Optically transparent, organosoluble poly(ether-amide)s bearing triptycene unit; synthesis and characterization

Studies on Loading Salicylic Acid in Xerogel Films of Crosslinked Hyaluronic Acid

During the last decades, salicylic acid (SA) and hyaluronic acid (HA) have been studied for a wide range of cosmetic and pharmaceutical applications. The current study investigated the drug loading potential of SA in HA-based crosslinked hydrogel films using a post-loading (osmosis) method of the unmedicated xerogels from saturated aqueous solutions of salicylic acid over a range of pH values. The films were characterized with Fourier-transform infra-red spectroscopy (FT-IR) and ultraviolet-visible (UV-Vis) spectrophotometry in order to elucidate the drug loading profile and the films' integrity during the loading process. Additional studies on their weight loss (%), gel fraction (%), thickness increase (%) and swelling (%) were performed. Overall, the studies showed significant film disintegration at highly acidic and basic solutions. No drug loading occurred at neutral and basic pH, possibly due to the anionic repulsion between SA and HA, whereas at, pH 2.1, the drug loading was promising and could be detected via UV-Vis analysis of the medicated solutions, with the SA concentration in the xerogel films at 28% w/w.

Simultaneous Treatment of Both Sides of the Polymer with a Conical-Shaped Atmospheric Pressure Plasma Jet

A conical-shaped atmospheric pressure plasma jet (CS-APPJ) was developed to overcome a standard limitation of APPJs, which is their small treatment area. The CS-APPJs increase the treatment area but use the same gas flow. In the present work, polypropylene samples were treated by CS-APPJ and characterized by scanning electron microscope (SEM), the contact angle, Fourier-transformed infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). It was observed that the treatment co-occurs on the face directly in contact with the plasma and on the opposite face (OF) of the samples, i.e., no contact. However, the treatment changed the chemical composition on each side; the OF is rougher than the direct contact face (DCF), probably due to the oxygen groups in excess at the DCF and nitrogen in quantity at the OF. Although simultaneous treatment of both sides of the sample occurs for most atmospheric plasma treatments, this phenomenon is not explored in the literature.

Quantum Dot-Induced Blue Shift of Surface Plasmon Spectroscopy

We experimentally demonstrate the spectral blue shift of surface plasmon resonance through the resonant coupling between quantum dots (QDs) and surface plasmons, surprisingly in contrast to the conventionally observed red shift of plasmon spectroscopy. Multimode optical fibers are used for extended resonant coupling of surface plasmons with excited states of QDs adsorbed to the plasmonic metal surface. The long-lived nature of excited QDs permits QD-induced negative change in the local refractive index near the plasmonic metal surface to cause such a blue shift. The analysis utilizes the physical causality-driven optical dispersion relation, the Kramers-Kronig (KK) relation, attempting to understand the abnormal behavior of the QDs-induced index dispersion extracted from blue shift measurement. Properties of QDs' gain spectrally resonating with plasmons can account for such blue shift, though their absorbance properties never allow the negative index change for the blue shift observed according to the KK relation. We also discuss the limited applicability of the KK relation and possible QDs gain saturation for the experiment-theory disagreement. This work may contribute to the understanding of the photophysical properties critical for plasmonic applications, such as plasmonic local index engineering required in analyte labeling QDs coupled with plasmons for biomedical imaging or assay.

Synthesis and characterization of new aromatic copoly(ether amide)s bearing 4-trifluoromethylphenyl-2,6-diphenylpyridyl moieties in the main chain

A series of new aromatic fluorinated copoly(ether amide)s containing 4-(4-trifluoromethylphenyl)-2,6-diphenylpyridyl moiety with high molecular weight were prepared by a low-temperature solution polycondensation of terephthaloyl chloride with 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene with various mole ratios of the two monomers ranged from 20/80 to 80/20. All polymers were amorphous and soluble in common organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide and tetrahydrofuran at room temperature or upon heating at 70oC, and could be solution cast into transparent, tough, and flexible films with tensile strengths of 66.9–80.2 MPa, tensile moduli of 1.84–2.03 GPa, and elongations at break of 11.8–20.7%. These new polyamides displayed good thermal stability with gradually increasing of glass temperatures of 259–285oC as an increase of the 4-(4-trifluoromethylphenyl)-2,6-diphenylpyridyl component, the temperature at 10% weight loss of 476–505oC, and the residue of 55–61% at 750oC in nitrogen. They also exhibited low dielectric constants of 3.11–3.38 (1 MHz), low moisture absorption in the range of 1.43–1.75%, and high transparency with an UV–vis absorption cut-off wavelength in the 350–368 nm range.

New soluble, transparent and heat-resistant poly(ether amide)s based on 10,10-bis[4-(4-aminophenoxy)-3-methylphenyl]-9(10H)-anthrone

10,10-Bis[4-(4-aminophenoxy)-3-methylphenyl]-9(10 H)-anthrone, as a new aromatic diamine, was synthesized from 9(10 H)-anthrone by three-step procedure. Low-temperature polycondensation of this diamine with various aromatic dicarboxylic acid dichlorides produced a series of new cardo poly(ether amide)s with moderate to high inherent viscosities of 0.86–1.43 dL g−1 while the weight-average and number-average molecular weights were in the range of 48,600–59,800 and 29,800–35,600 g mol−1, respectively. All the polymers were readily soluble in polar solvents such as N, N-dimethylacetamide (DMAc), N, N-dimethylformamide, N-methyl-2-pyrrolidinone, dimethyl sulfoxide, and pyridine, and afforded transparent, flexible, and strong films upon casting from DMAc solvent. These polymers had glass transition temperatures of 254–297°C, 10% weight loss temperatures of 493–505°C, and char yields of 61–64% at 800°C in nitrogen. All polymers were amorphous and their films exhibited tensile strength of 80.7–101.4 MPa, elongation at break of 8.0–12.8%, and tensile modulus of 1.9–2.6 GPa. These polymers had low moisture uptake in the range of 2.13–4.02% and high transparency with an ultraviolet–visible absorption cutoff wavelength in the 322–375 nm range.