Sheets of polycaprolactone (PCL) and ultra-high molecular weight polyethylene (UHMWPE) were fabricated and shaped by the Single-Point Incremental Forming process (SPIF). The performance of these biocompatible polymers in SPIF was assessed through the variation of four main parameters: the diameter of the forming tool, the spindle speed, the feed rate, and the step size based on a Box–Behnken design of experiments of four variables and three levels. The design of experiments allowed us to identify the parameters that most affect the forming of PCL and UHMWPE. The study was completed by means of a deep characterization of the thermal and structural properties of both polymers. These properties were correlated to the performance of the polymers observed in SPIF, and it was found that the polymer chains are oriented as a consequence of the SPIF processing. Moreover, by X-ray diffraction it was proved that polymer chains behave differently on each surface of the fabricated parts, since the chains on the surface in contact with the forming tool are oriented horizontally, while on the opposite surface they are oriented in the vertical direction. The unit cell of UHMWPE is distorted, passing from an orthorhombic cell to a monoclinic due to the slippage between crystallites. This slippage between crystallites was observed in both PCL and UHMWPE, and was identified as an alpha star thermal transition located in the rubbery region between the glass transition and the melting point of each polymer.

Environmental contaminants constitute an ecological and health hazard, which requires green sensing. The RAFT-MIP approach for tailor-made selective receptors enhances them via binding affinities for use in environmental contaminant sensors.

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Nanomaterial-based hybrid devices have demonstrated potential use in environmental contaminant sensing. Polymer thin films are tunable in their physicochemical properties, which makes them exploitable as functional sensing materials. For device fabrication, covalently functionalized polymer films have been explored over physically deposited layers due to their stability and have been produced via surface-initiated polymerizations as surface-grafting polymers. Specifically, surface-initiated controlled radical polymerizations (CRPs) allow the production of homogeneous organic nanothin films with tailored thicknesses. Copper-mediated CRP (CuCRP) is a rapid and facile technique to prime surface-grafting polymer films for hybrid sensor devices with improved characteristics. In this Review, we summarized the application of surface-grafting polymer-based hybrid sensor devices with an emphasis on environmental applications, and we compiled the development of CuCRP, emphasizing the discussion over its mechanism and designation and comparing it to other CRPs for the fabrication of organic thin films in sensor devices.

Product miniaturization is a constant trend in industries that demand ever-smaller products that can be mass produced while maintaining high precision dimensions in the final pieces. Ultrasonic micro injection molding (UMIM) technology has emerged as a polymer processing technique capable of achieving the mass production of polymeric parts with micro-features, while still assuring replicability, repeatability, and high precision, contrary to the capabilities of conventional processing technologies of polymers. In this study, it is shown that the variation of parameters during the UMIM process, such as the amplitude of the ultrasound waves and the processing time, lead to significant modification on the molecular structure of the polymer. The variation of both the amplitude and processing time contribute to chain scission; however, the processing time is a more relevant factor for this effect as it is capable of achieving a greater chain scission in different areas of the same specimen. Further, the presence of polymorphism within the samples produced by UMIM is demonstrated. Similarly to conventional processes, the UMIM technique leads to some degree of chain orientation, despite the fact that it is carried out in a relatively small time and space. The results presented here aim to contribute to the optimization of the use of the UMIM process for the manufacture of polymeric micro parts.

The study of SiO2 nanoparticles (NPs) and their corresponding surface modifications through octadecyltrichlorosilane (OTS) has attracted attention due to their self-cleaning, hydrophobic and superhydrophobic (SHPho) properties, which are desirable for water collection based on the dew condensation effect. Such properties have been addressed by different strategies, of which the development of hybrid superhydrophobic/hydrophilic (SHH) surfaces has shown great promise. In this research, the pairing of OTS-treated and untreated SiO2 NP layers deposited on clay substrates is investigated with the aim of exploring a hybrid SHH surface capable of enhancing dew yield behavior. Infrared analyses were conducted using FTIR to study the interaction between the clay substrate and the OTS-treated and untreated SiO2 NPs. The hybrid SHH surfaces were morphologically characterized, and contact angle (CA) measurements were performed to explore their wettability behavior. The developed hybrid SHH surfaces exhibited hydrophilic (HPhi)/SHPho properties with an improved dew yield performance. The results obtained in this article are of relevance to the development of water-harvesting devices based on hybrid SHH surfaces.

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