Colloid and Polymer Science最新文献

In order to overcome the drawback of poor mechanical and rheological properties and potentially extend the poly(butylene adipate-co-butylene terephthalate) (PBAT) application market, in this work, we developed PBAT blend with excellent comprehensive performance through blending with biodegradable poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA). Two-step melt blending and constant polylactide (PLA) content were devised to prepared PBAT blend. The effect of PDLA on the crystallization properties, rheological properties, miscibility, morphological structure, and mechanical properties of blend was investigated. According to torque-time curve and DSC results, PLA stereocomplex (SC-PLA) crystallites were formed in blend system. DMA results confirmed that the compatibility between PBAT and PLLA was not changed when PDLA was introduced. SEM results showed that the phase morphology of PBAT/20PLLA/0PDLA blend displayed typical sea-island structure and the particle size of dispersed phase decreased accompanying by agglomeration when PDLA was added. Rheological results showed that percolation SC-PLA network structure had formed and a much denser crystallite network could be formed with high PDLA content, which significantly enhanced rheological properties of blend. The mechanical results demonstrated that the addition of PDLA could significantly enhance mechanical properties. The blend with 6 wt% PDLA presented yield strength, elongation at break, and modulus about 13.3 MPa, 307%, and 221.2 MPa, respectively, the yield strength and modulus increased by 141.7% and 54.7% compared with the pure PBAT.

Graphical abstract

Considering the carcinogenic and mutagenic properties of azo anionic dyes on the environment and human health, the development of efficient adsorbents for the removal of these water pollutants is very important. Therefore, the main aim of this research is to develop cost-effective and efficient melamine-formaldehyde (MF) microspheres for the removal of anionic dyes from wastewater. MF nanocomposite (MF-NGQD) microspheres were prepared using varying amounts of N-doped graphene quantum dots (NGQDs) through a simple polycondensation method. According to the SEM images, the MF-NGQD microspheres contain up to 10 wt% monodisperse, with an average diameter of 427 nm, which is smaller than the MF microspheres with a diameter of ⁓2.1 μm. The measurement of zeta potential (ZP) as a function of solution pH showed that the amount of ZP is significantly affected not only by the pH of the solution but also by the content of NGQDs in the microspheres. BET results revealed higher surface area and larger pore volume of nanocomposite microspheres (11.40 m² g⁻¹ and 0.030 cm³ g⁻¹) compared to MF microspheres (5.40 cm³ g⁻¹ and 0.017 cm³ g⁻¹). Batch adsorption experiments were carried out to investigate the adsorption properties of microspheres on Congo Red (CR). The results indicated that MF-NGQD microspheres with an amount of 0.05 g/25 mL were able to remove CR up to 97% at pH 6.0 with C₀ of 50 mg L⁻¹ in 45 min with an adsorption capacity of 91.74 mg g⁻¹. Adsorption processes were further analyzed through isotherm and kinetic studies, which showed a better fit with the Freundlich model and pseudo-second-order model, respectively. In conclusion, our finding demonstrates that MF-NGQD-10 microspheres are highly effective adsorbents for the removal of anionic dyes such as Congo Red from textile effluents, offering a promising solution for wastewater treatment. Future studies should explore the scalability and real-world application of these microspheres.

Graphical abstract

Polyvinyl alcohol (PVA) and chitosan (CS) were mixed with purple tomato anthocyanins (PTA), and then nano zinc oxide (nano-ZnO) or calcium chloride (CaCl₂) were added to prepare PVA/CS/PTA/ nano-ZnO (PCP-ZnO) or PVA/CS/PTA/CaCl₂ (PCP-CaCl₂) films. The effects of nano-ZnO and CaCl₂ on the morphology, pH response, color stability, color reversibility, antibacterial activity, antioxidant activity, mechanical properties, water vapor permeability and UV absorption characteristics of films were studied. In addition, its application in intelligent packaging to monitor the freshness of pork was also studied. It was found that both nano-ZnO and CaCl₂ can reduce the transmittance of the film in the visible light region, and the film with addition of nano-ZnO was more sensitive to pH. During the 14 day storage period, the film modified with CaCl₂ exhibited better color stability. SEM images indicate that the addition of nano-ZnO or CaCl₂ alters the microstructure of the film. The mechanical, antibacterial and antioxidant properties and also the application as freshness indicator of PCP-CaCl₂ film were superior to those of PCP-ZnO film. Those indicated that the prepared PCP-CaCl₂ film is a potential candidate for active and intelligent packaging applications.

Graphical abstract

This study describes the development of ulvan films blended with selected concentrations of carnauba (Copernicia prunifera) wax (0%, 5%, 10% and 15% w/w) to modify its hydrophilic nature. The effects of carnauba wax on the physical, chemical, and mechanical properties of the films were studied. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectrum evidenced the presence of uronic acid carboxyl groups, ester sulfate groups, and the vibrational modes associated with C-O groups in the glycosidic linkage between rhamnose and glucuronic acid, which constitute the characteristic ulvan bands. Higher wax concentrations led to lower intensity of transmission peaks in the range of 3500 cm^-1 to 3200 cm^-1, indicating an increase in the films' hydrophobicity. This enhanced hydrophobicity is further supported by contact angle measurements, where the wax-free film (CC0) exhibited a contact angle of 51.85 ± 1.61° (hydrophilic), while the film with 15% wax (CC15) showed a contact angle of 66.64 ± 2.15° (hydrophobic). Additionally, a maximum reduction in the solubility of films with 10% carnauba wax compared to wax-free films. Meanwhile, both tensile strength and elongation at break show negligible changes regardless of carnauba wax presence. The findings indicate that carnauba wax-enriched ulvan films enhance hydrophobicity without compromising mechanical integrity, highlighting its potential for use in food packaging applications.

