Firstly, AgNO3 stock solution was
prepared by dissolving 4.724 g AgNO3 (63.5% of Ag) in 100 mL distilled
water boiling for 1 h, then the stock solution contains 0.03 g Ag per mL.
Secondly, to reduce AgNO3, 2 mL of the stock solution was dissolved
into 150 mL distilled water with 2 mL of 1% sodium citrate solution, and
the solutionwas kept boiling for 1 h. In this process, the sodium citrate solutionwas
used as an environment-friendly ‘green’ reducing agent (Rhim
et al., 2013).
The silver sol preparedwas greenish yellow.
And lastly, 3 g of
carrageenan and 0.9 g of glycerol were then dissolved into the silver sol
and heated for about 20 min at 95 °C with vigorous mixing using a magnetic
stirrer, cast onto the glass plate followed by the same procedures, as
described above.