A moisture-absorbing and abrasion resistant transparent coating on polystyrene

A common phenomenon concerning cold surfaces which are subjected to a warmer, more humid atmosphere is condensation in the form of water droplets (fogging) or even ice crystals (icing). Thus, a previously transparent object becomes opaque because light is scattered by the droplets or crystals. This may impair the usability of that object. We developed an anti-fogging/icing coating which overcomes the problem of fogging and icing by being able to absorb the condensing water and preventing it from crystallizing. The coating consists of poly(1-vinyl-2-pyrrolidone) (PVP) crosslinked by UV light using hydrogen peroxide (H2O2). Benzophenone (BP) is used to attach PVP to the surface of the polystyrene (PS) substrate. At temperatures as low as -60°C, the PVP coating can absorb up to 70 wt% of water and still inhibit its crystallization. However, at surface temperatures of around -18°C, opacity is only observable at 150 wt% of absorbed water and higher. An increasing coating thickness as well as a decreasing crosslink density improves the anti-fogging/icing effect because the coating can absorb more water. The abrasion resistance of the coating is impaired by a decreasing crosslink density

Sol-gel coatings with lime repellent properties

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Calcification of surfaces by hard water represents a major issue for sanitary installations. Calcium carbonate precipitates forming crusts of lime that are difficult to remove. Much effort has been undertaken to avoid scaling, most methods require chemicals or create waste. We constructed a test rig which allows for the controlled calcification of various substrates. It is found that all solid surfaces investigated calcify more or less evenly. On the other hand, surface bound poly(ethylene glycol), PEG, is known to prevent the non-specific adsorption of biomolecules. PEG coated surfaces find their use in a variety of applications. Here we show that glass and plastics, such as polyethylene, polypropylene and acrylonitrile-butadiene-styrene, can be efficiently made lime repellent by the use of sol-gel coatings containing a PEG bearing silane. It is shown that the amount of scaling is drastically reduced. Prior to coating, plastics have to be pretreated by oxygen plasma and an adhesion promoter has to be employed

Sol-gel coatings with lime repellent properties

Calcification of surfaces by hard water represents a major issue for sanitary installations. Calcium carbonate precipitates forming crusts of lime that are difficult to remove. Much effort has been undertaken to avoid scaling, most methods require chemicals or create waste. We constructed a test rig which allows for the controlled calcification of various substrates. It is found that all solid surfaces investigated calcify more or less evenly. On the other hand, surface bound poly(ethylene glycol), PEG, is known to prevent the non-specific adsorption of biomolecules. PEG coated surfaces find their use in a variety of applications. Here we show that glass and plastics, such as polyethylene, polypropylene and acrylonitrile-butadiene-styrene, can be efficiently made lime repellent by the use of sol-gel coatings containing a PEG bearing silane. It is shown that the amount of scaling is drastically reduced. Prior to coating, plastics have to be pretreated by oxygen plasma and an adhesion promoter has to be employe

Gathering Global Perspectives to Establish the Research Priorities and Minimum Data Sets for Degenerative Cervical Myelopathy:Sampling Strategy of the First Round Consensus Surveys of AO Spine RECODE-DCM

STUDY DESIGN: Survey.INTRODUCTION: AO Spine Research Objectives and Common Data Elements for Degenerative Cervical Myelopathy (AO Spine RECODE-DCM) is an international initiative that aims to accelerate knowledge discovery and improve outcomes by developing a consensus framework for research. This includes defining the top research priorities, an index term and a minimum data set (core outcome set and core data elements set - core outcome set (COS)/core data elements (CDE)).OBJECTIVE: To describe how perspectives were gathered and report the detailed sampling characteristics.METHODS: A two-stage, electronic survey was used to gather and seek initial consensus. Perspectives were sought from spinal surgeons, other healthcare professionals and people with degenerative cervical myelopathy (DCM). Participants were allocated to one of two parallel streams: (1) priority setting or (2) minimum dataset. An email campaign was developed to advertise the survey to relevant global stakeholder individuals and organisations. People with DCM were recruited using the international DCM charity Myelopathy.org and its social media channels. A network of global partners was recruited to act as project ambassadors. Data from Google Analytics, MailChimp and Calibrum helped optimise survey dissemination.RESULTS: Survey engagement was high amongst the three stakeholder groups: 208 people with DCM, 389 spinal surgeons and 157 other healthcare professionals. Individuals from 76 different countries participated; the United States, United Kingdom and Canada were the most common countries of participants.CONCLUSION: AO Spine RECODE-DCM recruited a diverse and sufficient number of participants for an international PSP and COS/CDE process. Whilst PSP and COS/CDE have been undertaken in other fields, to our knowledge, this is the first time they have been combined in one process.</p

