2 research outputs found
Evaluation of bacterial strains for the induction of plant biochemicals, nutritional contents and isozymes in barley
Evaluation of bacterial strains for the induction of plant biochemicals, nutritional contents and isozymes in barley
The controlled placement of gold nanoparticles (AuNPs)
in polyÂ(styrene-<i>b</i>-isoprene-<i>b</i>-styrene)
[SIS] triblock copolymer
thin films was achieved by tuning the surface chemistry of the AuNPs.
Facile thiol ligand exchanges permitted quick and thorough exploration
of the surface chemistry effects on AuNP segregation behavior. By
using thiol-functionalized polystyrene (PS-SH) or 1-dodecanethiol
(C<sub>12</sub>SH) ligands to tune nanoparticle surface chemistry,
AuNPs were selectively incorporated into either the polystyrene (PS)
or the polyisoprene (PI) domains. Nanocomposite polymer films were
characterized by atomic force microscopy, transmission electron microscopy
(TEM), and TEM tomography. AuNPs synthesized with a C<sub>12</sub>SH capping ligand preferentially segregated into PI-rich domains.
However, after exchanging C<sub>12</sub>SH with PS-SH ligands to a
C<sub>12</sub>SH:PS-SH molar ratio of approximately 5:1, AuNPs showed
an affinity for PS-rich domains. The C<sub>12</sub>SH:PS-SH transition
ratio was much higher than expected, based on molecule-averaged surface
energy arguments that predicted a ratio of 0.4:1 to 0.8:1. The unexpected
transition ratio was rationalized according to the area-averaged enthalpic
contributions of the capping ligands. Furthermore, mixing and incorporating
PI- and PS-preferential AuNPs created a well-mixed nanocomposite,
which highlights the versatility of the AuNPs