Journal of Polymer Research最新文献

In this research study, we describe the synthesis of new and tailored bio-composite materials by leveraging the synergistic interaction between polycaprolactone (PCL) and carboxymethyl hydroxypropyl guar gum (CMHPG). The proposed approach involves the in-situ ring opening polymerization (ROP) of ε-caprolactone, enabling the grafting of high molecular weight PCL chains (100 kg.mol⁻¹) onto CMHPG using a highly stable tin-based catalyst. The successful covalent association between the hydrophobic PCL chains and the hydrophilic CMHPG polysaccharide was confirmed. In addition, comprehensive structural (FTIR, DLS, contact angle and DRX), thermal (TGA and DSC), and mechanical characterizations were performed to investigate the synergistic effects between PCL and CMHPG. Notably, by precisely controlling the amount of CMHPG filler incorporated during synthesis, we achieved tailored performance in terms of film hydrophobicity and controlled biodegradability kinetics. These findings underscore the significant potential of the developed PCL bio-composites for specialized applications such as coatings, surface engineering, and the production of antifouling or repellent materials.

Graphical Abstract

A temperature, pH and ion sensitive, block copolymer, monomethoxypolyethylene glycol (MPEG)–block-polyethyleneimine (PEI) was synthesized by carbodiimide activation. MPEG-PEI block copolymer exhibited a thermally reversible phase transition from insoluble to soluble form with increasing temperature at neutral pH. MPEG-PEI chains are insoluble in the temperature range of 4–20 °C in an aqueous medium containing 3.5 mM phosphate ion. By increasing temperature, homogeneous and transparent solutions including dissolved copolymer are obtained at temperatures higher than 20 °C. The observed thermoresponsive behavior was opposite to that seen with poly(N-isopropylacrylamide). Depending on the phosphate ion concentration, the phase transition temperature for passing from insoluble to soluble form could be also precisely controlled between 4–40 °C. The reversible phase transition behavior of MPEG-PEI copolymer was confirmed by ten consecutive heating–cooling cycles between 4—50 °C. MPEG-PEI copolymer also exhibited another responsivity against pH. More appreciable increase in the average hydrodynamic size with the rising temperature was observed at pH 9.0 with respect to those obtained at pH 5 and 7. Temperature, pH and ion sensitive behavior of MPEG-PEI is documented for the first time. The reversible phase transition of MPEG-PEI is a promising tool which may open novel pathways, particularly for enzyme immobilization and drug release studies.

Nanostructured porous carbons, with its high specific surface area, rich pore structure, excellent conductivity and chemical stability, have become an excellent electrode material in advanced energy utilization technologies such as capacitive deionization and lithium–sulfur batteries. In this work, by controlling the concentration of oxidants and the addition of surfactants during the oxidative polymerization of pyrrole, the morphology and size of polypyrrole can be regulated. Nanostructured porous carbons with controllable morphology were successfully prepared by steam activation of polypyrrole particles and nanoribbons. In capacitive deionization experiment, the synthesized nanostructured carbon nanoribbon (NCNR) exhibits excellent electrochemical properties due to their rich pore structure and large surface area (1258 m² g^–1). In a 500 mg L^–1 NaCl solution, it has an electrosorption capacity of 12.9 mg g^–1 at 1.2 V. In addition, when NCNR is used as a host material for sulfur in lithium–sulfur batteries, it exhibits significantly improved discharge capacity and excellent cycling stability (maintaining a capacity of 672 mA h g^–1 after 200 cycles at a rate of 0.5 C), providing new ideas for solving the problems of capacity degradation faced by lithium–sulfur batteries.

