Atilla C. Varga

3D printed acrylonitrile butadiene styrene (ABS) and polyvinyl alcohol (PVA) structures were infiltrated by alumina (Al2O3) using a trimethylaluminum(III) and water ALD process at 130 and 80 °C, respectively, to alter their physical properties. Differential scanning calorimetry was used to determine the glass transition temperature (Tg) of the polymers’ pre- and post-deposition after varying the number of ALD cycles, resulting in a change of ∼9 and ∼ 27 °C for ABS and PVA, respectively. After one heat cycle, the postdeposition Tg reverted back to its predisposition point indicating reversibility of the deposition effects are possible. Optimal growing patterns, polymer composition, and inhibiting surface coatings—seen by energy-dispersive x-ray spectroscopy mapping—affected the amount of infiltration possible within the polymer substrate and, in turn, Tg. The results achieved provide guidelines to altering the physical and thermal properties of 3D printed polymer architectures.

Group 11 thin films are desirable as interconnects in microelectronics. Although many M–N bonded Cu precursors have been explored for vapor deposition, there is currently a lack of suitable Ag and Au derivatives. Herein, we present monovalent Cu, Ag and Au 1,3-di-tert-butyltriazenides that have potential for use in vapor deposition. These compounds possess thermal stability and volatility that rival that of current state-of-the-art group 11 precursors with bidentate M–N bonded ligands. All compound sublime quantitatively between 120 and 130 °C at 0.5 mbar. Thermogravimetric analysis showed the Cu and Ag compounds both volatilized at  200 °C with 0 and 2% residual mass, respectively. The Au triazenide showed two separated mass loss events at  175 and 240 °C, and 35% residual mass. The crystal structure of the Cu compound showed a dimer, whilst the Ag and Au derivatives were tetrameric. Nuclear magnetic resonance spectroscopy showed dimers for the Cu and Au compounds and a dimer/tetramer equilibrium for the Ag compound. Electronic energies from density functional theory calculations confirmed dimeric preference for the Cu triazenide while Ag and Au preferred the tetrameric. However, all three compounds showed dimeric preference when accounting for entropy. Dimers are, therefore, expected to dominate in the gas phase for all three compounds during sublimation. Natural bond orbital analysis was used to identify orbital interactions important for the dimer/tetramer preference. Three factors were identified, in conjunction with strong metal-metal interactions, to increase the preference for rhombic tetramers.