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Phage display biopanning with Illumina next-generation sequencing (NGS) is applied to reveal insights into peptide-based adhesion domains for polypropylene (PP). One biopanning round followed by NGS selects robust PP-binding peptides that are not evident by Sanger sequencing. NGS provides a significant statistical base that enables motif analysis, statistics on positional residue depletion/enrichment, and data analysis to suppress false-positive sequences from amplification bias. The selected sequences are employed as water-based primers for PP-metal adhesion to condition PP surfaces and increase adhesive strength by 100% relative to nonprimed PP.
Various methods have been used for introducing fire retardant additives into polymers. Deposition of thick fire retardant coatings directly onto polymer substrates is an alternative technique. An important Advantage of the coating technique is the preservation of the physical and chemical integrity of the polymer material. Moreover, the fire retardancy of the polymer materials can be achieved following their production. Suitable coating materials are inorganics, intumescent, char-forming, oxygendiluting, and cooling or radical quenching layers. The most important problem is to achieve sufficient coating thickness to withstand the direct attack of flame and to protect the polymer bulk from pyrolysis, otherwise blistering of coating, caused by emitted pyrolysis gases, is often observed.
To avoid blistering of coating, the adhesion between polyolefin Substrate and fire retardant coating has to be extraordinarily high.
In order to achieve such a high level of adhesion, the polymer surface has to be modified with adhesion-promoting functional groups. The deposition of thin plasma polymers as adhesion-promoting layers with NH2, OH or COOH groups has been the most suited method. These functional groups are able to form covalent bonds and other interactions between the fire-resistant coating and the plasma-modified polyolefin substrate.
Additionally, the plasma polymer counteracts the strong mechanical stresses in the laminate on exposure to high temperatures by its flexibility. The thick fire retardant coatings were chosen based on “green” ecological aspects to avoid flame-initiated emission of toxic or corrosive gases and remains of toxic char.
Various methods have been used for introducing fire retardant additives into polymers. Deposition of thick fire retardant coatings directly onto polymer substrates is an alternative technique. An important advantage of the coating technique is the preservation of the physical and chemical integrity of the polymer material. Moreover, the fire retardancy of the polymer materials can be achieved following their production. Suitable coating materials are inorganics, intumescent, char-forming, oxygendiluting, and cooling or radical quenching layers. The most important problem is to achieve sufficient coating thickness to withstand the direct attack of flame and to protect the polymer bulk from pyrolysis, otherwise blistering of coating, caused by emitted pyrolysis gases, is often observed. To avoid blistering of coating, the adhesion between polyolefin substrate and fire retardant coating has to be extraordinarily high.
In order to achieve such a high level of adhesion, the polymer surface has to be modified with adhesion-promoting functional groups. The deposition of thin plasma polymers as adhesion-promoting layers with NH2, OH or COOH groups has been the most suited method. These functional groups are able to form covalent bonds and other interactions between the fire-resistant coating and the plasma-modified polyolefin substrate. Additionally, the plasma polymer counteracts the strong mechanical stresses in the laminate on exposure to high temperatures by its flexibility.
The electrospray ionization (ESI) method was used for deposition of thin films of poly(acrylic acid) (PAA) onto ZSM-5, Cu/ZSM-5 and Ag-Cu/ZSM-5 zeolites. This method allowed the formation of uniform polymer films of controlled thickness on conductive substrates.
The zeolites were prepared home-made. The effect of incorporation of Cu (5 wt.%) and Ag-Cu (1+4 wt.%) onto ZSM-5 on its particle size, unit cell parameters and crystallinity was investigated.
The deposited PAA layer acts as a common dispersing agent with its ionic COOH (COO-) groups. The antibacterial activity towards the bacterial strains such as Staphylococcus pneumonia (S. Pneumonia), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) as Gram positive and Gram negative bacteria, respectively, and Aspergillus fumigatus (A. fumigatus), Candida albicans (C. albicans) as Fungi was evaluated. The chemical and physical modifications of ZSM-5, Cu/ZSM-5 and Ag-Cu/ZSM-5 surfaces were characterized by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, atomic force microscopy and X-ray diffraction.
