We explore the application of a high-temperature precursor delivery system for depositing high boiling point organosilicate precursors on plastics using atmospheric plasma. Dense silica coatings were deposited on stretched poly(methyl methacrylate), polycarbonate and silicon substrates from the high boiling temperature precursor, 1, 2-bis(triethoxysilyl)ethane, and from two widely used low boiling temperature precursors, tetraethoxysilane and tetramethylcyclotetrasiloxane. The coating deposition rate, molecular network structure, density, Young's modulus and adhesion to plastics exhibited a strong dependence on the precursor delivery temperature and rate, and the functionality and number of silicon atoms in the precursor molecules. The Young's modulus of the coatings ranged from 6 to 34 GPa, depending strongly on the coating density. The adhesion of the coatings to plastics was affected by both the chemical structure of the precursor and the extent of exposure of the plastic substrate to the plasma during the initial stage of deposition. The optimum combinations of Young's modulus and adhesion were achieved with the high boiling point precursor which produced coatings with high Young's modulus and good adhesion compared to commercial polysiloxane hard coatings on plastics.

The freshwater scarcity and inadequate access to clean water globally have rallied tremendous efforts in developing robust technologies for water purification and decontamination, and heterogeneous catalysis is a highly-promising solution. Sub-nanometer-confined reaction is the ultimate frontier of catalytic chemistry, yet it is challenging to form the angstrom channels with distributed atomic catalytic centers within, and to match the internal mass transfer and the reactive species’ lifetimes. Here, we resolve these issues by applying the concept of the angstrom-confined catalytic water contaminant degradation to achieve unprecedented reaction rates within 4.6 Å channels of two-dimensional laminate membrane assembled from monolayer cobalt-doped titanium oxide nanosheets. The demonstrated degradation rate constant of the target pollutant ranitidine (1.06 ms−1) is 5–7 orders of magnitude faster compared with the state-of-the-art, achieving the 100% degradation over 100 h continuous operation. This approach is also ~100% effective against diverse water contaminates with a retention time of <30 ms, and the strategy developed can be also extended to other two-dimensional material-assembled membranes. This work paves the way towards the generic angstrom-confined catalysis and unravels the importance of utilizing angstrom-confinement strategy in the design of efficient catalysts for water purification.

We report on the synthesis of hard, adhesive, and highly transparent bilayer organosilicate thin films on large poly(methyl methacrylate) substrates by atmospheric plasma, in ambient air, at room temperature, in a one-step process, using a single precursor. The method overcomes the challenge of fabricating coatings with high mechanical and interfacial properties in a one-step process. The bottom layer is a carbon-bridged hybrid silica with excellent adhesion with the poly(methyl methacrylate) substrate, and the top layer is a dense silica with high Young’s modulus, hardness, and scratch resistance. The bilayer structure exhibited ~100% transmittance in the visible wavelength range, twice the adhesion energy and three times the Young’s modulus of commercial polysiloxane sol–gel coatings.

Oxygen atmospheric plasma was used to pretreat polycarbonate (PC) and stretched poly(methyl methacrylate) (PMMA) surfaces in order to enhance the adhesion of the dense silica coatings deposited by atmospheric plasma on the polymer substrates. The treatment time and chemical structure of the polymers were found to be important factors. For PC, a short treatment increased the adhesion energy, while longer treatment times decreased the adhesion. In contrast, plasma pretreatment monotonically decreased the adhesion of PMMA, and pristine PMMA exhibited much higher adhesion than the PC counterpart. We found that adhesion enhancement was achieved through improved chemical bonding, chain interdiffusion, and mechanical interlocking at the coating/substrate interface, after a short atmospheric plasma treatment. Decreased adhesion resulted from overoxidation and low-molecular-weight weak layer formation on the polymer surface by prolonged atmospheric plasma treatment. The dramatic differences in the behavior of PC and PMMA in relation to the plasma treatment time were due to their dissimilar resistance to atmospheric plasma exposure.

Transparent polymers are widely used in many applications ranging from automotive windows to microelectronics packaging. However, their intrinsic characteristics, in particular their mechanical properties, are significantly degraded with exposure to different weather conditions. For instance, under humid environment or UV-irradiation, polycarbonate (PC) undergoes depolymerization, leading to the release of Bisphenol A, a molecule presumed to be a hormonal disruptor, potentially causing health problems. This is a serious concern and the new REACH (Registration, Evaluation, Authorization and Restriction of Chemical substances) program dictates that materials releasing Bisphenol A should be removed from the market by January 1st, 2015 (2012-1442 law). Manufacturers have tried to satisfy this new regulation by depositing atop the PC a dense oxide-like protective coating that would act as a barrier layer. While high hardness, modulus, and density can be achieved by this approach, these coatings suffer from poor adhesion to the PC as evidenced by the numerous delamination events occurring under low scratch constraints. Here, we show that the combination of a N 2 /H 2-plasma treatment of PC before depositing a hybrid organicinorganic solution leads to a coating displaying elevated hardness, modulus, and density, along with a very high adherence to PC (> 20 J/m 2 as measured by double cantilever beam test). In this study, the sol-gel coatings were composed of hybrid O/I silica (based on organoalkoxysilanes and colloidal silica) and designed to favor covalent bonding between the hybrid network and the surface treated PC, hence increasing the contribution of the plastic deformation from the substrate. Interestingly, doublecantilever beam (DCB) tests showed that the coating's adhesion to PC was the same irrespective of the organoalkoxysilanes/ colloidal silica ratio. The versatility of the sol-gel deposition techniques (dip-coating, spray-coating, etc.), together with the excellent mechanical properties and exceptional adherence of this hybrid material to PC should lead to interesting new applications in diverse fields: optical eyeglasses , medical materials, packaging, and so forth.

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Cells were continuously exposed to oxidative damage by overproduction of reactive oxygen species (ROS) when they contacted implanted biomaterials. The strategy to prevent cells from oxidative injures remains a challenge. Inspired by the antioxidant defense system of cells, we constructed a biocompatible and ROS-responsive architecture on the substrate of styrene-b-(ethylene-co-butylene)-b-styrene elastomer (SEBS). The strategy was based on fabrication of architectures through reactive electrospinning of mixture including SEBS, acylated Pluronic F127, copolymer of poly(ethylene glycol) diacrylate and 1,2-ethanedithiol (PEGDA-EDT), and antioxidants (AA-2G) and ROS-triggered release of AA-2G from microfibers to detoxify the excess ROS. We demonstrated that the stable and hydrophilic architecture was constructed by phase separation of SEBS/F127 components and cross-linking between polymer chains during electrospinning; the ROS-responsive fibers controlled the release of AA-2G and the interaction of AA-2G with ROS reduced the oxidative damage to cells. The bioinspired architecture not only reduced mechanical and oxidative damage to cells but also maintained normal ROS level for physiological hemostasis. This work provides basic principles to design and develop antioxidative biomaterials for implantation in vivo.

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