Oriented polyvinylidene fluoride (PVDF) films were obtained in multistage process based on melt extrusion of polymer. We investigated the results of the polymorphic α→β crystalline phase transformation in the PVDF films subjected to uniaxial stretching. During uniaxial extension both appearance of a polar piezo active crystalline structure and significant changes in the samples morphology were observed. Variations in the PVDF films morphology, polymorphic composition, and supramolecular structure upon transformation were detected with Fourier transform infrared spectroscopy, wide-angle X-ray scattering, and scanning electron microscopy techniques. Broadband dielectric spectroscopy was used to ascertain a change in molecular mobility of the polymer chains during α→β phase transformation. The relaxation processes, γ-, α_а-, α_с-, and interfacial polarization, in both α- and β-phases of PVDF were identified in the dielectric loss spectra and described with either Arrhenius or Vogel-Fulcher-Tammann equations. The analysis of the equations parameters allowed concluding that initiation of a polymorphic α→β transition through uniaxial extension results in hindering the relaxators mobility in the β-phase of PVDF samples, except γ-relaxators. This finding confirms a proposal that γ-relaxators are located in the amorphous part of PVDF. Uniaxial extension resulted in a substantial increase in the interfacial polarization, which can be attributed to the emergence of new interface boundaries.

Graphical abstract

A higher resolution version of the Graphical abstract is available as Supplementary information

Flexible piezoelectric functional composite materials have the advantages of strong plasticity and good surface adhesion, and show great potential in smart wearable devices, electronic skin and other applications. However, due to the complexity of traditional preparation process, high molding cost and poor air permeability, its further development is limited. Direct ink writing (DIW) 3D printing technology is a rapid prototyping technology, with higher flexibility, faster manufacturing speed and lower manufacturing costs, is widely used in metal, ceramic and composite material molding. In this work, a ink system with polydimethylsiloxane (PDMS) as binder and barium titanate (BTO) ceramic powder as piezoelectric filler was developed, the printing work of flexible porous BTO/PDMS composite material was completed. DIW dual-nozzle printing technology was applied to realise “electrode-piezoelectric-electrode” integrated flexible porous functional gradient structure composites in this study. The results show that the BTO/PDMS ink has the characteristics of shear thinning. When the nozzle diameter is 0.5 mm, the printing speed is 650 mm/min, and the BTO mass fraction is 80%, the flexible porous piezoelectric composite with high precision and complex structure is printed. By phase analysis of BTO/PDMS, it is found that the sample has the characteristic peak of BTO. The microstructure analysis shows that the surface of the sample has good structural fidelity and there are a few island-like pores in the interior. The mechanical test shows that the maximum tensile strength of the sample is 1.33 MPa, the elastic modulus is 1.72 MPa, the longitudinal piezoelectric coefficient d₃₃ is 4.37 Pc/N, and the open circuit voltage VOC is 3.17 V. This work demonstrates an attractive method of moulding flexible piezoelectric materials with an “electrode-piezoelectric-electrode” structure, which provides a reference to current 3D printing flexible material fabrication techniques due to its simplicity of operation, time and manufacturing cost savings.

Poly(butylene adipate-L-lactide-butylene terephthalate) (PBLAT) was synthesized via a two-step method using terephthalic acid (PTA), adipic acid (AA), 1,4-butanediol (BDO), and L-lactide (L-LA) as polymerization monomers. The structure and properties of PBLAT affected by the content of L-LA were characterized by FTIR, 1 H-NMR, 13 C-NMR, GPC, XRD, DSC, and TG. The FTIR and NMR analyses confirmed that the structure of PBLAT conformed to the intended molecular design. GPC results showed that the number-average molecular weight ((stackrel{-}{{M}_{n}})) of PBLAT was between 13,026 and 23,246. The contact angle of all samples was less than 70°, demonstrating that the addition of L-LA enhanced the hydrophilicity of samples. DSC results showed that with an increase in L-LA content, the glass transition temperature (T_g) of PBLAT increased gradually, and the crystallinity initially increased before decreasing, which was consistent with the results of XRD. The highest 5% weight loss temperature of PBLAT was 343.0 °C, indicating that PBLAT has good thermal stability.

