A series of semi-interpenetrated polymer networks based on bisphenol A epoxy resin and polyurethane was synthesized by sequential procedure. The molecular dynamics of polyurethane incorporated in the resin network with increasing amounts of resin was followed by dynamic mechanical analysis. All phenomena that concur in the material are evaluated by cross-examination of the storage modulus (E 1 ), loss modulus (E 11 ) and loss factor (tan 1) variation with temperature. Complex aspects were elucidated in consecutive heating-cooling-heating cycles and by calculating the apparent activation energy of relaxations in multiplex experiments.
Polymer biocomposites based on segmented poly(ester urethane) and extracellular matrix components have been prepared for the development of tissue engineering applications with improved biological characteristics of the materials in contact with blood and tissues for long periods. Thermal, dynamical, and dielectrical analyses were employed to study the molecular dynamics of these materials and the influence of changing the physical network morphology and hydrogen bond interactions accompanied by phase transitions, interfacial effects, and polarization or conductivity. All phenomena that concur in the tested materials are evaluated by cross-examination of the dynamic mechanical characteristic properties (storage modulus, loss modulus, and loss factor) and dielectric properties (relative permittivity, relative loss factor, and loss tangent) as a function of temperature. Comparative aspects were elucidated by calculating the apparent activation energies of multiplex experiments.
In the present study, the antitumoral potential of three gel formulations loaded with carbon dots prepared from N-hydroxyphthalimide (CD-NHF) was examined and the influence of the gels on two types of skin melanoma cell lines and two types of breast cancer cell lines in 2D (cultured cells in normal plastic plates) and 3D (Matrigel) models was investigated. Antitumoral gels based on sodium alginate (AS), carboxymethyl cellulose (CMC), and the carbomer Ultrez 10 (CARB) loaded with CD-NHF were developed according to an adapted method reported by Hellerbach. Viscoelastic properties of CD-NHF-loaded gels were analyzed by rheological analysis. Also, for both CD-NHF and CD-NHF-loaded gels, the fluorescence properties were analyzed. Cell proliferation, apoptosis, and mitochondrial activity were analyzed according to basic methods used to evaluate modulatory activities of putative anticancer agents, which include reference cancer cell line culture assays in both classic 2D and 3D cultures. Using the rheological measurements, the mechanical properties of gel formulations were analyzed; all samples presented gel-like rheological characteristics. The presence of CD-NHF within the gels induces a slight decrease of the dynamic moduli, indicating a flexible gel structure. The fluorescence investigations showed that for the gel-loaded CD-NHF, the most intense emission peak was located at 370 nm (upon excitation at 330 nm). 3D cell cultures displayed visibly larger structure of tumor cells with less active phenotype appearance. The in vitro results for tested CD-NHF-loaded gel formulations revealed that the new composites are able to affect the number, size, and cellular organization of spheroids and impact individual tumor cell ability to proliferate and aggregate in spheroids.
A series of polyurethane/montmorillonite (PU/MMT) nanocomposites, based on poly(tetramethyleneglycol) (PTMG), α,ω-dihydroxylated poly(2-alkyl-2-oxazoline) (PROZO), [4,4’-methylenebis-(phenyl isocyanate)] (MDI) or [4,4’-methylenebis-(cyclohexyl isocyanate)] (H12MDI) and montmorillonite (MMT), were investigated. The amount of added clay ranged from 3 up to 10% by weight. The influence of the MMT weight fraction in the polymer matrix on the morphology and thermal, dynamic mechanical and tensile properties was characterized by scanning electron microscopy, X-ray diffraction analysis, Fourier-transform infrared spectrophotometry, differential scanning callorimetry, thermogravimetric analysis and dynamic—mechanical analysis. The results of the investigations were used to rank the nanocomposites according to their properties in relation to the polyurethane matrix structure and MMT content. It was evidenced that the silicate layers were preferentially, but not exclusively, attracted to the hydrophilic polar PROZO domains, their level of dispersion being controlled through specific intermolecular interactions and the filler loading amount. Introducing clay in the polyurethane matrix resulted in an increase of both tensile strength and thermal stability. Their non-monotonic dependence on clay content was explained by considering that concomitant and contrasting effects develop as the clay amount increases: an improvement of the filler—matrix interactions and a reduction of the matrix labile physical crosslinking degree by hydrogen bonding coupled with a lower dispersion homogeneity. For high inorganic filler amount aggregated clay particles together with regions with mixture of exfoliated and intercalated morphologies were revealed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.