2.2. Synthesis procedure
Synthesis of Ag+-Mt was carried out by intercalation and ionexchange
reaction of AgNO3with Na salt ofMt in aqueousmedium. Approximate
amounts of AgNO3 and Na+-Mt are separately dissolved and
dispersed in double distilledwater to prepare solutions at 0.4 and 0.1 g/
mL concentrations, respectively. Then 10 mL of silver nitrate solution is
added to Na+-Mt dispersion drop by drop by stirring at 40 °C for 3 h up
to turn of reaction solution to yellow. The light yellow water solution of
Ag+-Mt indicates the formation of intercalated silver nanoparticles
(Kulkarni, 2009), which was also confirmed by UV and XRD analyses.
After cooling the reactionmixture up to roomtemperature, Ag+-Mt (intercalated
via ion-exchange interaction) was isolated by precipitation
with methanol and extraction–centrifugation. The prepared steel gray
powder product undergoes a treatment at 150 °C for 5min under nitrogen
flow and dried under vacuum at 80 °C to fully in situ generation of
the intercalated AgNO3 cations to silver nanoparticles (AgNPs). After
this thermal treatment, the formation of light-brown powder product
as a result of in situ generation processing confirmed significantly
riching Mt clay with intercalated AgNPs. This method (annealing or
UV-irradiation) is well known and widely used for the fabrication of
AgNPs in various polymer nanocomposites.
Synthesis of copolymer-g-PLA layered silicate CNPs includes the following
steps: (1) 3.5 g of copolymerwas dissolved in 20mLLA by intensive
mixing at 40 °C up to the formation a homogeneous viscous
product; (2) 0.175 g of any clay (Na+-Mt, Ag+-Mt or ODA-Mt as
catalyst-nanofillers) was dissolved in 5 mL LA by intensive mixing at
room temperature for 6 h up to fully intercalation of LA monomer between
silicate interlayer species, and (3) both solutions of copolymer
and inorganic or organic clays, were placed in a specially constructed
vacuum (600 mm/Hg) micro-reactor with Dean-Stark unit and mixed
at 80 °C up to previously fixed phase separation time for each clay
around 25–56 min (for ODA-Mt 56 min, Na+-Mt 35 min and Ag+-Mt
25 min). Then, powder polymer particles were isolated from the reaction
mixture by precipitationwithmethanol, twice extraction–ultracentrifugation
and dried under vacuum at 40 °C.