2.2. Polyol and metal dispersion
Sodium-montmorillonite (NaMt) was obtained through combined ion-exchange of crude bentonite (Aldrich) in aqueous NaCl solution using an effective procedure fully described elsewhere (Scheme S1 ) (Abdelkrim Azzouz et al., 2010; Thuc et al., 2010). This was followed by adding 200 g of NaMt to a 41.2:58.8 volume ratio MeOH/H2O mixture containing 200 mg of Boltorn H20 polyol dendrimer under continuous stirring for 1h at 40-60oC. The resulting organoclay, denoted as H20@NaMt was died overnight in a freeze-drying device. Similarly, Boltorn H20 was also dispersed on cellulose tissue (CT) by impregnation in 20 mL of 0.01mol/L BoltornTMH20 aqueous solution at room temperature (RT) for 1h, resulting in a H20@CT composite.
An amount of 0.2 g of NaMt-H20 was slowly mixed in a 50 mL beaker with 15 mL (33.33% and 66.66% toluene/water) aqueous solution of 0.12mol/L Cu (CH3COO)2 and (AgNO3) under vigorous stirring for 2 h. Both organoclay suspensions were dried overnight at room temperature, resulting in a first series of cation-loaded organoclays denoted as Cu2+/H20@NaMt and Ag+/H20@NaMt. A second series of samples was prepared by dropwise adding 10 mL aqueous solution of NaBH4(0.2mol/L) to both organoclay suspensions during 15 min under a nitrogen stream at ambient conditions (Scheme S2 ). The resulting metal-zero-loaded organoclays, denoted as Cu0/H20@NaMt and Ag0/H20@NaMt were further repeatedly washed with distilled water to eliminate the excess of Cu2+ and Ag+ cations and then dried overnight. Further, for the preparation of metal loaded H20@CT samples, 0.8g of AgNO3 or 1.24g of Cu(NO3)2 were each dissolved in 30 mL of distilled water and mixed with 1g and 1.5g of NaBH4, respectively in order to reduce Cu2+ and Ag+ into Cu0 and Ag0 nanoparticles (denoted as AgNPSand CuNPS,). This was achieved upon stirring for 5-6h at room temperature (RT), under nitrogen stream to prevent MNP oxidation. The resulting Ag0/H20@CT and Cu0/H20@CT samples were dried overnight at RT in a sealed enclosure containing dry O2-free nitrogen dried with NaOH pellets.