Microlenses are highly sought as reliable means for high-resolution optical imaging at low illumination intensities. Plano-convex configuration with tunable dimension and curvature is an essential feature in the microlens fabrication. In this study, we present a facile and green route for preparing well-defined microlenses based on polymer phase separation in the presence of supercritical carbon dioxide (scCO2). The behaviors of linear polymethylmethacrylate protruded from cross-linked silicone network in scCO2 environment are investigated from the perspectives of thermodynamics and kinetics. Microlenses with dimensions from 2 to 15 μm and contact angles from 55° to 112° are successfully obtained through the adjustment of the kinetic conditions and outgassing rate. With the tunable focal length, they exhibit intrinsic function of discerning submicroscale patterns that are unable to be observed directly under optical microscope. Moreover, size confinement on the substrate results in the generation of well-ordered microlens arrays, affording great promise for applications in bioimaging, photolithography, light harvesting, and optical nanosensing.Keywords: microlens; microlens array; polymer phase separation; supercritical carbon dioxide; variable focal length

The hybrid films of reinforcing the aged papers have been employed via layer-by-layer (LBL) assembly deposition of the chitosan lactate/carboxymethyl cellulose complex previously modified with metal oxide. In order to reinforce the films, a vacuum infiltration was adopted in the LBL process. The mechanical properties and structure of the aged papers in relation to fiber morphology were investigated using SEM, FTIR, XPS, and tensile test. The well-dispersed coatings resulted in an excellent improvement in mechanical properties of the modified paper. After only three bilayers deposited, the measured tensile strength and folding endurance for modified aged newspaper samples increased up to 100% and 450%, respectively, as compared to the control sample. This high efficiency was kept even when the modified paper samples exposed to the moist-heat accelerated aging and UV irradiation. The pH of the paper rose to alkalescence rapidly, and the paper samples maintained their coloration close to the original after treatment.

Potassium methyl siliconate (PMS) was investigated as a simple physicochemical modification in aged paper using silane coupling technique. The PMS-based solution was shown to favor penetration in the cellulose fibers on the paper with suitable uptakes being achieved at low concentrations. The studies of the physicochemical properties of the treated paper (mechanical strength and alkalinity) demonstrated that, besides the required deacidification feature and high level of alkali reserves, the immersion treatment by PMS allowed the enhancement of the mechanical intensities of paper arising from the interaction between Si―OH generated in hydrolysis of PMS and C―OH of cellulose on the paper. Adding ethanol into PMS solution could significantly improve mechanical properties of the aged paper treated by the formula apart from modifying the flatness of the paper. Optimized treatment process was achieved by altering the ratio of ethanol to water in PMS-based solutions. Contact angle measurements indicated the occurrence of hydrophobic character of the papers in immersion treatment with PMS-based solutions. The easy availability of the materials and simplicity of the method rendered it convenient for treatment for aged paper documents.

In this work we have reported the formulation of a CO2-based micelle stabilized by nontoxic TMN series surfactants. Enantioselection of racemic ibuprofen catalyzed by Candida antarctica lipase B (CALB) was used as a model reaction. The effect of reactive parameters, such as temperature, pH, pressure, and water content on reactive environment and conversion has been discussed. For the resolution of racemic ibuprofen in CO2-based micelles, the enzymatic activity reached a high level at 45 °C, with pressure 250 bar, pH 7.4, and water to surfactant ratio W0 25. In addition, the relatively long-chain length in TMN-10 could help the esterification and trans-esterification processes, which resulted in an efficient reaction rate in a CO2-based micelle system. Enzymatic catalysis has been conducted in a CO2-based system rather than in the conventional media to make the enzyme reaction greener. The better resolution efficiency in high pressure CO2-based micelles could be achieved within a relatively short period of time compared with other traditional reactive systems.

A CO2-based micellar system stabilized by nonionic methylated branched hydrocarbon surfactants was used as a microreactor for the ligand-free Suzuki reaction involving the cross-coupling of iodobenzene and 4-methylbenzeneboronic acid to produce p-methyl biphenyl. In the reaction system, the nonionic surfactant (TMN series) acted both as the reducing agent and as the stabilizer of the palladium nanoparticles that were generated. Transmission electron microscopy images demonstrated that the uniform and nanoscale Pd particles with a sharp size distribution were formed in the CO2-based micelle. The effects of reaction parameters, such as surfactant concentration, CO2 pressure, water content, and base selection, on the microenvironment and conversion in CO2-based microemulsion and emulsion are discussed. In this work, we compared the reactivity in different reactive systems including pure water, atmospheric water–cyclohexane microemulsion, and CO2-based microemulsion. Activity in the CO2-based microemulsion was higher than that obtained with the other two catalytic systems. In these processes, the organic base played a role similar to that of the interface phase-transfer catalyst. These synergistic effects could effectively accelerate the reaction.

The investigation of the effect of micro impurity on crystal growth by optical microscopy has been validated. The results showed that the growth rate of a lysozyme crystal was affected even if the concentration of impurity of fluorescent-labeled lysozyme (abbreviation, F-lysozyme) was very small. Different concentrations of F-lysozyme had different effects on crystal growth rate. The growth rate decreased much more as F-lysozyme concentration increased. The density of incorporated F-lysozyme on different grown layers of a lysozyme crystal during crystal growth was obtained from the results of flat-bottomed etch pits density.