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.
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.
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