Developing biobased thermoplastic polyurethane (TPU) from renewable biomass resources is becoming urgent due to resource scarcity and environmental protection requirements. Herein, a chain extender diol (VAN-OH) containing dynamic imine bonds was synthesized using renewable biomass resource vanillin (VAN), then combined with 1,4-butanediol (BDO) in various proportions, and reacted with poly(caprolactone diol) and 4,4 '-diphenylmethane diisocyanate to synthesize degradable biobased TPU (BTPUs) with excellent performance. Fourier transform infrared, 1H NMR, X-ray diffraction, DMA, thermogravimetric analysis, molecular weight, chemical degradation, and mechanical tests systematically investigated the relationships between the polymer chain structure and the performance of BTPUs. The experimental results demonstrated that the high regularity and strong polar bonds (imine and ether) of VAN-OH enhanced the interactions between macromolecular chains and improved the hydrogen bonding combination, crystallinity, and phase separation of BTPUs, thereby exerting significant contributions to their thermomechanical and degradable properties. BVTPU1 with a mole ratio of BDO/VAN-OH = 7.5:2.5 exhibited the best mechanical performance, degradation time was 37.5% shorter, and initial pyrolysis temperature increased by 13.8% compared to BTPU0 without VAN-OH. In addition, BTPUs have shown some biodegradability and environmental friendliness in soil burial experiments under natural conditions.

Naphthalene is a fungicide that can also be a phase-change agent owing to its high crystallization enthalpy at about 80 degrees C. The relatively rapid evaporation of naphthalene as a fungicide and its shape instability after melting are problems solved in this work by its placement into a cured epoxy matrix. The work's research materials included diglycidyl ether of bisphenol A as an epoxy resin, 4,4 '-diaminodiphenyl sulfone as its hardener, and naphthalene as a phase-change agent or a fungicide. Their miscibility was investigated by laser interferometry, the rheological properties of their blends before and during the curing by rotational rheometry, the thermophysical features of the curing process and the resulting phase-change materials by differential scanning calorimetry, and the blends' morphologies by transmission optical and scanning electron microscopies. Naphthalene and epoxy resin were miscible when heated above 80 degrees C. This fact allowed obtaining highly concentrated mixtures containing up to 60% naphthalene by high-temperature homogeneous curing with 4,4 '-diaminodiphenyl sulfone. The initial solubility of naphthalene was only 19% in uncured epoxy resin but increased strongly upon heating, reducing the viscosity of the reaction mixture, delaying its gelation, and slowing cross-linking. At 20-40% mass fraction of naphthalene, it almost entirely retained its dissolved state after cross-linking as a metastable solution, causing plasticization of the cured epoxy polymer and lowering its glass transition temperature. At 60% naphthalene, about half dissolved within the cured polymer, while the other half formed coarse particles capable of crystallization and thermal energy storage. In summary, the resulting phase-change material stored 42.6 J/g of thermal energy within 62-90 degrees C and had a glass transition temperature of 46.4 degrees C at a maximum naphthalene mass fraction of 60% within the epoxy matrix.

Atmospheric black carbon (BC) is a major anthropogenic greenhouse agent, yet substantial uncertainties obstruct understanding its radiative forcing. Particularly debated is the extent of the absorption enhancement by internally compared to externally mixed BC, which critically depends on the interior morphology of the BC-containing particles. Here we suggest that a currently unaccounted morphology, optically very different from the customary core-shell and volume-mixing assumptions, likely occurs in aerosol particles undergoing liquid-liquid phase separation (LLPS). Using Raman spectroscopy on micrometer-sized droplets, we show that LLPS of an organic/inorganic model system drives redistribution of BC into the outer (organic) phase of the host particle. This results in an inverted core-shell structure, in which a transparent aqueous core is surrounded by a BC-containing absorbing shell. Based on Mie theory calculations, we estimate that such a redistribution can increase the absorption efficiency of internally mixed BC aerosols by up to 25% compared to the core-shell approximation.