This study utilized Calamus tenuis fiber as reinforcement in fiber-reinforced polymer composites, focusing on the structural, crystalline, thermal, tensile, and morphological properties of Calamus tenuis fiber-reinforced epoxy composites (CTF/Epoxy composites). The composites were fabricated using the hand lay-up method, incorporating fiber weight fractions ranging from 0 wt% (neat epoxy) to 25 wt%, increasing in 5 wt% increments. FTIR spectroscopy identified the chemical compounds and functional groups, while XRD analysis confirmed that the crystalline structure of the composites remained unchanged with the addition of Calamus tenuis fibers. Thermogravimetric analysis (TGA) revealed that the 10 wt% CTF/Epoxy composite exhibited the highest thermal stability among the tested compositions. Differential Scanning Calorimetry (DSC) analysis indicated an increased glass transition temperature (T_g) in the 10 wt% CTF/Epoxy composite, further confirming improved thermal stability. Notably, the 10 wt% fiber content led to significant improvements in tensile properties, with tensile strength increasing from 17.5 ± 1.42 MPa to 21.08 ± 1.03 MPa, and Young’s modulus rising from 2.53 ± 0.12 GPa to 2.84 ± 0.09 GPa. Scanning Electron Microscopy (SEM) demonstrated enhanced fiber-epoxy bonding, while Atomic Force Microscopy (AFM) indicated increased roughness with higher fiber loadings. Overall, the 10 wt% CTF/Epoxy composite shows substantial potential for structural and infrastructure applications.

In developing flexible type advanced electrical and electronic devices, rationally designed excellent performance polymer dielectrics are highly admired in technological industries. To contribute in this field, herein, the entire composition ratios polymer blend (PB) films of poly(vinylidenefluoride-co-hexafluoropropylene) (P(VDF-HFP)) and poly(methyl methacrylate) (PMMA) are prepared following the solution-cast procedure. The prepared PB films are designated as xP(VDF-HFP)/(100-x)PMMA, where x is varied, in steps, as 100, 80, 50, 20, and 00 wt%. The optical, thermal, structural, and broadband dielectric and electrical properties of these PB films are characterized in detail employing advanced instruments and interpreted meaningfully with blend compositions. The ultraviolet–visible (UV–Vis) spectroscopic results confirmed predominantly composition tunable UV absorbance as well as energy bandgap values of these PB films, which decreased when the P(VDF-HFP) amount was relatively reduced. Differential scanning calorimetry (DSC) measurements explained the reduction in the degree of crystallinity and crystallite thermal stability on decreasing the P(VDF-HFP) amount in the blend and also their transformation to amorphous type miscible blend for the compositions having PMMA amount exceeding 60 wt%. The Fourier transform infrared (FTIR) spectra also elucidated the formation of miscible blends for PMMA-rich compositions owing to a large increase in heterogeneous hydrogen bonding. The broadband dielectric spectroscopic measurements over the nine decades of harmonic electric field frequency (20 Hz to 1 GHz range) unveiled the contribution of various polarization processes and their alteration with frequencies that govern the dielectric permittivity and its dispersion, and different relaxations related to the structural dynamics of the blended polymers. The outcome provides a facile strategy to realize the composition reliant dielectric and optical properties of P(VDF-HFP)/PMMA blend films and helps in proposing their feasible applications as innovative optical and dielectric materials for flexible technologies.

In the present work, a novel pyrazine based chitosan material was synthesized by functionalizing chitosan with chloroacetyl chloride and further modification with ethylene 1,2 diamine, thus a polymer matrix is obtained. Further the adsorbent material was characterized and verified using analytical techniques such as XRD, SEM, FTIR and TGA. The adsorbent material was analyzed for the adsorptive take-up process with a initial dye concentration varying from 20–100 mgL⁻¹ and the adsorptive process occurred due to the electrostatic interaction between the nitrogen atom of chitosan and the methyl orange dye molecule. The equilibrium adsorptive capacity obtained for the synthesized adsorbent material was 45.45 mg g⁻¹. The adsorptive mechanism predicted the electrostatic interaction between the two atoms and the increased in the adsorption efficiency is contributed by the increased number of hetero atoms in the chitosan structure and the adsorption kinetics was found to be pseudo-second-order kinetics and with a monolayer coverage process indicating the Langmuir adsorption isothermal fit. Further, the evaluated thermodynamic parameters showed the adsorption process to be non-spontaneous and endothermic in nature. A regeneration and reusability study was achieved for the composite material using convenient stripping solutions and the adsorbent was successfully regenerated.