The solubility of 2′,4′-dihydroxyacetophenone (2′,4′-DHAP) in 10 monosolvents (methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, methyl acetate, ethyl acetate, propyl acetate, and benzene) and two binary solvents (ethanol + ethyl acetate and n-propanol + ethyl acetate) was determined using a gravimetric method at 101.3 kPa from 293.15 to 333.15 K. The experimental solubility was demonstrated to increase with the increasing temperature. The solubility of 2′,4′-DHAP is the highest in pure isopropanol, and the two binary solvents present a solubilizing effect on the solute. Furthermore, six thermodynamic models were employed to fit the solid–liquid equilibrium data, and the correlation results manifested that the modified Apelblat model had minimum ARD values of less than 1%. Finally, the KAT-LSER model was employed to analyze the solvent effect at 298.15 K. The results show that the contribution of the four interaction types α, β, π*, and δH account for 15.84%, 15.30%, 18.33%, and 50.53% of the total interaction force, respectively, and the solvent–solvent interaction represented by δH is the dominant factor affecting the solubility of 2′,4′-DHAP.

The solubility of trans-3-hydroxycinnamic acid in pure solvents (methanol, ethanol, n-propanol, isopropanol, nbutanol, isobutanol, methyl acetate, ethyl acetate, and n-propyl acetate) and (ethanol + ethyl acetate) cosolvent mixtures was measured by the gravimetric method from 293.15 to 333.15 K in normal pressure. The experimental results show that the solubility of 3-HCA(E) in alcohol solvents is greater than in ester solvents, which conforms to "like dissolves like". On this basis, the experimental result was correlated with semiempirical models (the modified Apelblat, van't Hoff, λh, Jouyban−Acree−van't Hoff equation, and combined model) and activity coefficient models (Wilson, NRTL, and UNIQUAC equation). The modified Apelblat model has the best correlation of the experimental data, with an ARD of less than 0.5% for pure solvents and cosolvent mixtures. The solvent effect was calculated by the KAT-LSER equation, showing that the hydrogen bond alkalinity of solvents−solutes (β) and the solvent self-association (δ H ) significantly influence the solubility of 3-HCA(E), accounting for 32.46 and 55.02%, respectively. Finally, the thermodynamic parameters (ΔH mix , ΔS mix , ΔG mix ,%ξ H , and %ξ TS ) were calculated. Negative values of both ΔH mix and ΔG mix indicate that the mixing process of 3-HCA(E) is exothermic and spontaneous. The Gibbs energy of the mixing process is jointly contributed by enthalpy and entropy.

Polymer welding has received numerous scientific attention, however, the welding of polymer nanocomposites (PNCs) has not been studied yet. In this work, via coarse-grained molecular dynamics simulation, the attention on investigating the welding interfacial structure, dynamics, and strength by constructing the upper and lower layers of PNCs, by varying the polymer-nanoparticle (NP) interaction strength 𝝐 NP-p is focused. Remarkably, at low 𝝐 NP-p , the NPs gradually migrate into the top and bottom surface layer perpendicular to the z direction during the adhesion process, while they are distributed in the middle region at high 𝝐 NP-p . Meanwhile, the dimension of polymer chains is found to exhibit a remarkable anisotropy evidenced by the root-mean-square radius of gyration in the xy-(R g,xy ) and z-(R g,z ) component. The welding interdiffusion depth increases the fastest at low 𝝐 NP-p , attributed to the high mobility of polymer chains and NPs. Lastly, although the mechanical properties of PNCs at high 𝝐 NP-p is the strongest because of the presence of the NPs in the bulk region, the welding efficiency is the greatest at low 𝝐 NP-p . Generally, this work provides a fundamental understanding of the interfacial welding of PNCs, in hopes of guiding to design and fabricate excellent self-healable PNCs.

The relationship between the chemical heterogeneity of two-dimensional (2D) filler surfaces and the mechanical properties of polymer nanocomposites (PNCs) is investigated using coarse-grained molecular dynamics simulations. It is found that there is an optimal surface heterogeneity that results in the highest tensile stress of the nanocomposite. The relationships between the heterogeneity and the entanglement of the polymer, the conformation of polymer chains, as well as the adsorption amount between the fillers and polymer chains are characterized. The results show that increasing the heterogeneity leads to a nonmonotonic variation in the adsorption amount, which further leads to a nonmonotonic variation in the entanglement between the polymer chains and the filler–polymer–filler bridging, and ultimately affects the tensile stress of the nanocomposites. Besides, the effects of the surface heterogeneity and the dispersion of the fillers on the surrounding chain adsorption capability are investigated, and it is found that these two factors affect the adsorption of the fillers on the polymers by changing the effect of entropy and enthalpy between the polymer chains and fillers together. Among them, the nonmonotonicity adsorption amount of the fillers to the polymers mainly comes from the variation of filler dispersion with the variation of heterogeneity. In general, this work provides a fundamental understanding of the reinforcement mechanism of polymer nanocomposites by 2D fillers, enlightening some rational principles for manipulating the physical properties of PNCs.