Macromolecular Chemistry and Physics最新文献

The incorporation of nanofillers into biodegradable polymers is an effective approach to improve the physical properties and mechanical performance for various practical applications. In particular, the interfacial microstructure between the polymer and nanofillers plays a critical role in determining the macroscopic properties of the resulting polymer nanocomposite. In this work, we report carbon nanotube (CNT) induced interfacial transcrystallization of poly(L-lactic acid) (PLLA) in the single-fiber composite. The dynamic process of PLLA transcrystallization around the single CNT fiber is investigated under isothermal crystallization in the temperature range from 124°C to 136°C using in situ polarized optical microscopy. Transcrystallization kinetics are analyzed based on polymer heterogeneous nucleation and crystallization theories. The interfacial free energy difference parameter (Δσ/σ = 0.057) and the fold surface free energy (σ_e = 5.82 × 10⁻² J/m²) are calculated to assess the nucleation ability and crystallization barrier, respectively. Atomic force microscope (AFM) analysis reveals radially aligned edge-on lamellar crystals adjacent to the CNT fiber. Alternative transformation from the edge-on lamellar orientation to a flat-on orientation results in a banded transcrystalline texture. A proposed mechanism is presented that lamellar twisting during the crystal growth is attributed to the banded transcrystals.

This study presents a one-pot emulsion polymerization that combines step-growth process of methylene-bis(4-cyclohexylisocyanate) (HMDI) and polyether polyol (EP-330N) to form polyurethane (PU) and chain growth radical polymerization of methyl methacrylate (MMA) and crosslinker ethylene dimethacrylate (EDMA) to produce crosslinked poly(methyl methacrylate) (PMMA). The as-prepared interpenetrating PU-PMMA hybrid latexes have features of tailored cross-linking densities (gel content as high as 49.8%, controlled by the molar ratio of ─NCO/─OH, namely R-value), yielding colloidally stable particles (90–110 nm) with a spherical morphology. FTIR and Soxhlet extraction are employed to characterize the successful synthesis of hybrid particles. As-proof of application, the PU-PMMA particles have been used as a toughening modifier of poly(vinyl chloride) resin (PVC). The impact strength of PVC blends increases from 2.6 to 4.6 kJ/m² with 0–10 phr PU-PMMA addition. These results demonstrate that the one-pot emulsion polymerization integrating radical and step-growth mechanisms could be considered as a straightforward, green emulsification method to synthesize interpenetrating hybrid particles with tunable properties.

Lignin, an underutilized aromatic biopolymer from agricultural waste, is promising for functional hydrogels. However, the complex composition, molecular heterogeneity, and low active site accessibility of lignin severely restrict its practical applications. Traditional lignin extraction methods result in over 80% cleavage of β-O-4 bonds and a significant loss of phenolic hydroxyl groups. In this study, four different molecular weight lignins (F1-F4) were obtained from cotton stalks via γ-valerolactone pretreatment. The molecular weights of F1-F4 were 5203, 2926, 1956, and 938g/mol, with total phenolic hydroxyl contents of 0.03, 0.09, 0.27, and 0.54 mmol/g, respectively. Compared with hydrogels of the high-molecular-weight lignin (F1), the low-molecular-weight lignin-based hydrogel (F4) exhibited 3.32-fold enhanced elasticity, 4.23-fold improved conductivity, and 1.52-fold higher antibacterial activity. Notably, the γ-valerolactone pretreatment preserved β-O-4 bonds more effectively, while increasing the pore size by 1.57-fold. These results indicated that the low-molecular-weight lignin with high phenolic hydroxyl content conferred the hydrogel with significantly enhanced elasticity, conductivity, and antibacterial activity, making it highly promising for applications in drug delivery, wound healing, and wearable biosensors. This work demonstrates a green route to valorize agricultural lignin into high-performance hydrogel materials.

The synthesis of crystalline hyper-crosslinked polymer still challenges scientists due to the irreversible, random nature of the Friedel–Crafts reaction. In this work, we report a series of crystalline TPA-CC-x combined by 1, 3, 5, 7-tetraphenyladamantane (TPA) and cyanuric Chloride (CC) based on Friedel–Crafts reaction. The X-ray diffraction (XRD) analysis confirmed the crystal structure of these polymers. The porosity and pore size distribution analysis discovered that the spec, while the TPA-CC-x were almost entirely composed of micropores with the pore diameter approximately located at 1.223 nm. Combining the advantages of abundant adsorption sites, electronegative natures, and porous structures, TPA-CC–1 exhibits ultrahigh adsorption capacities and adsorption rates toward cationic dyes, including malachite green (MG) and Rhodamine B (RhB). Notably, the maximum adsorption capacity of TPA-CC–1 toward RhB is 2089.3 ± 55.3 mg g⁻¹, which exceeded all previously reported porous manuscript organic polymers adsorbents. The contribution represents the first report of crystalline HCPs that not only expand their structural diversity but also exhibit excellent adsorption properties.

In this study, a series of cross-linked poly(glycerol sebacate itaconic) (PGSIA) was prepared using a two-step method, involving pre-PGS oligomers with varying hydroxyl contents and molecular weights. The effects of different pre-PGS oligomers on the structure and properties of the cross-linked PGSIAs were investigated. Upon increasing the pre-PGS molecular weight, the degree of cross-linking degree of the PGSIA increased accordingly. Young's modulus and tensile strength increased dramatically from 1.97 and 1.25 MPa to 24.94 and 7.82 MPa, respectively. Meanwhile, the glass transition temperature (T_g) increased from −15.5°C to −5.3°C. The water contact angle increased from 62.3° to 88.0°, and the degradation mass loss decreased from 12.8% to 4.3%. Upon increasing the hydroxyl content, the degree of cross-linking degree increased, along with the increase in the Young's modulus, which increased from 3.17 to 9.97 MPa, while tensile strength increased from 1.35 to 3.39 MPa. The T_g decreased gradually from −7.5°C to −19.8°C. The water contact angle increased from 47.9° to 80.4°, and the loss of degradation mass loss increased from 6.1% to 23.5%. In this work, poly(glycerol sebacate itaconic) (PGSIA), was prepared by a solvent-free melt process as a green chemistry advantage.