Graphical Abstract

The study of steady natural convection Couette flow is vital in designing as well as the optimization of microfluidic devices, geothermal energy systems, cooling of electronic devices and systems, etc., due to several recent applications. The present investigation aims to analyze radiative heat transfer and dissipative energy in the free convection of Couette flow within a vertically positioned channel. Incorporating carbon nanotubes (CNTs), specifically single-wall carbon nanotubes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs), into the base fluid water enhances the flow phenomena. Additionally, the explanation of heat source/sink on the energy phenomenon encounters various properties. Further, suitable similarity variables are employed for the transformation of the governing equations. However, the homotopy perturbation method (HPM), an analytical approach, is used for the solution of the coupled ordinary differential equations. The thermophysical parameters and their impact are depicted through graphs, and the comparative analysis is presented via tables.

Graphical Abstract

• Explore the combined effects of CNT nanoparticle concentrations on the Couette flow through a vertical channel.

• The inclusion of radiating heat on free convection of nanofluid enriches the flow phenomena.

• The adaptation of various thermophysical properties, i.e., in particular, the thermal conductivity, shows its effectiveness on the heat transport phenomenon.

• Clarify different contributing parameters by using the homotopy analysis method.

The objective of this study was to enhance the anticancer potential of curcumin (CR)-loaded niosomal formulation against human myeloid leukemia cell lines and its antioxidant activity by the incorporation of amphiphilic palmitoyl-modified arginine (PL-ARG) serving as a positively charged amphiphile. PL-ARG was synthesized by using palmitoyl chloride (PL) and l-arginine (ARG) followed by characterization through ESI–MS, ¹H-NMR, and FT-IR. The proportion of niosomal constituents including Tween 80/20 and cholesterol was optimized using experimental design to achieve small size vesicle with enhanced encapsulation of CR, and the optimized proportion was then used for the development of niosomal formulation functionalized with synthesized PL-ARG (PL-ARG-CR-NSMs). For the comparison, non-functionalized CR-loaded niosomes (CR-NSMs) were also prepared. The developed niosomal vesicles were characterized for encapsulation efficiency, size, PDI, zeta potential and surface morphology, and in vitro drug release. CR was encapsulated in niosomes with entrapment efficiency of 78.94 ± 5.16% (PL-ARG-CR-NSMs) and 65.82 ± 3.52% (CR-NSM) and provided a sustained drug release profile. Interestingly, when compared to CR-NSMs, the PL-ARG-CR-NSMs demonstrated enhanced growth inhibition of human myeloid leukemia cell lines supporting the antitumor efficacy of CR delivered from PL-ARG-CR-NSMs against human myeloid leukemia cell lines as well as the feasibility of arginine modified niosomes as a sustainable cancer treatment approach.

Graphical Abstract

The study investigates the heat and mass transfer of mixed peristaltic Casson fluid flow through a porous medium in the presence of electroosmosis. It uses the lubrication LWL-LRN analytical technique to transform flow-control equations into ordinary differential equations. The equation is simplified using a numerical solver, bvp4c, in MATLAB software. The study analyses the behaviour of momentum, thermal, solutal, and nanoparticle concentration using parameters such as the magnetic field parameter, porous, electroosmotic, Prandtl, thermal Grashof number, and solutal concentration. Comparing this work with the existing investigation reveals a high level of concordance regarding the impact of thermophoresis and Brownian variables on momentum fields. The study’s novelty is the double-diffusive effects of Casson fluid, which provides a more accurate characterisation of its flow behaviour with convective boundary conditions over an inclined surface. Such observations are useful in real-life applications to capture the shear and stress-thinning properties and flow of synovial fluid in joints, as well as to understand blood flow in several physiological conditions.

Graphical Abstract

The emergency of peptide-assembled nanomaterials motivates the efforts towards understanding the composition effects governing the assembly structure of peptides. Herein, we used time-lapse atomic force microscopy (AFM) to characterize the time-dependent structural transformation of phenylalanine (F)-rich self-assembled peptides and elucidated the impacts of composition heterogeneity on modulating peptide aggregation. Four binary peptides (F5Y5, F5A5, F5H5, and F5D5) were synthesized to arrange distinct types of amino acids, including aromatic tyrosine (Y), nonpolar alanine (A), cationic histidine (H), and anionic aspartic acid (D), in the proximity of an F-rich moiety. We compared the time-dependent structural transitions of these peptide assemblies using AFM. F5Y5 and F5A5 were observed to form fibril-like aggregates over time, whereas F5H5 and F5D5 assembled into globular particles during the time course examined. The impacts of neighboring amino acids on affecting F-rich peptide fibrillation are in line with the hydrophobicity scales of amino acid side chains. Specifically, Y and A facilitate the fibril aggregation, whereas H and D hinder the fibril formation of F-rich peptides. Our results manifest the hydrophobicity of amino acids proximal to the F residues is important for the fibril-like aggregation of peptides.

Graphical abstract