl chain length (chain length n = 1, 2, 4, 6, 8, 12, 18) were obtained. These new fluorinated acrylate polymers showed excellent water and oil repellency. The contact angle of the films of the homopolymer and part of the copolymers were similar with the corresponding polymers prepared from CH2=CHC(O)OCH(C3F7)(CF(CF3)2), but greater than that of the C6F13(CF3)CHOC(O)CH=CH2 homopolymer. The structure-property relationship research indicated that the copolymers’ hydrophobicity decreased first and then increased with the increase of alkyl chain length. Td of all the polymers were greater than 220 ?C and Tg fluctuated within the range of ?51~103.8 ?C. Contact angle and Tg could be adjusted by controlling the feed ratio of monomer to meet the requirements of technical indicators in the practical applications. The outstanding liquid repellency and thermal stability make monomer 5 a promising alternative to perfluorinated long-chain fluorosurfactants.
关键词： free radical copolymerization,fluorine-containing methacrylate,thermal property,repellency,fluorocarbon coating
更新于2025-09-09 09:28:46
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Experimental and theoretical investigations of free radical photopolymerization: Inhibition and termination reactions
摘要： In this work, the inhibition and termination reactions occurring throughout a free radical photopolymerization initiated by a type-I photoinitiator are studied by kinetic modeling. The role of the macroradicals as the main oxygen trapping agents during the inhibition time is identified, and the absence of primary radical consumption by oxygen can be related to a high initiation efficiency at early times. The ratio of the termination reactions reveals that bimolecular termination remains the principal pathway for the cessation of macromolecule growth, even at high polymer conversion. Moreover, the evolution of the termination ratio during the polymerization can be correlated to both the diffusional control of the polymerization reactions as the polymer network grows and the photoinitiator consumption. Finally, the effect of the incident light intensity and the initial photoinitiator concentration on the termination reactions is assessed, and the validity of the steady-state assumption applied to the macroradical concentration discussed.
关键词： Oxygen inhibition,Kinetic modeling,Radical photopolymerization,Steady-state assumption,Type-I photoinitiator,Termination reactions
更新于2025-09-09 09:28:46
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P-1.10: Solution-processed metal oxide semiconductors fabricated with oxygen radical assisting perchlorate aqueous precursors through a new low-temperature reaction route
摘要： In this report, an innovative and simple chemical route for fabricating MO semiconducting low temperature without any fuel additives or special annealing methods is demonstrated. Different from combustion method, the precursor that we compound contains only two kinds of oxidizers. The precursor, which consisted of perchlorate, nitrate, and DI water, is easily converted into In2O3 at an annealing temperature of 250 °C due to oxygen radical assisting decomposition and large amount of heat generation. It is found that perchlorate salt can decompose and form oxide film with high quality at lower temperature when assisted by nitrate salt. The optimized In2O3-TFT fabricated at 250°C via this precursor exhibits a saturate mobility of 14.5 cm2V-1s-1. Furthermore, this approach has been expanded to fabrication films at 350°C and attained improved performance.
关键词： metal oxide semiconductor,perchlorate salt,solution-process,oxygen radical,Thin-film transistor
更新于2025-09-09 09:28:46
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[Polymers and Polymeric Composites: A Reference Series] Functional Polymers || Photo-polymerization
摘要： The synthesis of functional polymers by photopolymerization thrives on the rich tradition of industrial photochemistry. Photo-induced polymerization can be broadly divided based on the initiation mechanism as radical, cationic, and anionic photopolymerization. A wide variety of initiators, photosensitizers, and polymerizable materials have been studied for various applications. This chapter is intended to be a primer to major concepts of photopolymerization. In the beginning of the chapter, physical aspects of light matter interactions are presented followed by photochemical pathways leading to reactions. In the subsequent sections radical polymerization is discussed by introducing different types of initiating systems and polymerizable materials. Within the section on radical polymerization, visible light polymerization and thio-ene photochemistry are also discussed. The section on thiol-ene looks at the fundamentals of thiol-ene reactions, their initiation, reactivity, and advantages over other radical driven polymerizations. Cationic polymerization is covered based on the material science of ionic and nonionic photoacid generators (PAGs). This section also discusses spectral broadening of reactivity in PAGs to visible wavelengths through electron transfer sensitization and free radical promoted cationic polymerization (FRPCP). Unlike radical and cationic polymerization there are little or no reports of commercial application of anionic polymerization. However, due to typical monomers employed in anionic polymerization and the control over the extent of polymerization afforded by this techniques makes it very attractive for functional applications. The section on anionic polymerization summarizes recent developments in this field. Finally in the section about two-photon initiated polymerization, we discuss the scope of nonlinear optical phenomena in photopolymerization.
