Use of Nanotechnology to Mitigate Biofouling in Stainless Steel Devices Used in Food Processing, Healthcare, and Marine Environments

In humid environments, the formation of biofilms and microfouling are known to be the detrimental processes that first occur on stainless steel surfaces. This is known as biofouling. Subsequently, the conditions created by metabolites and the activity of organisms trigger corrosion of the metal and accelerate corrosion locally, causing a deterioration in, and alterations to, the performance of devices made of stainless steel. The microorganisms which thus affect stainless steel are mainly algae and bacteria. Within the macroorganisms that then damage the steel, mollusks and crustaceans are the most commonly observed. The aim of this review was to identify the mechanisms involved in biofouling on stainless steel and to evaluate the research done on preventing or mitigating this problem using nanotechnology in humid environments in three areas of human activity: food manufacturing, the implantation of medical devices, and infrastructure in marine settings. Of these protective processes that modify the steel surfaces, three approaches were examined: the use of inorganic nanoparticles; the use of polymeric coatings; and, finally, the generation of nanotextures.

Visualization and monitoring of damaging-healing processes of polymers by AIEgen-loaded multifunctional microcapsules

Polymeric materials play an essential and ubiquitous role in modern societies, but they are inevitably damaged during service, which can lead to compromised performance or even direct failure. The sensitive detection and dynamic monitoring of the health states of polymers is thus crucial to increase their reliability, safety, and lifetime. Herein, a facile fluorescence-based approach that can achieve the nondestructive, on-site, real-time, full-field, and sensitive visualization and monitoring of damaging-healing processes of polymers is demonstrated. By embedding novel UV-blocking microcapsules containing a diisocyanate solution of aggregation-induced emission luminogens (AIEgens) into a polymer matrix, the damaged regions of the composite show turn-on fluorescence and dual signal changes in both fluorescence intensity and fluorescence color can be observed during the healing processes. The invisible information of the static health states and dynamic healing processes can be directly and semi-quantitatively visualized by naked eyes based on the collective effects of AIE and twisted intramolecular charge transfer. In addition to the autonomous damage-reporting, self-healing, and health indication functionalities, the microcapsule-embedded polymeric coatings possess excellent photo- and water-protection capabilities, which are appealing to various practical applications.

Modeling of Surfactant-Enhanced Drying of Poly(styrene)-p-xylene Polymeric Coatings Using Machine Learning Technique

In this work, a machine learning technique based on a regression tree model was used to model the surfactant enhanced drying of poly(styrene)-p-xylene coatings. The predictions of the developed model based on regression trees are in excellent agreement with the experimental data. A total of 16,258 samples were obtained through experimentation. These samples were separated into two parts: 12,960 samples were used for the training of the regression tree, and the remaining 3298 samples were used to test the tree’s prediction accuracy. MATLAB software was used to grow the regression tree. The mean squared error between the model-predicted values and actual outputs was calculated to be 8.8415 × 10−6. This model has good generalizing ability; predicts weight loss for given values of time, thickness, and triphenyl phosphate; and has a maximum error of 1%. It is robust and for this system, can be used for any composition and thickness for this system, which will drastically reduce the need for further experimentations to explain diffusion and drying.

Double layered Polymeric Coatings for Corrosion Protection of Steel

Corrosion is one of the challenging issues faced by many industries, causing substantial economic losses every year due to the degradation of metallic parts, raising many safety concerns. Therefore, it is of utmost relevance to developing strategies that can repair the damaged part of the coatings to protect the base metal and restrict the initiation of corrosion. Towards this direction, the concept of double-layered polymeric coatings (DLPCs) for corrosion protection is introduced as a novel strategy to bring different healing functionalities into coating matrices. The developed DLPCs are composed of a top layer containing 5wt. % of melamine urea-formaldehyde microcapsules (MUFMC) encapsulating boiled linseed oil (self-healing agent), and bottom layer having 3wt. % benzotriazole (corrosion inhibitor) loaded into halloysite nanotubes (HNTs). The DLPCs were developed on mild steel substrate employing a doctor blade technique. The electrochemical analyses indicates that the DLPCs demonstrate improved corrosion resistant properties. This improved performance can be ascribed to the efficient triggering of the individual carriers in the quarantined matrix, resulting in enhanced corrosion efficiency of the DLPCs. The promising characteristics of DLPCs make them suitable for many potential industrial applications.

Functional Tapered Fiber Devices Using Polymeric Coatings

A wide variety of fiber devices can be created by adding special coatings on tapered sections of optical fibers. In this work we present the fundamentals for the fabrication of tapered optical fibers coated with functional polymers. The required aspects of light propagation in tapered sections of optical fibers are introduced and the relevant parameters enabling light interaction with external media are discussed. A special case of interest is the addition of polymeric coatings with prescribed thicknesses in the tapered sections allowing for adjusting the light propagation features. We assess the use of liquid polymer coatings with varying thicknesses along the taper profile that can be tailored for tuning the transmission features of the devices. Hence, we introduce a methodology for obtaining coatings with predefined geometries whose optical properties will depend on the polymer functionality. As demonstrated with numerical simulations, the use of functional polymer coatings in tapered optical fibers allows for obtaining a wide variety of functionalities. Thus, controlled polymer coating deposition may provide a simple means to fabricate fiber devices with adjustable transmission characteristics.