A Vitrimer Acts as a Compatibilizer for Polyethylene and Polypropylene Blends.

Polymer compatibilization plays a critical role in achieving polymer blends with favorable mechanical properties and enabling efficient recycling of mixed plastic wastes. Nonetheless, traditional compatibilization methods often require tailored designs based on the specific chemical compositions of the blends. In this study, we propose a new approach for compatibilizing polymer blends using a dynamically crosslinked polymer network, known as vitrimers. By adding a relatively small amount (1-5 w/w%) of a vitrimer made of siloxane-crosslinked high-density polyethylene (HDPE), we successfully compatibilized unmodified HDPE and isotactic polypropylene (iPP). The vitrimer-compatibilized blend exhibited enhanced elongation at break (120 %) and smaller iPP domain sizes (0.4 µm) compared to the control blend (22 % elongation at break, 0.9 µm iPP droplet size). Moreover, the vitrimer-compatibilized blend showed significantly improved microphase stability during annealing at 180 °C. This straightforward method shows promise for applications across various polymer blend systems.

Usefulness of three-dimensional imaging in a flexible endoscopic surgery platform with multi-degrees-of-freedom articulating devices.

BACKGROUND AND AIMS: Recent studies on endoscopic submucosal dissection have aimed to reduce the difficulty of the procedure by using multi-degrees-of-freedom articulating devices. In this study, we evaluated the usefulness of adding three-dimensional (3D) video imaging into simulated endoscopic submucosal dissection tasks using multi-degrees-of-freedom devices. METHODS: We designed an endoscopic platform with a 3D camera and two multi-degrees-of-freedom devices. Four ex vivo bench tasks were created, and a crossover study comparing 2D and 3D conditions was conducted on 15 volunteers. In each task, performance such as procedure time and accuracy were objectively evaluated. Additionally, a comprehensive visual analogue scale questionnaire was conducted. RESULTS: In the tasks simulating submucosal flap grasping, marking, and full-area incision, the use of 3D imaging significantly improved the speed and accuracy of the multi-degrees-of-freedom device manipulation (p < .01). No significant differences were observed in the task that simulated the dissection procedure. Furthermore, it appears that the accuracy of recognizing curved surfaces may be reduced in the 3D environment. Operators reported subjective increases in recognizability and operability with the 3D camera, along with an increase in asthenopia (p < .01). CONCLUSIONS: 3D vision improves the technical accuracy of certain simulated multi-degrees-of-freedom endoscopic submucosal dissection tasks and subjectively improved operating conditions, at the cost of increased eye strain.

Fluoride-Catalyzed Siloxane Exchange as a Robust Dynamic Chemistry for High-Performance Vitrimers.

Sustainable development of new technologies requires materials having advanced physical and chemical properties while maintaining reprocessability and recyclability. Vitrimers are designed for this purpose; however, their dynamic covalent chemistries often have drawbacks or are limited to specialized polymers. Here, fluoride-catalyzed siloxane exchange is reported as an exceptionally robust chemistry for scalable production of high-performance vitrimers through industrial processing of commodity polymers such as poly(methyl methacrylate), polyethylene, and polypropylene. The vitrimers show improved resistance to creep, heat, oxidation, and hydrolysis, while maintaining excellent melt flow for processing and recycling. Furthermore, the siloxane exchange between different vitrimers during mechanical blending results in self-compatibilized blends without any compatibilizers. This offers a general, scalable method for producing sustainable high-performance vitrimers and a new strategy for recycling mixed plastic wastes.

Crystallization-Induced Emission of Azobenzene Derivatives.

Most azobenzene derivatives are utilized as well-defined photoresponsive materials, but their emission properties have not been of great interest as they are relatively poor. Here, we report crystallization-induced emission (CIE) based on the suppression of the photoisomerization of azobenzene derivatives. Although these molecules show negligible emission in solution, their microcrystals exhibit intense emission from the azobenzene moieties as a result of CIE. Upon rapid precipitation, fine particles with low crystallinity were kinetically formed and underwent CIE over time with a concomitant increase in crystallinity. Furthermore, we demonstrated "photocutting" of an emissive single crystal using a strong laser by a combination of CIE behavior and photomelting based on the photoisomerization of the azobenzene moiety. Our results regarding the CIE behavior of azobenzene derivatives in addition to their photoisomerization can provide a new platform for developing photoresponsive luminescent materials.