Magnetic hydrogel nanocomposites offer a promising platform for magnetic hyperthermia by integrating magnetic nanoparticles (MNPs) within tunable polymer networks. However, the exact relationships between nanoparticle synthesis parameters, crystallite growth, and subsequent magnetothermal performance remain insufficiently understood. Herein, magnetic iron oxide nanoparticles were synthesized in situ within poly(N, N-dimethylacrylamide) (PDMAAm) hydrogels via alkaline coprecipitation. The independent effects of iron precursor concentration, external alkalinity, reaction temperature, and hydrogel network composition on nanoparticle loading, crystallite size, magnetic properties, and alternating magnetic field (AMF)-induced heating performance were systematically investigated. Increasing the iron precursor concentration enhanced nanoparticle loading while promoting crystal growth, yielding predominantly single-crystalline MNPs in the range of 9–12 nm. Efficient MNP formation required a strongly alkaline environment, whereas increasing the hydrogel crosslinking density restricted network swelling and iron-ion uptake, thereby limiting nanoparticle loading without substantially affecting the primary crystallite size. Notably, the reaction temperature strongly influenced crystallite growth and the resulting magnetothermal performance. Among the evaluated temperatures (room temperature, 30, 50, and 70 °C), an intermediate temperature of 50 °C produced an optimal crystallite size of approximately 11 nm, yielding the highest heating efficiency. Conversely, synthesis at 70 °C resulted in excessive crystallite growth and a subsequent decline in hyperthermia performance. These findings demonstrate that the magnetic heating response is governed predominantly by crystallite dimensions rather than MNP mass loading alone. Overall, this study establishes a direct synthesis–structure–property relationship, providing a rational framework for precisely tuning in situ generated MNPs in hydrogel matrices for advanced hyperthermia applications.
Foam gels (FGs) consisting of polymers, crosslinkers, and surfactants are widely investigated for mobility control and sweep efficiency improvement in chemical enhanced oil recovery (EOR). However, the coupled gelation–foaming mechanism and its structural evolution remains insufficiently understood. In this study, Raman spectroscopy was employed as the primary tool to track the gelation evolution of FG formulations consisting of xanthan gum (XG), chromium (III) chloride (CrCl3, XL), and alpha olefin sulfonate (AOS). Gelation behaviour was evaluated using Sydansk bottle tests and complemented by frequency sweep rheological analysis. Increasing the XL concentration enhanced crosslinking density and accelerated network formation, with 250 ppm XL provided a more balanced crosslinking process, resulting in the most stable gel structure. The incorporation of AOS accelerated gelation at 125 and 250 ppm but suppressed gel formation at 500 ppm. Rheological analysis showed that the storage modulus (G’) remained higher than the loss modulus (G”) throughout the investigated frequency range, confirming the formation of a stable viscoelastic gel network. Raman analysis revealed that gelation proceeds through an initial ionic conditioning stage followed by Cr³⁺-mediated coordination crosslinking with xanthan carboxylate groups. A transient red shift of the Cr–Cl stretching band ( 275 → 274 cm⁻¹) indicates ligand exchange during network formation. Simultaneously, the presence of AOS does not alter the fundamental coordination mechanism but primarily influences gelation kinetics. These findings indicate the composition influences to gelation behavior and structural evolution of FG confirmed by Raman spectroscopy, Sydansk codes, and rheology.
Hyaluronic acid (HA)-based injectable hydrogels are widely used in biomedical applications; however, systematic evaluations of molecular weight–dependent structure–property relationships under comparable crosslinking conditions remain limited. In this study, hydrogels were prepared by crosslinking HA with 1,4-butanediol diglycidyl ether (BDDE) using three different molecular weights ( 0.8, 1.5, and 2.5 million daltons (MDa)) and two crosslinker concentrations (0.9 and 1.3 wt
We investigated the curing behavior and thermo-mechanical properties of nanocomposite made from rubbery epoxy and graphene. The graphene platelets are modified with an ionic surfactant to solve the dispersion problem of graphene in epoxy resin. Temperature modulated differential scanning calorimetry (MDSC) was used to analyze the cure behavior of epoxy nanocomposites with varying contents of graphene. Isoconversion kinetics was studied using Friedman (differential) and Starink (integral) methods to determined activation energies for various nanocomposite formulations. The activation energy value initially decreases with increasing graphene content in the nanocomposite formulation and increases for higher concentrations. As evident from the Thermogravimetric Analysis (TGA) results the thermal stability of the nanocomposites is comparable to the pure epoxy network. Reinforcing effect of graphene has been demonstrated displaying about two fold increase in tensile strength due to the addition of 2.5 wt
In the present work, a bio-derived biopolymer electrolyte based on a neem gum–chitosan (70:30 wt.
