Journal of Polymer Science最新文献

The wide applications of continuous silicon carbide fiber (SiC_f) are constrained by the high cost of its common raw material, polycarbosilane (PCS). Polymethylsilane(PMS) exhibits higher reactivity and a lower production cost than PCS. Nevertheless, the disadvantages of pyrophoric nature and thermoset properties in raw PMS necessitate improvements for practical applications. Herein, benzoxazine resin (VBR) with vinyl functional groups is utilized to modify PMS via hydrosilylation. After modification, a stable preceramic polymer with excellent processability is obtained. The ordered and symmetrical molecular architecture of the initial PMS is changed. This results in an increase of the molecular rigidity, which in turn constrains the alteration of molecular conformation and diminishes the tendency toward crystallization. The modified PMS exhibits a shear-thinning behavior and thermoplastic properties upon heating, making it suitable for melt-spinning. The molecular orientation of the newly formed network structure in the modified PMS is aligned with the shear force during melt-spinning, facilitating the extrusion of green fibers and thereby imparting superior spinnability to the modified PMS. By optimizing the temperature of melt-spinning to 210°C, we produce continuous SiC green fibers with lengths exceeding 10 km. This work presents a promising candidate for the economic preparation of SiC fiber.

Dynamically crosslinked polymer networks, characterized by non-permanent bonds, offer unique viscoelastic properties that can be used for various applications such as self-healing coatings and reusable adhesives. This study investigates the spreading behavior of a silicone polymer network with dynamic imine bonds, focusing on the relationship between material properties and spreading dynamics. We prepare polydimethylsiloxane (PDMS) networks with varied rheological properties by adjusting the ratio of amine and aldehyde groups and curing conditions. The spreading of PDMS spherical drops is investigated on surfaces with different surface energies, with the process quantified by measuring the contact length and height over time. Our findings reveal that higher modulus spheres spread more slowly, and that the spreading length increases more on high energy surfaces. This research could provide insights for developing coatings and adhesives with tunable properties by studying the interaction between transiently-crosslinked polymers and substrates during spreading.

Large diameter yet highly conductive Carbon Nanotube (CNT) yarn could have prospective control on high-tech application field spanning from electronic devices to wearable textiles; although the development of such macroscopic CNTs is extremely challenging. Especially, while fabricating CNT composite yarn with polymer, insulative nature of polymeric materials inherently propagates poor electrical conductivity to CNT yarn. To address this, we have proposed an exciting approach to fabricate large dimension, highly conductive yet flexible CNT-Thermoplastic Polyurethane (TPU) composite yarn through unidirectional compression-stretching process. Our technique allowed TPU molecules to be well dispersed into inner and inter-CNT bundles facilitating well flexibility while the simultaneous functions of pressure and tension allowed more closely packed CNTs network within densified CNT yarn reducing the inherent voids and contact resistance. The consequent yarn possessed high conductivity of 1613 S/cm, attractive mechanical performance (tensile strength 1.3 GPa, Young's modulus 12 GPa, toughness 100.75 MJ/m³), exceptional anti-abrasive ability (up to 46,350 cycles) endowing its multidirectional adaptability for smart textiles. Moreover, the desirable E-heating performance together with excellent electrical stability allows successful exploitation of the prepared CNT yarn as stretchable heater. Such amazing integrated characteristics may allow the resultant yarn to replace traditional carbon fiber in various high-tech arena as well.

The lack of endothelial layer hinders the use of decellularized corneal stroma in keratoplasty, resulting in adverse effects, such as non-specific protein adsorption and corneal oedema after implantation, which leads to rapid failure of the ophthalmic implants. In this study, superhydrophilic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) was gently introduced to the porcine-derived decellularized corneal stroma matrix (pDCSM), aiming to resist undesirable biofilm adsorption within the ocular environment. After complete decellularization, the pDCSM was first methacrylated by the integration of methacrylic anhydride. Consecutively, PMPC was only grafted from the back surface (endothelium side) of the methacrylated pDCSM through surface-initiated free radical polymerization. This one-side surface-modified pDCSM not only retained good optical transmittance and mechanical properties that were comparable to the untreated pDCSM, but both surfaces of the same artificial cornea also showed non-cytotoxicity and good biocompatibility. Moreover, the PMPC-grafted back surface exhibited considerable antifouling properties that resisted both protein and cell adhesion. Consequently, such Janus-like artificial cornea holds great promise in future ophthalmic applications, which may serve as a springboard for the design of versatile decellularized extracellular matrix based biomedical implants with Janus-like properties.