关键词： anionic polymerization,radical polymerization,two-photon absorption,photopolymerization,photoinitiators,photosensitizers,cationic polymerization
更新于2025-09-09 09:28:46
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Disubstituted Aminoanthraquinone-Based Photoinitiators for Free Radical Polymerization and Fast 3D Printing under Visible Light
摘要： The development of highly efficient and rapid photoinitiating systems for free radical photopolymerization under the irradiation of visible light has attracted increasing attention due to their widespread potential applications in, for example, 3D printing or dental polymers. Unfortunately, currently available visible-light-sensitive photoinitiators are not efficient enough for 3D printing applications suffering from low printing speeds. Here we describe a series of photoinitiating systems consisting of disubstituted amino-anthraquinone derivatives (i.e., 1-amino-4-hydroxy-anthraquinone, 1,4-diaminoanthraquinone, and 1,5-diamino-anthraquinone) and various additives (e.g., tertiary amine and phenacyl bromide) toward the free radical photopolymerization of various acrylate monomers (such as commercial 3D resin) under the irradiation of blue to red LEDs. It is shown that the type and position of substituents of the aminoanthraquinone derivative can significantly affect its photoinitiation properties. The most efficient disubstituted aminoanthraquinone derivative-based photoinitiating system was selected and used for the 3D printing of a commercial 3D resin in a 3D printer with polychromatic visible light as the irradiation source. It is shown that its printing speed was dramatically enhanced compared to a commercial photoinitiator 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO).
关键词： aminoanthraquinone derivatives,free radical photopolymerization,photoinitiating systems,visible light,3D printing
更新于2025-09-09 09:28:46
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A Dual-functional Superoxide Precursor to Improve the Electrical Characteristics of Oxide Thin Film Transistors
摘要： We investigated a method to simultaneously improve the mobility and reliability of solution-processed zinc tin oxide thin film transistors (ZTO TFTs) using a dual-functional potassium superoxide precursor. Potassium cations in the potassium superoxide (KO2) precursor act as carrier suppliers in the ZTO thin film to improve the carrier (electron) concentration, which allows the potassium-doped ZTO TFT to exhibit high mobility. The anions in the precursor exist as superoxide radicals that reduce oxygen vacancies during the formation of thin oxide film. Consequently, the KO2-treated ZTO TFTs exhibited improved mobility and reliability compared with pristine ZTO TFTs, with an increase in field effect mobility from 5.57 to 8.74 cm2/Vs and a decrease in the threshold voltage shift from 7.18 to 3.85 V, after a positive bias temperature stress test conducted over 5000 sec.
关键词： oxide semiconductor,superoxide radical,solution process,Dual-functional precursor,thin film transistor
更新于2025-09-09 09:28:46
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A vacuum ultraviolet photoionization time-of-flight mass spectrometer with high sensitivity for study of gas-phase radical reaction in a flow tube
摘要： Photoionization mass spectrometry as a powerful analytical method has been widely utilized and provided valuable insight in the field of gas-phase reactions. Here, a highly sensitive vacuum ultraviolet (VUV) photoionization time-of-flight mass spectrometer combined with a microwave discharge generator and a fast flow tube reactor has been developed to study radical reactions of atmospheric and combustion interests. Two kinds of continuous light sources, the tunable VUV synchrotron radiation at Hefei, China for isomer-specific product detection and a commercial krypton discharge lamp for time-consuming kinetic measurements, are employed as photoionization sources in the apparatus. A multiplexed detection with high sensitivity (the limit of detection ～0.8 ppb) and high mass resolution (M/ΔM ～ 2100) has been approached. As representative examples, the self-reaction of the methyl radical, CH3, and the reaction of the methyl radical with molecular oxygen are studied and multiple species including reactive radicals and isomeric/isobaric products are detected and identified. In addition, some preliminary results related to the reaction kinetics are also presented.
关键词： methyl peroxy radical,kinetics,flow tube,Photoionization mass spectrometer,methyl radical,radical reaction
更新于2025-09-04 15:30:14
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Free-radical gases on two-dimensional transition-metal disulfides (XS <sub/>2</sub> , X = Mo/W): robust half-metallicity for efficient nitrogen oxide sensors
摘要： The detection of single gas molecules is a highly challenging work because it requires sensors with an ultra-high level of sensitivity. By using density functional theory, here we demonstrate that the adsorption of a paramagnetic unpaired free radical gas (NO) on a monolayer of XS2 (X = Mo, W) can trigger the transition from semiconductor to half metal. More precisely, the single-layer XS2 (X = Mo, W) with NO adsorbed on it would behave like a metal in one spin channel while acting as a semiconductor in the other spin orientation. The half-metallicity is robust and independent of the NO concentration. In contrast, no half-metallic feature can be observed after the adsorption of other free radical gases such as NO2. The unique change in electronic properties after the adsorption of NO on transition-metal sulfides highlights an effective strategy to distinguish NO from other gas species by experimentally measuring spin-resolved transmission. Our results also suggest XS2 (X = Mo, W) nanosheets can act as promising nanoscale NO sensors.
关键词： sensors,nitric oxide (NO),free radical,half-metallicity,spin-polarized
更新于2025-09-04 15:30:14