Langmuir monolayers of lignins obtained with different isolation methods

Langmuir monolayers of fractions of cork suberin extract

“…The rationale behind the choice of experiments with Langmuir monolayers of suberin was based on the finding that for complex natural polymers important information is obtained from the effects of different functional groups comprising the polymer [8]. We have therefore manipulated the suberin extract to be able to identify these effects, as will be explained below.…”

“…These results clearly suggest that this suberin fraction could hardly establish any interaction with the water surface and thus confirm the hydrophobic nature of suberan which is thought to be composed by long-chain aliphatic structures linked via glycerol units [12,15]. Despite the fact that some authors suggest that upon suberin depolymerisation the residue may contain significant quantities of aromatics some of which are associated with lignin structures [15], notice should be made that the surface properties of sample 5 are significantly distinct from those observed for lignin samples [8].…”

“…A variety of properties can be exploited in such materials, including biodegradability and biocompatibility, but an obvious difficulty, particularly for those having complex structures, lies in the need to establish structure-function relationships, particularly at the molecular level. In this context, the Langmuir monolayer technique, which is normally used to study monolayers at the air-water interface of synthetic amphiphilic polymers and fabricate Langmuir-Blodgett (LB) films for a variety of applications [4,5], has also been used to study complex natural polymers such as lignin and cellulose [6][7][8][9]. Langmuir films, however, have not been used in studies of suberin extracts -to the best of our knowledge.…”

“…Due to the amphiphilic nature of the suberin extract the Langmuir monolayer technique appears to be promising to obtain further insight into its surface properties at the molecular level, which has prompted us to report the monolayer results to be presented here. We build upon our experience with lignins, in which we found essential to identify the contributions from the various material components to the properties of the final film properties [8]. Accordingly, we have manipulated the suberin extract with chemical treatments and fractionation methods to obtain components that were rich in carboxylic acids or methyl esters, of different molecular weights, and investigated the film properties of the suberan, a high molecular weight non-hydrolysable aliphatic fraction of suberin [25].…”

Ultrathin films of lignins as a potential transducer in sensing applications involving heavy metal ions

“…The fabrication of monomolecular films onto the water subphase through the Langmuir technique [5] has been used as a unique method to exploit either the molecular structure or the spatial arrangement of the lignins [6][7][8][9][10][11][12][13]. However, technological applications of these and any other material in electronic devices must involve the possibility of making thin films onto solid substrates.…”