Enhanced adhesion effect of epoxy resin on carbon fiber-reinforced Poly(etheretherketone) via surface initiated photopolymerization of glycidyl methacrylate

Zeolite/Polymer Composites Prepared by Photopolymerization: Effect of Compensation Cations on Opacity and Gas Adsorption Applications

The fabrication of structured zeolite adsorbents through photopolymerization-based 3D printing which offers a solution to the limitations of conventional shaping techniques has been demonstrated but many parameters still need to be optimized. In this study, we studied the influence of zeolite compensation cations on the photopolymerization and the composite's properties. Modified zeolites (LTA 4 A and FAU 13X exchanged with K+ , Li+ , Sr2+ , Ca2+ or Mg2+ ) were incorporated in PEGDA with BDMK as photoinitiator, and the formulation was cured under mild conditions (LED@405 nm, room temperature, under air). Our results indicate that the nature of zeolite compensation cations affects the colorimetric properties of polymer/zeolite composites: a better translucency parameter results in higher depth of cure. After calcination at 650 °C and complete removal of PEGDA, pure zeolitic monoliths were tested for adsorption of gas molecules of interest (carbon dioxide, dichlorobenzene and water). Structured 4 A and 13X monoliths obtained by 3D printing exhibit comparable adsorption capacity to commercial beads prepared from the same zeolites. This study enhances our understanding of the photopolymerization process involved in the production of polymer/zeolite composites. These composites are used in the fabrication of zeolitic objects through 3D printing, offering potential solutions to various environmental and dental challenges.

Visualizing interface-specific chemical bonds in adhesive bonding of carbon fiber structural composites using soft X-ray microscopy

Adhesion is a technology for assembling carbon fiber (CF) reinforced polymer (CFRP), enabling them to maintain their lightweight and high-stiffness properties. Despite the importance of adhesion, the lack of a molecular-level understanding of the adhesion mechanisms has limited the reliability of adhesion for use in next-generation aircraft and automobiles. Here, we focused on the chemical-state distribution at a practical adhesive interface composed of an epoxy-based adhesive film bonded to an epoxy-based CF matrix. By fluorinating the OH group, we succeeded in visualizing the chemical state at the CF-matrix/adhesive interface using soft X-ray microscopy. The soft X-ray images exhibited a decrease in OH-related signals at the interface due to the local chemical interaction at the epoxy-epoxy adhesive interface. We also found that the N and O Kα signals were observable at the CF's surface, indicating the presence of nitrogen- and oxygen-containing functional groups. Based on these observations, we discuss the molecular-level adhesion mechanism at the CF-matrix/adhesive interface.

Photoinduced immobilization of 2-methacryloyloxyethyl phosphorylcholine polymers with different molecular architectures on a poly(ether ether ketone) surface

Poly(ether ether ketone) (PEEK) has seen increasing use in biomedical fields as a replacement for metal implants. Accordingly, the surface functionalities of PEEK are important for the development of medical devices. We have focused on the application of photoinduced reactions in PEEK to immobilize a functional polymer via radical generation on the surface, which can react with hydrocarbon groups. In this study, we used zwitterionic copolymers comprising 2-methacryloyloxyethyl phosphorylcholine (MPC) units and n-butyl methacrylate (BMA) units with various molecular architectures for surface modification. A random copolymer (poly(MPC-co-BMA) (r-PMB)), an AB-type diblock copolymer (di-PMB), and an ABA-type triblock copolymer (tri-PMB) (A segment: poly(BMA); B segment: poly(MPC)) were synthesized with the same monomer compositions. All PMBs were successfully immobilized on the PEEK surface via UV irradiation after the dip-coating process, regardless of their molecular structure. In this reaction, the alkyl group of the BMA unit functioned as a photoreactive site on the PEEK surface. This indicates that the molecular structure differences affect the surface properties. For example, compared to r-PMB and tri-PMB, di-PMB-modified surfaces exhibited an extremely low water contact angle of approximately 10°. The findings of this study demonstrate that this surface functionalization method does not require a low-molecular-weight compound, such as an initiator, and can be applied to the surface of inert PEEK through a simple photoreaction under room temperature, atmospheric pressure, and dry state conditions.

A Review of the Polymer for Cryogenic Application: Methods, Mechanisms and Perspectives

Recently, the application of polymer-based composites at cryogenic conditions has become a hot topic, especially in aerospace fields. At cryogenic temperature, the polymer becomes more brittle, and the adverse effect of thermal stress induced by temperature is more remarkable. In this paper, the research development of thermoset and thermoplastic polymers for cryogenic applications are all reviewed. This review considers the literature concerning: (a) the cryogenic performance of modified thermoset polymers and the improving mechanisms of the reported modification methods; (b) the cryogenic application potential of some commercial thermoplastic polymers and the cryogenic performance of modified thermoplastic polymers; (c) the recent advance in the use of polymer for special cryogenic environment-liquid oxygen. This paper provides a comprehensive overview of the research development of the polymer for cryogenic application. Moreover, future research directions have been proposed to facilitate its practical applications in aerospace.