RESUMEN
Colorless, transparent, and mechanically robust aramid polymers are synthesized from two diamine monomers with strong electron-withdrawing groups, using low-temperature solution condensation with diacid chloride. The aramids dissolved very well in the liquid acrylamide monomers. When N,N-dimethylacrylamide (DMA) is used as a reactive diluent, films with the desired features are produced from the hybrid aramid-DMA resins via ultraviolet (UV) curing. The hybrid films are colorless and transparent in the visible region and showed an increase in the glass transition temperature, tensile strength, and elastic modulus in proportion to the aramid content. Laminated glass is manufactured using the hybrid resin as an interlayer, which exhibits very strong adhesion between the two sheets of glass, is not easily broken by an external impact, and do not scatter fragments. Moreover, the laminated glass do not distort images and functioned very effectively in UV blocking, soundproofing, and suppressing changes in the ambient temperature. Heat treatment further improves the light transmittance and impact resistance of the laminated glass. Laminated glass specimens with various fluorescence colors are also manufactured. Aramid-reinforced films prepared using N,N-diethylacrylamide as a reactive diluent underwent thermally induced phase separation in a wet state, providing smart glass with a privacy protection function.
RESUMEN
The Sonogashira coupling reaction was used to synthesize a fluorenone derivative, with an extended conjugated structure to which fluorene is connected via acetylene linkage. This compound exhibited diverse fluorescence (FL) colors in the visible region depending on the polarity of the matrix solvents used. The solvatochromic FL presented as sky blue, green, and yellow in hexane, THF, and DMF, respectively. Fluorene moiety and fluorenone moiety acted as an electron donor (D) and as an electron acceptor (A), respectively, leading to an excited state intramolecular charge transfer based on the D-π-A electronic structure. In particular, this derivative showed a remarkable FL quenching in alcohol and chloroform, probably due to vibronic coupling through hydrogen bonding with these solvents. This idea was supported by the fact that the two solvents are characterized by very high hydrogen bond donor acidities compared to other solvents used in this study. This derivative also responded to the presence of very small amounts of water at several mg/mL levels in organic solvents, resulting in remarkable FL quenching.
RESUMEN
In this study, we synthesized three novel acrylic monomers with a cinnamate group. We then mixed each monomer with 2-hydroxyethyl methacrylate (HEMA) to prepare soft contact lenses through bulk polymerization. Fourier transform infrared (FT-IR) and UV spectral analyses confirmed that the cinnamate group in the polymer undergoes a photodimerization reaction via UV irradiation. After UV curing, the present lenses stably maintained their shapes even in a water-swollen state and showed significantly improved mechanical properties compared to conventional lenses manufactured using a cross-linking agent. These lenses showed slightly lower water contact angles than the conventional lenses, although the water content was slightly reduced. The present photodimerization cross-linking method was found to be useful in reducing the tearability of soft lenses.
RESUMEN
In this study, a chalcone-branched polyimide (CB-PI) was synthesized by the Steglich esterification reaction for selective recognition of the toxic peptide melittin (MEL). MEL was immobilized on a nanopatterned poly(dimethylsiloxane) (PDMS) mold using a conventional surface modification technique to increase binding sites. A stripe-nanopatterned thin CB-PI film was formed on a quartz crystal (QC) substrate by simultaneously performing microcontact printing and ultraviolet (UV) light dimerization using a MEL-immobilized mold. The surface morphology changes and dimensions of the molecularly imprinted polymer (MIP) films with stripe nanopatterns (S-MIP) were analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The sensing signals (Δf and Qe) of the S-MIP sensor were investigated upon adsorption in a 100-µL dilute plasma solution containing 30 µg/mL MEL, and its reproducibility, reuse, stability, and durability were investigated. The S-MIP sensor showed high sensitivity (5.49 mL/mg) and coefficient of determination (R2 = 0.999), and the detection limit (LOD) and the quantification limit (LOQ) were determined as 0.3 and 1.1 µg/mL, respectively. In addition, the selectivity coefficients (k*) calculated from the selectivity tests were 2.7-5.7, 2.1-4.3, and 2.8-4.6 for bovine serum albumin (BSA), immunoglobulin G (IgG), and apamin (APA), respectively. Our results indicate that the nanopatterned MIP sensors based on CB-PI demonstrate great potential as a sensing tool for the quantitative analysis of biomolecules.
Asunto(s)
Chalconas , Impresión Molecular , Impresión Molecular/métodos , Meliteno , Tecnicas de Microbalanza del Cristal de Cuarzo/métodos , Reproducibilidad de los Resultados , Polímeros/químicaRESUMEN
Conjugated polyelectrolytes (CPEs) are emerging as promising materials in the sensor field because they enable high-sensitivity detection of various substances in aqueous media. However, most CPE-based sensors have serious problems in real-world application because the sensor system is operated only when the CPE is dissolved in aqueous media. Here, the fabrication and performance of a water-swellable (WS) CPE-based sensor driven in the solid state are demonstrated. The WS CPE films are prepared by immersing a water-soluble CPE film in cationic surfactants of different alkyl chain lengths in a chloroform solution. The prepared film exhibits rapid, limited water swellability despite the absence of chemical crosslinking. The water swellability of the film enables the highly sensitive and selective detection of Cu2+ in water. The fluorescence quenching constant and the detection limit of the film are 7.24 × 106 L mol-1 and 4.38 nM (0.278 ppb), respectively. Moreover, the film is reusable via a facile treatment. Furthermore, various fluorescent patterns introduced by different surfactants are successfully fabricated by a simple stamping method. By integrating the patterns, Cu2+ detection in a wide concentration range (nM-mM) can be achieved.
RESUMEN
Noncovalent chemistry may offer diversity in the functions and applications for artificial polymers by allowing various ordered-disordered phase transitions in a precisely controlled manner. To verify this notion from a fundamental perspective, we examined an achiral poly(phenylacetylene) derivative with an α-helical structure as a helical-spring polymer for revealing phase changes through control of intramolecular hydrogen bonding with the chiral solvent and temperature. When an amine capable of hydrogen bonding was used as the chiral solvent, either an irreversible helix-helix or a reversible helix-coil phase change occurred in an optically dissymmetric manner according to the amount of the chiral solvent added and ambient temperature. Considering the hydrogen-bonding strength values of the solvent mixture and the thermodynamic parameters, we could predict if the optical-dissymmetry phase changes would occur and, if so, how they occur. Our results were similar to those see for the denaturation of proteins, induced by solvent and temperature, based on helix-coil phase transition.