ARTICLE IN PRESS
JID: JOBAB
[m3GeSsc;February 6, 2026;11:5]
Z. Wei, J. Liu, Y. Wang et al.
Journal of Bioresources and Bioproducts xxx (xxxx) xxx
with temperatures ranging from 13 to 34°C and relative humidity levels varying between 60% and 90%. Fruit weight was monitored at regular intervals to assess moisture loss and preservation efficacy.
2.7. Recyclability of PLS emulsion coated paper
The recyclability of PLS emulsion-coated paper was evaluated through a repulping process. Specifically, the P-PLS 2 was cut into approximately 2 cm × 2 cm pieces and subjected to hot water treatment at 100°C with continuous stirring to facilitate coating detachment. The pulp fibers were then filtered and collected, followed by the use of a fiber disintegrator to dissociate the fibers before paper formation. The recycled paper prepared from uncoated paper and from P-PLS 2 were designated as R-Uncoated and R-P-PLS 2 , respectively.
2.8. Assessment of biodegradability
The degradation experiment was conducted on the campus of Northeast Forestry University from April 20 to August 18, 2025. Polyethylene (PE) film, uncoated paper, and P-PLS 2 were cut into 5 cm × 5 cm samples and buried in soil. The samples were periodically taken out for photographic recording and weight measurement to assess their biodegradability.
3. Results and discussion
3.1. Characterization of LNPs
Alkali lignin, a natural polyphenolic polymer, exhibits extremely low solubility in aqueous media due to its highly cross-linked aromatic structure and hydrophobic characteristics. To enhance its applicability in water systems, the assembly of lignin into nanopar- ticles has emerged as an effective strategy. A solvent exchange-induced self-assembly approach was employed to fabricate LNPs. Initially, alkali lignin was dissolved in the DMSO to form a homogeneous solution. Subsequently, this solution was added dropwise into water, where the DMSO in the system was rapidly diluted with water, leading to a significant decrease in the solubility of lignin. During this process, the hydrophobic aromatic ring regions of the lignin molecules folded and aggregated to minimize contact with the aqueous phase, forming a hydrophobic core; meanwhile, the hydrophilic groups (e.g., hydroxyl and carboxyl groups) in the molecular structure oriented toward the aqueous phase, resulting in the formation of stable amphiphilic nanoparticles ( Fig. 2 a). This self-assembly process was driven by multiple intermolecular interactions, including van der Waals forces, hydrogen bonding, 𝜋 - 𝜋 stacking, and hydrophobic effects ( Moreno and Sipponen, 2024 ; Tao et al., 2024 ). The TEM images revealed that the obtained LNPs exhibited a spherical-like morphology, with diameters ranging from 8 to 35 nm and an average particle size of (20.8 ± 5.0) nm ( Figs. 2 b and 2 c). Notably, dynamic light scattering (DLS) measurements indicated a larger hydrodynamic size (67.37 nm) compared to TEM observations ( Fig. 2 d), which can be attributed to the swelling of LNPs in aqueous environments. Zeta potential analysis confirmed a strong negative surface charge ( − 37.6 mV) ( Fig. 2 e), primarily resulting from the ionization of phenolic hydroxyl and carboxyl groups in lignin. Colloidal systems with an absolute zeta potential greater than 30 mV are highly stable. When the absolute value of the zeta potential on the particle surface exceeds 30 mV, the electrostatic repulsion between particles is sufficient to over- come van der Waals attraction, thereby ensuring the kinetic stability of the colloidal system ( Vanderfleet and Cranston, 2021 ). The high negative zeta potential further demonstrates the excellent dispersion stability of LNPs in water.
3.2. Characterization of PLS emulsions
Stable O/W Pickering emulsions stabilized by LNPs were successfully developed, effectively achieving the synergistic composite and stable dispersion of water-soluble PVA and hydrophobic SA. In the binary PVA/SA system without LNPs, the absence of effective interfacial stabilizers prevented the formation of a stable emulsion, resulting in overall solidification during cooling due to the crystallization of SA. In contrast, after incorporating LNPs as emulsifiers, both the LNPs/SA and PVA/LNPs/SA systems formed uniformly stable emulsions, demonstrating the effective emulsifying capability of LNPs in complex multiphase systems (Fig. S2). As shown in Fig. 3 a, initially, PVA and LNPs were dissolved and dispersed, respectively, in the aqueous phase, while hydrophobic SA existed as a separate phase due to its immiscibility with water. Following high-speed homogenization, SA was dispersed into micrometer-sized droplets within the aqueous phase. At this stage, LNPs, owing to their significant amphiphilicity and high specific surface area, adsorbed onto the newly formed oil-water interface, partially embedding in the oil phase and partially remaining in the aqueous phase. Through irreversible interfacial adsorption and steric hindrance effects, LNPs effectively reduced the interfacial tension between oil and water, thereby stabilizing SA droplets ( Xu et al., 2024 ; Li et al., 2025 ). Meanwhile, PVA acted as a protective colloid. Driven by interfacial energy, the hydrophobic segments (residual acetoxy groups) of its molecular chains further adsorbed onto the surfaces of LNPs and extended into the uncovered regions of the oil-water interface, thereby enhancing the continuity and stability of the interfacial layer. In this composite interfacial structure, LNPs served as “bricks ” constructing the basic framework of the interfacial barrier, while PVA acted as the “cement, ” bridging, filling, and reinforcing the interface ( Nakamae et al., 1999 ; Kaewsaneha et al., 2022 ). The prepared PLS emulsions exhibited excellent long-term storage stability. After 30 d of static storage, no significant phase separation or stratification was observed in any of the samples, indicating superior physical stability ( Fig. 3 b). The SEM and CLSM images revealed that the particles in the emulsion were dispersed and exhibited a spherical-like morphology ( Figs. 3 c, 3 d, S3 and
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