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.