Preparation of gold nanoparticles under presence of the diblock polyampholyte PMAA-b-PDMAEMA

The preparation of gold nanoparticles in presence of different weak polyampholytes is investigated. As diblock polyampholytes several poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), PMAA-b-PDMAEMA, have been used, characterized by different molecular weight and block ratio. HAuCl₄ is used as gold precursor where LiBH₄ is acting as reductive agent to obtain the gold nanoparticles. The addition of gold precursors to aqueous solutions of PMAA-b-PDMAEMA polyampholytes leads to an acidification of the solution resulting in a change of the polyampholyte conformation through protonation of the PDMAEMA blocks. This modification of polyampholyte conformation also allows the tuning of the size and size distribution of the accordingly formed gold nanoparticles. Investigations presented, are performed mainly by AFM of the systems in thin film adsorbed on native oxide-terminated Si substrate. TEM was used to reveal the change in size of the obtained gold nanoparticles.