Surface modification using self‐assembled layers of amphiphilic cyclodextrins

Abstract

In this study six amphiphilic cyclodextrin derivatives were prepared by esterification and used to coat five industrial products made from polypropylene, polyethylene, polyvinyl chloride, or polyurethane using a new, patented coating technology. This simple approach, which consists merely of dipping the material to be coated into a suspension of a given cyclodextrin derivative in an ethanol/water solution, was used to functionalize support materials with a coat that is stable in aqueous solutions and which renders the coated materials hydrophilic. The functionalization proved to be controllable in terms of amount of cyclodextrin on the surface and can be implemented in existing production lines without investment in advanced production equipment. It is hypothesized that the cyclodextrins order themselves in structured layers forming channel-like structures preserving the very large potential for uptake and release of active compounds that is known to cyclodextrins.

Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene

“…The six ACD derivatives were characterised with respect to the average degree of alkyl chain substitutions (DS) and location of these substitutions, as described elsewhere [ 21 ]. The structures, DS, average molecular weight, and label definitions are given in Table 3 .…”

“…It was previously shown that the coating obtained by the dip method described above is stable in the presence of water and in fact, it renders the coated material more hydrophilic [ 21 ]. Polypropylene is a very hydrophobic polymer and coating with ACDs makes the textile wettable, which in turn makes it a suitable support material for the coating even in water purification experiments as described here.…”

“…It is possible to control the amount of the coating on the PP by changing the concentration of the ACD derivative and/or the ethanol/water ratio. Previous studies proved the coating amount of PP to be fairly reproducible [ 21 ] and as the present study is focused on the uptake capacity, the results were calculated as µmol VOC per µmol CD cavity present on the PP sheet in question, that is, as a VOC:ACD ratio. Looking solely at the amount of coating achievable, the optimal ethanol/water ratio was shown to depend on the support material of choice: for PP the optimal ratio was between 40/60 and 60/40 [ 21 ].…”

“…A method for simple and fast immobilisation of CDs onto various surfaces, including polyethylene, polyvinyl chloride and polyurethane, was previously reported [ 21 ]. This method relies on the self-assembly properties of amphiphilic CDs (ACDs), which are CDs with some of the hydroxy groups substituted by alkyl chains.…”

“…One of the great advantages of this technique is that it is possible to coat different materials using the same simple technique without the requirement of specialised equipment. Several possibilities for fine-tuning the coating are possible by varying the ethanol/water ratio, changing the concentration of the ACDs in the coat solution, and/or the choice of derivative [ 21 ]. It has also been shown that the coat technology can function close to industry production speeds using a kiss-roll technique [ 22 ].…”