Effect of Thermal Treatment on the Properties of TEMPO Oxidized Cellulose Film for the Flexible Substrate of Solar Cell

The 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO)oxidized cellulose film(TOCF)has been attempted to be used as a substrate in electronic and optoelectronic devices,but the changes in the TOCF properties before and after annealing treatment have usually been neglected during device fabrication.In this study,TOCF was treated in different atmospheres(air,vacuum,and N2)and at different temperatures,and the properties were investigated.The results indicate that the optical properties are slightly affected by atmosphere and temperature;only slight transmittance loss and haze increase have been observed when TOCF is exposed to an air atmosphere at temperatures of above 120℃.In contrast to the slight effects on the optical properties,cellulose degradation and a loss of film strength have been observed regardless of the atmosphere used when placed at temperatures of above 100℃.Specifically,TOCF was exposed to air,followed by N2 and vacuum atmospheres.Additional Fourier transform infrared(FT-IR)and nuclear magnetic resonance(NMR)results showed that increasing the temperature had no significant effect on the structure of TOCF.Therefore,the annealing temperature should be controlled at a temperature of lower than 100℃and a vacuum atmosphere is preferred.

The Adsorption Properties of TEMPO Oxidized Cellulose against the Mixture of Methylene Blue and Rhemazol Yellow FG

TEMPO/NaOCl/NaBr treatment significantly increased the number of negative charges on the cellulose surface.Two concentrations of NaOCl,5 and 30 mmol/g of cellulose,were used in this study.The number of carboxyl groups in the two cellulosic samples oxidized using TEMPO/NaOCl/NaBr was 0.5160 and 1.8461 mmol/g of cellulose,respectively.The oxidized cellulose samples treated with 5 and 30 mmol/g NaOCl exhibited higher crystallinity,at 81.15%and 80.14%,respectively,compared to untreated cellulose,which had a crystallinity of 75.95%.The pH effect indicated that the highest adsorption capacity for methylene blue was achieved under alkaline conditions(pH 9),while the highest adsorption capacity for rhemazol yellow FG was achieved under acidic conditions.The kinetic model of TEMPO-oxidized cellulose for methylene blue and rhemazol yellow FG conformed to the pseudo-second-order model.The initial concentration parameter revealed that the isotherm model for the adsorption of methylene blue and rhemazol yellow FG by TEMPO-oxidized cellulose conformed to the Langmuir model.The dye removal efficiencies for methylene blue and rhemazol yellow FG using TEMPOoxidized cellulose(30 mmol/g)were approximately 80.17%and 59.52%,respectively.These results demonstrate that TEMPO/NaOCl/NaBr-oxidized samples can effectively separate cationic and anionic dye mixtures.Furthermore,the use of TEMPO-oxidized cellulose showed good regeneration capability,maintaining more than 95%of its adsorption capacity after 8 cycles.

Stable Radical TEMPO Terminated Perylene Bisimide(PBI) Based Small Molecule as Cathode Interlayer for Efficient Organic Solar Cells

By combining stable radical tetramethylpiperidine nitrogen oxide(TEMPO)as end groups and perylene bisimide(PBI)as the core,a small molecular cathode interlayer(CIL)(PBI-TEMPO)was synthesized.Detailed physical-chemical characterizations indicate that PBI-TEMPO can form smooth film,owns low unoccupied molecular orbital(LUMO)level of−3.67 eV and can reduce the work function of silver electrode.When using PBI-TEMPO as CIL in non-fullerene organic solar cells(OSCs),the PM6:BTP-4Cl based OSCs delivered high power conversion efficiencies(PCEs)up to 17.37%,higher than those using commercial PDINO CIL with PCEs of 16.95%.Further device characterizations indicate that PBI-TEMPO can facilitate more efficient exciton dissociation and reduce charge recombination,resulting in enhanced current density and fill factor.Moreover,PBI-TEMPO displays higher thermal stability than PDINO in solution.When PBI-TEMPO and PDINO solution were heated at 150℃ for 2 h and then were used as CIL in solar cells,PBI-TEMPO-based OSCs provided a PCE of 15%,while PDINO-based OSCs only showed a PCE of 10%.These results demonstrate that incorporating TEMPO into conjugated materials is a useful strategy to create new organic semiconductors for application in OSCs.

Construction of Multi-Substituted Benzenes via NHC-Catalyzed Reactions of Carboxylic Esters

A carbene-catalyzed ester activation reaction for the synthesis of multi-substituted benzenes is developed. Tetra-substituted benzene com- pounds are efficiently synthesized through this methodology. Compared with aldehyde substrates used in previous reports, the ester substrates used here are much more readily available and inexpensive. In addition, the TEMPO oxidant used here is more inexpensive than the quinones commonly used in related carbene-catalyzed reactions.

Effects of chitin nanocrystals on coverage of coating layers and water retention of coating color

This study assessed the applicability of chitin nanocrystals prepared by 2,2,6,6-Tetramethyl-1-Piperidine-1-oxyl radical(TEMPO)-mediated oxidation in traditional papermaking coating color systems.The𝛼-chitin nanocrystals(CTNCs)with different carboxyl content,size,and morphology were prepared from crab shells by alkali pretreatment and TEMPO-mediated oxidation in the water at pH 10,and then the ratio of CTNCs to latex was applied to traditional coating color system to replace part of latex.The results showed that when the amount of NaClO added as co-oxidant in the oxidation was 15.0 mmol/g of chitin,the carboxyl content of alkali-pretreated CTNCs was up to 0.76 mmol/g.The amount of carboxyl groups presented a linear relation with the degree of individualization of nanocrystals and dispersion.When the ratio of latex to CTNCs was 90꞉10,the water retention value of the coating was 92%lower than that of the pure latex system,and the rheological property was better.The relationship between the addition amount of CTNCs and the surface strength and the coverage of coating layers were also studied,and results showed that when the ratio of latex to CTNCs was 95꞉5,the surface strength was the highest of 1.45 m/s,and the coverage of coating layers rate reached the highest of 78%.