Journal of Polymer Research最新文献

PA6T/66 and PA5T/56 with stable molecular weight and molecular weight distribution were prepared by one-step polymerization. The relationship between the structure and physicochemical properties of two kinds of polyamide samples was analyzed by software analysis and instrument test. The results show that the hydrogen bond between molecular chains has a significant effect on the properties of the materials. From the microscopic point of view, the mechanical properties of PA5T/56 molecular model were generally better than those of PA6T/66 molecular model because the hydrogen bond was not considered. At the macro level, the result was just the opposite because of the hydrogen bonds between the molecular chains. The Gibbs free energy of PA5T/56 dehydration condensation reaction was larger, indicating that the polymerization rate was faster, which was consistent with the actual situation. PA6T/66 belongs to the triclinic α crystal system, PA5T/56 belongs to the hexagonal γ crystal system, PA6T/66 T_g = 105.50℃, T_c = 257.34℃, T_m = 295.74℃, the ΔG_PA6T/66 and ΔG_PA5T/56 = 36.84 kJ/mol and 34.27 kJ/mol respectively indicate that the heat resistance and thermal properties of PA6T/66 were better than those of PA5T/56.

Polyvinyl chloride (PVC) is widely used as a commodity plastic in various industries and daily life. However, its green development is limited due to the fact that most plasticizers are either toxic or derived from food products. This study examines the plasticizing mechanisms by comparing three ricinoleic acid esters with different alkyl chain lengths to three commercial plasticizers, including dioctyl terephthalate (DOTP), epoxidized soybean oil (ESO), acetyl tri-n-butyl citrate (ATBC). The results indicate that ester bonds with higher polarity can readily penetrate PVC’s polar barrier and integrate into the polymer chain, while epoxy groups with lower polarity enhance chain stability. Moreover, benzene rings contribute to molecular stability and expand chain spacing. The length of the alkyl chain significantly influences the properties of structurally similar molecules: longer alkyl chains demonstrate greater resistance to migration and improved thermal stability, whereas shorter alkyl chains exhibit better plasticizing effects. Additionally, these ricinoleic acid plasticizers exhibit performance characteristics similar to those of commercial plasticizers in several aspects, underscoring the significant application potential of non-edible ricinoleic acid as a viable candidate to address the sustainability challenges of PVC materials.

Environmentally sustainable composites reinforced with sugarcane bagasse fiber (SBF), a natural fiber derived from the residual biomass of sugarcane processing, were developed using four polymer matrices: unsaturated polyester resin (UPR), bio-epoxy (BE), polylactic acid (PLA) and high-density polyethylene (HDPE). SBF content was varied at 3 wt%, 6 wt% and 9 wt%. Thermosetting composites were prepared using the open casting method, while thermoplastic composites were fabricated through compression molding. The study assessed physical and mechanical responses to elucidate the influence of matrix type and fiber loading. Composite density and properties like tensile modulus, flexural modulus, hardness and toughness improved with increasing fiber content, while tensile strength, elongation at break, flexural strength and flexural strain declined. Moisture susceptibility rose with higher fiber content, highlighting a trade-off between reinforcement and durability. Notably, 3 wt% BE composites exhibited superior tensile strength, 6 wt% BE had the highest tensile modulus and impact strength, 3 wt% PLA achieved peak flexural strength, 9 wt% PLA showed the greatest flexural modulus and 6 wt% PLA displayed the highest shore D hardness. These findings provide critical insights for optimizing polymer-fiber systems in sustainable composite design.

Bio-based healable polymer networks have attracted considerable attention because of their carbon neutrality and healability, which lead to long material life. In this study, mixtures of quercetin (QC), a 1/2 adduct (PO2PDI) of poly(trimethylene glycol) (PO3G) and 1,5-pentamethylene diisocyanate (PDI), and PDI trimer (PDIT) [QC (mol-OH):PO2PDI (mol-NCO):PDIT (mol-NCO) = 5(10 + α)/3:10:α] were thermally cured to produce fully bio-based polyurethane networks (BPUN-α, α = 0, 3, and 5), and the influence of the molar ratios of QC:PO2PDI:PDIT on the thermal, mechanical, and healing properties of the BPUNs were investigated. Differential scanning calorimetry revealed that BPUN-0 exhibited only one glass transition temperature (T_g), whereas BPUN-3 and BPUN-5 showed two T_gs ascribed to the glass transition of the PO2PDI/QC and QC/PDIT-rich components in consistent with the result of dynamic mechanical analysis. The tensile strength and modulus of BPUN-α increased with increasing α owing to the increasing crosslinking density. The decomposition test of the cured product of QC and PDI in excess 1-hexanol revealed that the dissociation of phenol-carbamate bonds started at approximately 100–120 ℃. The BPUNs were subjected to healing by pressing at 120 ℃ under 1 MPa for 1 h at least thrice; the healing efficiency in terms of tensile strength for the once-healed BPUNs was higher than 90%.

