https://nova.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:34874 Tue 03 Sep 2019 18:01:08 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:33528 Tue 03 Sep 2019 17:57:15 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:29256 a. Furthermore, the simulations reveal that the addition of a single Flory-Huggins interaction parameter analogous to the hydrophilicity of the counterion is sufficient to replicate the observed specific anion response of a hydrophobic weak polyelectrolyte brush.]]> Sat 24 Mar 2018 07:39:15 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:48241 Sat 11 Mar 2023 12:51:24 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:40383 2MA), a thermoresponsive polymer with a lower critical solution temperature of ~28 ℃, and poly(2-(diethylamino)ethyl methacrylate) (PDEA), a weak polybase with an apparent pKa of ~7.5, have been statistically copolymerized using activators continuously regenerated via electron transfer atom transfer radical polymerization to form multi-stimulus-responsive polymer brushes. The stimulus-responsive behavior of these brushes has been investigated with ellipsometry and numerical self-consistent field (nSCF) theory. The pH- and thermoresponsive behaviors of a PDEA homopolymer brush were investigated experimentally in order to benchmark the nSCF theory calculations. nSCF theory was able to reproduce the responsive behavior of PDEA and PMEO₂MA homopolymer brushes. Three copolymer compositions (90:10, 70:30, and 50:50 mol % MEO₂MA:DEA) were investigated experimentally with pH ramps performed at low and high temperatures and temperature ramps performed at low and high pH. A broader range of compositions were investigated with nSCF theory and compared to the experimental results, with the nSCF calculations able to capture the general behavior of the homopolymer and copolymer brushes. The responsive behavior of each brush to a given stimulus (temperature or pH) was dependent on both the polymer composition and environment (temperature or pH). The influence of pH on the brush increased with higher DEA mol % with a copolymer brush response transitioning from temperature-dominant to pH-dominant. The temperature response of PMEO₂MA was completely masked at low and high pH values by the presence of at least 30 mol % polybase in the copolymer.]]> Mon 11 Jul 2022 11:00:49 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:44487 co-2-(diethylamino)ethyl methacrylate) [P(MEO₂MA-co-DEA)] 80:20 mol % copolymer brushes were synthesized on planar silica substrates via surface-initiated activators continuously regenerated via electron transfer atom transfer radical polymerization. Brush thickness was sensitive to changes in pH and temperature as monitored with ellipsometry. At low pH, the brush is charged and swollen, while at high pH, the brush is uncharged and more collapsed. Clear thermoresponsive behavior is also observed with the brush more swollen at low temperatures compared to high temperatures at both high and low pH. Neutron reflectometry was used to determine the polymer volume fraction profiles (VFPs) at various pH values and temperatures. A region of lower polymer content, or a depletion region, near the substrate is present in all of the experimental polymer VFPs, and it is more pronounced at low pH (high charge) and less so at high pH (low charge). Polymer VFPs calculated through numerical self-consistent field theory suggest that enrichment of DEA monomers near the substrate results in the experimentally observed non-monotonic VFPs. Adsorption of DEA monomers to the substrate prior to initiation of polymerization could give rise to DEA segment-enriched region proximal to the substrate.]]> Fri 14 Oct 2022 08:57:26 AEDT ]]>