The development of high-performance polymer nanocomposites hinges on achieving full exfoliation of two-dimensional (2D) nanofillers and establishing strong interfacial interactions with the polymer matrix. This study presents a systematic approach to fabricating well-exfoliated poly(ethylene-co-vinyl acetate) (PEVAc)/zirconium phosphate (ZrP) nanocomposites with significantly enhanced oxygen barrier and mechanical properties. By combining pre-exfoliation, covalent surface functionalization, and solvent-assisted dispersion, the ZrP nanoplatelets were rendered hydrophobic and compatible with the PEVAc matrix, enabling stable dispersion and effective load transfer. The resulting nanocomposites exhibit remarkable improvements in gas barrier performance, melt strength, and tensile modulus without sacrificing processability or crystallinity.
ZrP was synthesized via a reflux method using zirconyl chloride and phosphoric acid, yielding platelets with an average lateral size of 100 nm and an interlayer spacing of 7.6 Å. Initial exfoliation was achieved by intercalating Jeffamine M1000 into the ZrP galleries, disrupting the hydrogen bonding network between adjacent layers. Subsequent grafting of 3-aminopropyltrimethoxysilane (APTMS) introduced free amine groups onto the ZrP surface, facilitating hydrogen bonding with the carbonyl groups in PEVAc. Finally, octadecyl trimethoxysilane (ODMS) replaced the residual M1000 at elevated temperatures, drastically increasing surface hydrophobicity. Thermogravimetric analysis confirmed a reduction in organic content from 35 mol% to 6 mol% after ODMS treatment, indicating successful surfactant exchange. Water contact angle measurements increased from 26° for pristine ZrP-M1000 to 82° for ZrP-AO, confirming enhanced hydrophobicity.
Solution mixing was performed using tetrahydrofuran (THF), which possesses hydrogen-bonding capability due to its ether oxygen. This solvent effectively stabilized the exfoliated state of ZrP-AO during dispersion by forming competing hydrogen bonds with both ZrP and PEVAc, preventing premature aggregation. Dynamic light scattering (DLS) showed that ZrP-AO maintained a hydrodynamic diameter of ~100 nm in THF even after adding PEVAc, indicating excellent colloidal stability.PMVK Antibody Purity Upon concentration and redilution, the system remained stable in THF but exhibited particle aggregation when diluted in non-hydrogen-bonding toluene—underscoring the critical role of solvent selection. Fourier-transform infrared spectroscopy revealed a clear shift in the carbonyl absorption peak, with a new shoulder at 1717 cm⁻¹, providing direct evidence of hydrogen bonding between the amine groups on ZrP and the ester groups in PEVAc.
Wide-angle X-ray diffraction (WAXS) and small-angle X-ray scattering (SAXS) analyses confirmed the absence of intercalated peaks in samples containing up to 5 wt% ZrP, indicating complete exfoliation. At 10 wt%, a weak SAXS peak at q = 0.158 Å⁻¹ corresponded to a d-spacing of 4 nm, suggesting partial stacking. Transmission electron microscopy (TEM) images clearly displayed uniformly dispersed, highly oriented ZrP nanoplatelets throughout the PEVAc matrix, with no visible aggregates or defects. These observations confirm that the surface modification and solvent engineering successfully prevented re-aggregation during processing.
Rheological measurements demonstrated substantial increases in complex viscosity and storage modulus with increasing ZrP content. At 3 wt% loading, the complex viscosity nearly doubled and the storage modulus increased by 2.5 times compared to neat PEVAc. The shear-thinning behavior intensified with higher filler content, reflecting enhanced chain entanglement and restricted mobility due to strong interfacial interactions. Dynamic mechanical analysis (DMA) revealed a significant rise in storage modulus above the glass transition temperature (Tg ≈ -20 °C), indicating that ZrP effectively constrained polymer chain motion in the rubbery state. The Young’s modulus of the nanocomposite increased by up to 250% at 10 wt% ZrP, while elongation at break decreased only slightly, preserving good ductility.CD81 Antibody manufacturer
Oxygen permeability tests conducted at 23 °C and 0% humidity showed dramatic reductions: 30% at 3 wt%, 50% at 5 wt%, and 65% at 10 wt% ZrP loading.PMID:35178114 These results align closely with the Gusev-Lusti model for 2D nanoplatelets, assuming random dispersion with preferred orientation parallel to the film surface and an effective aspect ratio of 100 nm. The excellent fit confirms that the ZrP is fully exfoliated, uniformly dispersed, and aligned, creating a highly tortuous path for oxygen molecules. No change in PEVAc crystallinity was observed, indicating that ZrP does not interfere with polymer crystallization, thus attributing all barrier enhancement solely to the nanoscale morphology.
In summary, this work demonstrates a powerful strategy for constructing high-performance PEVAc/ZrP nanocomposites through precise control of ZrP exfoliation, surface chemistry, and solvent compatibility. The synergistic effects of hydrogen bonding, improved hydrophobicity, and uniform dispersion lead to exceptional barrier and mechanical performance. The method is scalable, cost-effective, and applicable to other thermoplastic systems, offering promising potential for advanced applications in flexible packaging, protective coatings, energy-efficient insulation, and biomedical devices.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