High-voltage responsiveness and poor mechanical properties hindered the practical applications of electro-induced shape-changing hydrogels (EISCHs). In previous work, mechanical properties were improved simply by increasing the degree of crosslinking, which resulted in reduced deformation capacity. Therefore, the nanocomposite technique of reinforcing nondeformable hydrogels' mechanical properties was introduced into EISCHs, resulting in the successful synthesis of Poly (N-isopropylacrylamide-co-5-acrylamido-1,10-phenanthroline bis (1,10-phenanthroline) iron (II))/hydrophilic-treated hydroxylated carbon nanofibers (P(NIPAM-Fe(phen)₃)/HMWCNFs) nanocomposite shape-changing hydrogel that exhibits outstanding mechanical properties, doesn't have its deformation ability weakened and possesses low-voltage responsiveness in this work. The impact of various hydrophilic-treated hydroxylated carbon nanofibers (HMWCNFs) content on hydrogels' structure, swelling, crosslinking, mechanics and electro-induced shape-changing properties was investigated. As the HMWCNFs content increased (0.2%–1.0%), the tensile and compressive strengths increased, marking 6.67 times and 2.91 times rise over hydrogel without HMWCNFs. The deformation ability of P(NIPAM-Fe(phen)₃/HMWCNFs) hydrogel was higher than without HMWCNFs at minimum response voltage 10 V. The physical entanglements and hydrogen bonding between HMWCNFs and polymer chains reduced adhesion energy and provided energy dissipation. HMWCNFs, as a conductive filler, facilitated electron transfer. The hydrogel swelled and shrank due to the transition between 5-acrylamido-1,10-phenanthroline bis (1,10-phenanthroline) iron (II) (Fe(phen)₃) network iron (II) and iron (III) states under low-voltage stimulation.

The stability of agglomerating agent is an important parameter to evaluate its value, which is of great significance for its subsequent transportation, storage, and practical application. In this study, a highly stable agglomerating agent synergistically stabilized by sodium dodecyl sulfate (SDS) and SiO₂ was synthesized. The stabilization mechanism of the agglomerating agent and its agglomeration effect on polybutadiene latex (PBL) were studied. First, the mean particle size, particle size distribution, interfacial tension, and viscosity of the agglomerating agent emulsion stabilized by SDS/SiO₂ has been investigated and compared with those of conventional emulsion stabilized by SDS. The results show that when the SDS concentration is lower than 0.125%, the presence of SiO₂ can significantly increase the anticoagulation ability of agglomerating agent particles in the polymerization process. Furthermore, noting that agglomerating agent emulsions stabilized by SDS/SiO₂ exhibited high stability even pH, centrifugation, storage, and temperatures changed in wide range. In addition, the stability of the agglomerating agents synergistically stabilized by surfactants and SiO₂ nanoparticles is better than using them alone. Then, the stability mechanism of SiO₂ in the agglomerating agent was investigated. The results revealed that the SiO₂ particles are tightly adsorbed on the surface of the agglomerating agent particles through hydrogen bonding and play a physical isolation role. Finally, the 100 nm PBL was enlarged to 469 nm by a synthetic agglomerating agent. Surprisingly, the SiO₂ particles show excellent physical isolation role, not only in agglomerating agent but also in agglomerated PBL. Our findings provide novel insights into the synthesis of highly stable agglomerating agent and improve the practical application significance of subsequent PBL agglomerations and ABS properties.

In this study, the hydroxyl modified hollow glass microsphere (HM-HGM) is added to different foaming slurries of isocyanate-based polyimide foam (IBPIF) at varying ratios, and different bonding effects are formed to optimize the dispersion behavior. Then, the novel HGM composited IBPIF (IBPIF/HGM) is prepared. Hydroxyl groups on HM-HGM establish hydrogen bonding effect with pyromellitic acid dimethyl ester and dimethyl formamide in the white slurry and react with isocyanate groups in the black slurry. The cell structure of IBPIF is altered to improve its sound absorption performance and mechanical behaviors. Compared with IBPIF/HGM-0, the average cell size of IBPIF/HGM-1 and BPIF/HGM-5 decreases significantly. The sound absorption performance and mechanical behaviors of them are improved to some extent. Compared with samples in which the HM-HGM is added alone to a single slurry, when the dosage ratio of HM-HGM in black and white slurries is 1:1, IBPIF/HGM-3 has more uniform cell structure. The change of IBPIF cell structure by the introduction of HM-HGM and the unique structure of HM-HGM can enhance the sound absorption performance and mechanical behaviors of IBPIF. The design idea of different bonding mechanisms significantly provides technical assistance to enhance the acoustic performance of polymeric foam materials.