Lignin nanoparticle-enhanced PVA foils for UVB/UVC protection

In this study, we report on extracting lignin from Duabanga grandiflora (Khukon), an untapped wood source, and its transformation into nano-lignin (NL) to create durable and thermally stable composites. Utilizing ultrasonication, we synthesized spherical lignin nanoparticles with an average size of 8 nm, as verified by high-resolution transmission electron microscopy. These nanoparticles were integrated into a polyvinyl alcohol (PVA) and guar gum (GG) matrix, resulting in PVA-GG-NL (PGNL) composites. PVA-GG nanocomposite films containing various contents of lignin nano-particles (1, 2 and 3 wt%) were formulated by a simple solvent cast method and cross-linked by adding borax. Addition of 1 wt% lignin nanoparticles brought in the composite films with 29.8 MPa tensile strength and 139.3% elongation at break. Compared to PVA-GG-lignin composites, the PGNL composites exhibited a 59.4% increase in tensile strength and enhanced elongation at break and good thermal degradation properties. Notably, the PGNL composite films were transparent but could shield 99.9% of the UV-A (320–400 nm) and UV-B (280–320 nm) radiations, marking a significant advancement in UV protective materials. Our innovative use of D. grandiflora-derived NL in a dual-polymer network not only underscores the potential of renewable resources in high-performance applications but also aligns with the principles of a circular bioeconomy by offering a sustainable solution for effective UV protection.

Sonochemical synthesis of lignin nanoparticles and their applications in poly (vinyl) alcohol composites

New insights into greener skin healthcare protection: Lignin nanoparticles as additives to develop natural-based sunscreens with high UV protection

Highly transparent PVA/nanolignin composite films with excellent UV shielding, antibacterial and antioxidant performance

Strong, UV-blocking, and hydrophobic PVA composite films containing tunable lignin nanoparticles

Development of composite film based on polyvinyl alcohol with binary nanoreinforcements for active packaging of fresh-cut apples

Thermal, antioxidant and swelling behaviour of transparent polyvinyl (alcohol) films in presence of hydrophobic citric acid-modified lignin nanoparticles.

A dual approach with lignin and nanolignin: Reinforcing UV stability and sustainability in PVA matrices.

Modification of walnut shell lignin nanoparticles through deep eutectic solvent for application in active food packaging films.

In this research, titanium dioxide (TiO2) nanoparticles were immobilized into polyvinyl alcohol (PVA) matrix without and with surfactants via solution casting film combined with thermal treatment method. The dispersion and distribution of TiO2 nanoparticles presented by scanning electron microscopy (SEM) showed the uniform distribution of TiO2 nanoparticles in PVA matrix with surfactant. Fourier-transform infrared spectroscopy (FTIR) showed increasing intensity peak at 560-800 cm-1 corresponding to Ti-O stretching vibration indicating interaction between PVA and TiO2 after thermal treatment. X-ray diffraction (XRD) result showed peak of PVA crystal structure due to the thermal treatment, and the addition of surfactant could decrease the average crystallite size of TiO2 in PVA/TiO2 nanocomposite films. Photocatalytic activity was determined from the film efficiency on removal of methylene blue (MB) under ultraviolet (UV). The results showed the greater MB removal efficiency of the PVA/TiO2 nanocomposite films with surfactant and thermal treatment than those without surfactant and thermal treatment.

Tailoring kraft lignin for high-performance nanoparticles: from structure to function.

PurposeThis study aims to fabricate multiwalled carbon nanotubes (MWCNTs)-mediated polyvinyl alcohol (PVA) composite films using the solution casting approach.Design/methodology/approachThe prepared films were evaluated for diverse structural, surface, optical and electrical attributes using advanced analytical techniques, i.e. electron microscopy for surface morphology, Fourier transform infrared spectroscopy for tracing chemical functionalities, x-ray diffraction (XRD) for crystal patterns, water contact angle (WCA) analysis for surface wettability and UV visible spectroscopy for optical absorption parameters. The specimens were also investigated for certain rheological, mechanical and electrical properties, where applicable.FindingsThe surface morphology results expressed a better dispersion of MWCNTs in the resultant PVA-based nanocomposite film. The XRD analysis exhibited that the nanocomposite film was crystalline. The surface wettability analysis indicated that with the inclusion of MWCNTs, the WCA of the resultant nanocomposite film improved to 89.4° from 44° with the pristine PVA film. The MWCNTs (1.00%, w/w) incorporated PVA-based film exhibited a tensile strength of 54.0 MPa as compared to that of native PVA as 25.3 MPa film. There observed a decreased bandgap (from 5.25 to 5.14 eV) on incorporating the MWCNTs in the PVA-based nanocomposite film.Practical implicationsThe MWCNTs’ inclusion in the PVA matrix could enhance the AC conductivity of the resultant nanocomposite film. The prepared nanocomposite film might be useful in designing certain optoelectronic devices.Originality/valueThe results demonstrated the successful MWCNTs mediation in the PVA-based composite films expressed good intercalation of the precursors; this resulted in decreased bandgap, usually, desirable for optoelectronic applications.

Lignin nanoparticles (LNPs) are usually produced from lignin solution through supersaturation. The structure of the lignin in solution is still poorly understood due to structural variability of isolated lignins. Here, lignins were extracted from different plants to establish a general pattern of their structure in several lignin solvents. Lignin molecules (lignin subunits) and larger aggregates were observed in dimethyl sulfoxide (DMSO), ethylene glycol (EG) and 0.1 N NaOD solutions by small-angle neutron scattering (SANS). It was proposed that the aggregates were composed of lignin subunits with a higher molecular weight and a higher ratio of the aliphatic to phenolic hydroxyl groups. The size, shape, and compactness are important factors that affect the uses of the LNPs, which were obtained from the SANS data for the first time. A discrepancy in the radius between SANS and DLS was discovered, pointing to a large hydration shell around the LNPs in aqueous solutions. The cytotoxicity of the corncob lignin, kraft lignin, and their LNPs were measured and compared.

Lignin nanoparticle reinforced multifunctional polyvinyl alcohol/polyurethane composite hydrogel with excellent mechanical, UV-blocking, rheological and thermal properties

Preparation and characterization of lignin nanoparticles and chitin nanofibers reinforced PVA films with UV shielding properties