This study introduces a novel approach to enhance chitosan’s functional properties through grafting with tertiary butyl acrylate (chitosan-g-TBA) via free radical polymerization. The process utilized ceric ammonium nitrate as a redox initiator in an acidic medium, with optimal conditions identified as 2 g chitosan, 3.5 g tertiary butyl acrylate, 0.15 g ceric ammonium nitrate, and a reaction time of 240 min at 70 °C. The study’s significance lies in achieving a grafting efficiency of 98.9% and a grafting percentage of 131.9%, surpassing previously reported values for similar systems, while maintaining a low homopolymer content of 0.7%. Successful grafting and substantial structural modifications were confirmed through FTIR, TGA, GPC, SEM, and XRD analyses. FTIR spectra revealed the incorporation of ester functional groups, while TGA demonstrated improved thermal stability, with chitosan-g-TBA retaining 25.13% mass at 700 °C compared to 19.52% for unmodified chitosan. SEM imaging showed increased surface roughness and porosity, and XRD analysis indicated reduced crystallinity, further confirming successful grafting. Moreover, water swelling behavior decreased from 513.4% in unmodified chitosan to 245.6% in chitosan-g-TBA, highlighting its potential for applications requiring reduced hydrophilicity and enhanced thermal resistance. These results suggest that chitosan-g-TBA is a promising material for biomedical, environmental, and industrial applications, offering improved thermal stability and tailored hydrophilic-hydrophobic balance. This research provides a comprehensive understanding of optimizing graft copolymerization parameters and their impact on material properties.

The present work aims to study the impact of replacing HEMA monomer with a bio-based free radical hydroxyl functional macromonomer derived from castor oil (CO) in the synthesis of acrylic polyols. It also evaluates the coating properties of the resulting polyurethanes (PUs) in comparison to conventional acrylic polyols (AP-HEMA) derived from HEMA. To achieve this, castor oil was first reacted with maleic anhydride (MA) to produce the castor oil-derived free radical polymerizable hydroxyl functional macromonomer (COMA). Subsequently, castor oil-based acrylic hybrid polyols were synthesized using acrylate monomers, specifically methyl methacrylate (MMA) and butyl acrylate (BA), along with varying weight percentages of COMA through a conventional radical copolymerization process. The successful replacement of HEMA with COMA in the acrylic polymerization was verified through Fourier transform infrared (FTIR) spectroscopy, hydroxyl value analysis, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). The acrylic hybrid polyols derived from castor oil exhibited reduced viscosity, lower glass transition temperature (Tg), and decreased molecular weight compared to AP-HEMA. Both castor oil based, and AP-HEMA based acrylic polyols were further reacted with Isophorone diisocyanate (IPDI) at an OH: NCO ratio of 1:1.6 to form isocyanate-terminated polyurethane prepolymers. The Tg of the castor oil-based acrylic hybrid polyurethane coating films was found to be lower than that of petroleum-derived HEMA based acrylic polyols, demonstrating enhanced performance in terms of contact angle, water resistance, flexibility, adhesion, and abrasion resistance. The overall findings highlight the feasibility of using castor oil-derived COMA as a sustainable alternative in acrylic polyol formulations. The bio-derived free radical polymerizable hydroxyl functionality exhibits polymerization tendency within the conventional acrylic polymerization framework, indicating its potential as a substitute for the HEMA monomer in the synthesis of acrylic polyols, thereby yielding high solid content resins suitable for high-performance polyurethane coating applications.

