Abstract:
This research was aimed to study the preparations of polymer nanocomposites of natural rubber with poly [styrene-co-2-(methacryloyloxy) ethyl trimethylammonium chloride] (P(S-QDM)) nanoparticle as an organic material and silver nanoparticle as an inorganic material in the emulsion systems, using heterocoagulation technique with the electrostatic interaction.
In the case of natural rubber (NR) and P(S-QDM) blending, P(S-QDM) nanoparticle was firstly prepared by emulsion polymerization. The diameter of the prepared nanoparticle was 75.80 nm whereas the charge on its surface represented +52.10 mV. Thereafter, the pH of NR latex (NRL) emulsion was adjusted to the acidic conditions to obtain the positive charge on the NRL surface. It was found that pH of 2 was the optimal condition. In the blending process, the amount of polymer nanoparticle at various ratios was studied. The optimal amount of polymer nanoparticle was Nmax (the maximum number of polymer nanoparticles completely enveloped NRL). The polymer nanoparticle emulsion (pH of 2) having positive surface charge was added into the NRL emulsion (pH of 2) having the same positive charge. Thereafter, pH of the blending emulsion was gradually increased to 8 in which NRL represented the negative surface charge and then coalesced with positive charge P(S-QDM) nanoparticle. The obtained polymer nanocomposite size (228.70
nm) increased from those of the original NR (142.30 nm) and P(S-QDM). Moreover, the positive charge of 23.60 mV was presented on the polymer nanocomposite surface. After film casting and the tensile strength testing, the strength of the nanocomposite film was enhanced, compared with the NR host film. In the case of NR and silver nanoparticle blending, silver nanoparticle was firstly prepared by the chemical reduction method resulting in a clear yellow solution. Thereafter, the silver nanoparticle dispersed in water was firstly coated with Tween 80 and then hexadecyl trimethyl ammonium bromide forming positive charge silver nanoparticle with 50.33 mV. After blending with NRL using the same condition as NRL and P(S-QDM) blending, the distribution of silver nanoparticle in the composite film was observed. The composite film was found to be effective in inhibiting bacteria both Staphylococcus aureus and Escherichia coli.
It could be concluded that the nanocomposites of NRL with an organic and an inorganic materials were successfully prepared by the heterocoagulation technique with the electrostatic interaction in the appropriate condition without the utilization of organic solvent. The tensile strengths of NR/P(S-QDM) films were improved from the host NR film. Moreover, the polymer nanocomposite film of NRL and silver nanoparticle could effectively inhibit bacteria and it could be applied in medical treatment.