Silicone nanolayers

Silicones, also known as poly(siloxane)s, are widely used as coatings, since their low specific surface energies (typically around 20 mJ/m2) render these materials suited as water-repellant, anti-adhesion, or lubricant layers. For applications in the medical industry, the low toxicity of pure silicone grades is also of particular importance. It is, however, difficult to obtain coherent nanolayers of silicones on inorganic surfaces unless crosslinked silicones are used. However, the related application methods give raise to problems if very thin films are required, because of the poor adhesion between the silicones and the surfaces of inorganic materials such as titanium, steel, or ceramics, which are relevant as medical implants. In the following, we will present a novel patented reaction that easily allows to prepare ultrathin films of 2-5 nm thickness with linear, commercially available silicones on a a variety of surfaces

Dissertation Nr. 12333

Films of aluminium, iron and copper with thicknesses of 2000 Å and films of nickel with thicknesses of 400 Å were deposited by thermal evaporation onto crystalline silicon(100)-plates covered with 60 Å of chromium as an adhesion promoter. Films of titanium and chromium with thicknesses of 2000 Å were deposited directly onto silicon(100)-plates. Films of gold were prepared with different carriers, adhesion promoters and thicknesses. Silicon(100)-templated and mica-templated gold surfaces as well as gold surfaces on heated substrates were also used. All these films of metals were investigated with x-ray photoelectron spectroscopy (XPS), scanning tunnelling microscopy (STM), atomic force microscopy (AFM), surface profilometry, infrared spectroscopy at grazing incidence reflection (GIR), ellipsometry or contact angle measurements. Silicon(100)-plates and steel plates were also characterised. All surfaces, with the exeption of gold, show natural oxide layers, which can contain several different oxides. The roughness of the different inorganic surfaces varies from < 3 Å to 130 Å over horizontal distances of 1.5 µm and 1 mm, and the microscopic structure differs in the different substrates. On a macroscopic scale the gold surfaces on heated substrates appeared inhomogeneous by eye. Small amounts of organic impurities are present on all surfaces. The surfaces were modified with low and high molecular weight compounds by adsorption from solution. Long-chain iodoalkanes form mixed monolayers of AuI and AuC species on gold surfaces upon cleavage of the C I bonds after adsorption from solution. a,w-Diiodoalkanes react with both chain ends. The mixed monolayers are stable at room temperature in pure solvent or in the open atmosphere for at least two days. Corresponding reactions with bromoalkanes do not occur under the same reaction conditions. Adsorbed compounds which initially contained Si-H, Sn-H or Ge-H bonds form strong adhering layers on different inorganic surfaces in the presence of cis dichlorobis(styrene)platinum(II). The driving force for the formation of these layers is the activation of the Si-H, Sn-H or Ge-H bonds with a platinum compound and the transfer to the surface. Hydride-terminated polydimethylsiloxanes build up polymeric surface layers for example on gold, aluminium, titanium, chromium, iron and copper. Polyhydromethylsiloxanes form polymeric surface layers for example on gold, aluminium, iron, nickel, copper and silicon(100). These layers still contain intact Si-H groups, which can be used for further reactions on the surfaces. Methylhydrosiloxane-phenylmethylsiloxane-copolymers build up polymeric surface layers on gold and copper for example, which no longer show Si-H groups. 1,2 Dimethylsilazane-1 methylsilazane-copolymers form partly hydrolysed polymeric surface layers on gold, aluminium, iron, copper and silicon(100) for example. These layers have still intact Si H groups. Low-molecular-weight silanes build up oligomeric or polymeric siloxane layers on gold, which no longer show Si-H groups. Tributylstannane and tributylgermane form low-molecular-weight surface layers on gold and copper for example, which no longer contain Sn-H or Ge-H groups

Coatings and aerogels based on sol-gel processes

This article summarizes applications of sol-gel coatings to modify surface properties, and the process is illustrated with several examples. The use of azobenzene-modified silanes leads to a photoswitchable coating displaying light-controlled wettability. Silane coupling reactions are used to coat surfaces with polymers, in order to hinder the ice crystal growth on surfaces. Liquid-like coatings based on poly(ethylene glycol) show anti-adhesive properties to lime. The preparation of aerogels could be improved by selecting proper silanes as coupling agents to the inner surface of the pores. These examples illustrate that sol-gel processes based on silianation reactons are most promising for industrial applications