The Cu/ZSM-5 and Ag-Cu/ZSM-5 nanocomposites coated with a 10 nm thick PAA layer exhibit significant antibacterial activity. The carboxyl (¬-COOH) or the corresponding carboxylate groups (¬-COO-) interact with Cu2+ and Ag+ ions by formation of ionic bonds (¬-COO-Ag+ or 2 ¬-COO->Cu2+). Moreover, short exposure to light and temperature has reduced Cu2+ and Ag+ to Cu0 and Ag0.
The repair of earthen structures is not an easy task. Earth as a construction material has comparatively weak mechanical properties. It is also susceptible towards liquid water, were it can lose cohesion very quickly if certain moisture contents are exceeded. Repair concepts of structures built with such materials are therefore challenging. Historical earthen structures often exhibit damages in form of extensive cracking, which may have been caused by static or dynamic loads. Frequently these cracks are insufficiently or inappropriately repaired because of lack of knowledge and / or technology. In particular, the behaviour of crack repair by grouting poses a challenge in earthen materials and demands specific requirements for the grouting mortar, such as low water content, good water retention, low shrinkage. Grouting materials require additional specifications such as compatible strengths and Young’s modulus as well as good adhesion to the earthen substrates. In addition, grouts have to be sufficiently flowable to fill small cracks and voids without segregation or bleeding. Therefore, the rheological behaviour has to be well understood and controlled to gain the desired effects.The repair of cracks in earthen buildings is traditionally done by stuffing manually mortar into the gap. Naturally, this method is only usable for cracks with large widths. Another disadvantage is that cracks going through thicker walls cannot be completely reached by the tools used for stuffing the mortar into the crack. Lime based grouts for earthen materials were usually used for re-attachment of plasters but less for structural reasons.Due to the nature of earthen materials grouts based on formulated or hydraulic lime (according to the definition in EN 459-1) have to meet considerable demands on a variety of properties, which are related to compatibility, durability and in particular to the ability of being injected. The goal of this study was to create a grout, which can be used to re-establish structural continuity in cracked earthen masonry or other massive earth walls (rammed earth and cob) with the focus on grouting cracks. The grout material was based on hydrated lime (calcium hydroxide) with additions of pozzolana and lime stone filler.
The study presents the results from the development of a grouting material based on hydrated lime with addition of pozzolana, which is referred to as hydraulic lime, suitable for the repair of cracks in a variety of earthen building techniques. The goal was to develop a material also compatible with earthen structures exposed to dynamic loads. The grouting mortar was designed to be adaptable in strength properties and at the same time to have sufficient robustness for preparation and use on the construction site.
Results showed a satisfactory performance of the grout concerning fresh and hardened mortar properties as well as injectability.
The adhesion of thick poly(allylamine)-polyphosphate layers (1 µm) deposited by the wet-chemical layer-by-layer technique (LbL) onto polyethylene or polystyrene (each 100 µm) was very low. To promote the adhesion of these LbL layers the polyolefin substrates were oxidized at the surface by short exposure to the oxygen plasma (2 or 5 s) and subsequently coated with an interlayer of plasma-deposited poly(allylamine) or poly(allyl alcohol) (100 nm). The plasma polymer interlayers have improved strongly the adhesion between polyolefin substrates and polyphosphate coatings. Such phosphate coatings are interesting for life sciences (nucleotide formation) but also for fire retardancy in combination with N-rich compounds such as melamine.
The intention was to prefer chemical and hydrogen bonds for adhesion promoting because of their high binding energy. Therefore, the introduced oxygen-containing groups at the polyolefin surface could interact with the OH or NH2 groups of the adhesion-promoting plasma polymer interlayer. These groups were also able to interact strongly with the poly(allylamine)-polyphosphate topcoating.
The coated polyolefins were investigated using Fourier Transform Infrared Spectroscopy in Attenuated Total Reflectance mode (FTIR-ATR), X-ray Photoelectron Spectroscopy (XPS), Thermo-Gravimetric Analyses (TGA) and Atomic Force Spectroscopy (AFM) and 90° peel test.