Confinement-Induced Growth of Gold Nanocrystals in Hybrid Hierarchical Polymer Nanowire

The growth of metal nanocrystals within polymer nanowiresdeviates from the conventional nucleation-growth process asmovements of nucleated metal nanocrystals are hindered due tosimultaneous growth of the polymer. We have carried out systematic insitu small-angle and diffraction measurements simultaneously duringgrowth of gold-polypyrrole composite nanowire within membranes anddeveloped a method to extract the shape and size of gold nanocrystals tounderstand the growth mechanism. Our results give unique informationregarding the early growth processes of nanocrystals as a function of thepore diameter of membranes and concentration of HAuCl4 solution usedfor the polymerization reaction. We have shown that gold nanocrystalsfirst grow along the [111] direction through contact epitaxy as acylindrically shaped nanocrystal and then get transformed into nearsphericalnanocrystals. The synchrotron X-ray scattering techniquepresented here can be used to study similar growth processes