| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1695470 | Applied Clay Science | 2011 | 7 Pages |
2,4-Dichlorobenzoate (BzDC) and para-hydroxybenzoate (p-BzOH), having antimicrobial activity, have been intercalated into [Zn0.65 Al0.35(OH)2](NO3)0.35 · 0.6H2O layered double hydroxide (ZnAl-LDH), via anion-exchange reactions. The obtained nanohybrids (ZnAl-BzDC and ZnAl-p-BzOH) have been dispersed into polycaprolactone (PCL), giving rise to different composite morphologies: an exfoliated nanocomposite with ZnAl-BzDC and a microcomposite with ZnAl-p-BzOH. The different dispersion of the fillers was related to the different interactions between the two molecular anions intercalated and the LDH layers. It has been found that films of micro- and exfoliated composites and of PLC containing sodium 2,4-dichlorobenzoate or p-hydroxybenzoate simply dispersed in the polymer, release the antimicrobial species in different ways when in contact with physiologic solutions. The investigated release of the antimicrobial moieties “free dispersed” into the polymer was much faster than that of the molecular anions fixed on the inorganic compound and occurred in one step. At variance, the release from the nanohybrids occurred in two stages: the first, rapid as a “burst“, occurring in the first days, the second, very slow, extending up to many months. The diffusion of the active molecules out of the microcomposite was always slower than in the case of the exfoliated nanohybrid. Moreover a hysteresis of chemical absorption was shown by the microcomposite and this parameter has to be taken into account when tuning the release.
Graphical AbstractSchematic picture of active molecules into a polymeric matrix: a) free dispersed; b) intercalated into inorganic lamellae and dispersed as exfoliated filler; and c) intercalated into inorganic lamellae and dispersed as a microcomposite.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch Highlights► Benzoate derivatives (BzA) are intercalated into layered double hydroxide (LDH). ► Antimicrobic nanocomposites of LDH-BzA and Polycaprolactone (PCL) are prepared. ► The different composite morphologies are related to the interactions of BzA with LDH lamellae. ► BzA free dispersed into PCL are released faster than anions intercalated in LDH layers. ► The release occurred in two stages: the first, rapid as a “burst”, the second, very slow.