A graft copolymer with thermoresponsive poly-2-isopropyl-2-oxazoline side chains and an aromatic polyester backbone containing aliphatic spacer –(CH₂)₄– was synthesized and studied using NMR, GPC, static and dynamic light scattering, and turbidimetry. The molar mass of the main and side chains, their length, as well as the number of side chains and the density of their grafting were determined. The conformation in aqueous solution was assessed. The behavior in water when heated over a wide range of concentrations and temperatures was studied. The phase separation temperatures and their dependence on concentration were obtained, and LCST = 50 °C was determined. Kinetic characteristics of equilibrium establishment in solution and the formation of supramolecular structures were analyzed. The influence of the spacer length and side chain length on the thermoresponsiveness and self-organization of copolymer macromolecules was discussed. It was shown that, due to the long side chains and short distance between grafting points, phase separation upon heating is preceded by intramolecular aggregation.

Visco-elastic properties in thermo-set composites can be enhanced using an Aramid matrix reinforced with multi-walled carbon nanotubes (MWCNTs). Surface modifications of MWCNTs, with silane coupling agents, improve their thermal and mechanical properties. The objective of this study is to evaluate Aramid-MWCNT nanocomposites modified with propyl silane (APrTES) and aromatic silane (APhTMS) by comparing their mechanical and thermal enhancements. Two types of composites were prepared: physically mixed with pristine MWCNTs (Ar-MWCNT) and chemically bonded with surface-modified MWCNTs (Ar-PrSi-MWCNT and Ar-PhSi-MWCNT). The mechanical and thermal stability of the composites was assessed using dynamic thermal mechanical analysis (DMTA) and thermogravimetric analysis (TGA). The chemically bonded Ar-PrSi-MWCNT composites demonstrated a 28% increase in tensile strength and a 15% improvement in storage modulus compared to the physically mixed composites. Glass transition temperature (Tg) increased by 10 °C, indicating enhanced thermal stability. The phenyl silane-modified composites (Ar-PhSi-MWCNT) exhibited the highest storage modulus (5.50 GPa) and Tg (370 °C), with a 28% increase in tensile strength. TGA results showed a decomposition temperature of 524 °C, confirming superior thermal stability. These improvements are attributed to the better dispersion of silanized MWCNTs and stronger interfacial bonding between MWCNTs and the Aramid matrix. The phenyl group in the silane modification contributes to a rigid interface, providing higher performance. Overall, surface modification with APrTES and APhTMS significantly enhances the thermal and mechanical properties of Aramid-MWCNT nanocomposites, with the phenyl silane-modified systems outperforming the propyl silane-modified and physically mixed systems.

The introduction of conjugated building blocks can improve the adsorption performance of hyper-crosslinked polymers (HCPs). Pyrene was introduced into the HCPs using chloromethylated polystyrene as the precursor, facilitating the hyper-crosslinking through a Friedel–Crafts reaction to finally synthesize an efficient adsorbent named CaHe-2. 1-Naphthylamine and 1-naphthol could be rapidly removed by CaHe-2 within 20 min with high removal efficiencies of 93.8% and 90.6%. The maximum adsorption capacity of CaHe-2 reached 171.71 mg g⁻¹ for 1-naphthylamine, exceeding most of previously reported adsorbents in, and 184.86 mg g⁻¹ for 1-naphthol, which is the maximum value reported so far. The removal efficiencies of CaHe-2 still remained > 98% after five cycles. This conjugation enhancement resulted in drastic changes in the 1-naphthylamine and 1-naphthol adsorption property of porous polymers, displaying a new strategy for creating HCPs with high adsorption capacities.

Graphical Abstract

In this research, we successfully synthesized an injectable, self-healing hydrogel based on succinyl chitosan (SC)/oxidized pectin (OP)/cellulose nanofibers (CNFs). This hydrogel was formed via the cooperative interaction of imine bonds, and hydrogen bonding, eliminating the necessity for a cross-linking agent. In all cases, the gelation occurred within seconds (< 60 s). The hydrogels demonstrated regeneration within a duration of 16 min, as determined by visual and rheological evaluations, without the need for any supplementary external stimuli. The elastic modulus of the SC/OP/CNF hydrogels was greater than that of the SC/OP hydrogel produced without CNF. Furthermore, SC/OP/CNF hydrogel showed excellent compatibility with blood (hemolysis rate < 3). Cytotoxicity studies, including MTT, and DAPI staining of hydrogels using human fibroblast cells (HFFF2) validated their good cytocompatibility. The results indicated that the prepared hydrogels could be used as injectable, self-healing hydrogel in biomedical contexts.