Insight into the Origin of the Thermosensitivity of Poly[2‐(dimethylamino)ethyl methacrylate]

Abstract

We investigate the effects of pH and temperature on the conformational changes of poly[2-(dimethylamino)ethyl methacrylate] (PDEM) chains at the air/water interface by using Langmuir balance and sum frequency generation vibrational spectroscopy. At pH 4, the tertiary amine groups are fully charged and the PDEM chains are so hydrophilic that they completely enter into the water phase and do not exhibit thermosensitivity. At pH 7, these groups are only partially charged, and the accompanying hydration/dehydration--followed by repartitioning into the water and air phases--gives rise to a marked thermosensitivty. Finally, at pH 10, the tertiary amine groups become uncharged and thus preferentially stay in the hydrophobic air phase, devoid of associated water molecules, which results in the surface-pressure change (DeltaPi) being nearly independent of the temperature. Our Langmuir-balance experiments, coupled with surface-sensitive spectroscopy, demonstrate that: 1) the thermosensitivity of the PDEM chains relates to the hydration/dehydration of the tertiary amine groups, 2) the phase transition of thermosensitive polymers is most likely initiated by the dehydration of the chains, and 3) the phase transition of thermosensitive polymers at the air/water interface is markedly different from that in aqueous solution because of the redistribution of the macromolecular segments induced by the asymmetric forces at the air/water interface.

Charged hydrophilic polymer brushes and their relevance for understanding marine biofouling

“…These charged polymers are compared to neutral PHEMA-co-PEG10MA (poly(2-hydroxyethyl methacrylate-co-polyethylene glycol methacrylate)) and zwitterionic PSBMA (poly((sulfobetaine methacrylate)), materials which are well studied in the context of marine fouling, and which also have shown good antifouling properties (Ekblad et al 2008, Yandi et al 2014, Zhang et al 2009). PDMAEMA is a pH-and temperaturesensitive material due to the presence of hydrophilic amino groups, and hydrophobic segments at the end of the side chains (Liu et al 2007). In acidic solution, PDMAEMA is hydrophilic and fully ionized by protonation of the ammonium, and it interacts strongly with surrounding water molecules.…”

“…However, as the pH increases this interaction is gradually weakened due to decreasing protonation of ammonium groups, resulting in a heterogeneous structure with partial loss of hydration and thus also amphiphilic behavior. This polymer has antimicrobial properties against both Gram-positive and Gram-negative bacteria (Lee et al 2004, Liu et al 2007, Rawlinson et al 2010. The anionic PSPMA has also been reported to reduce bacterial adhesion and to inhibit the growth of bacteria due to high surface hydration resulting from solvation of the sulfonate groups (Guo et al 2013, Ramstedt et al 2007, and also result in lower attachment of E. coli and delayed growth of biofilm in membrane filtration tests (Wibisono et al 2015).…”

Antibacterial Effects of Poly(2-(dimethylamino ethyl)methacrylate) against Selected Gram-Positive and Gram-Negative Bacteria

“…The solubility of pDMAEMA in aqueous solution is also pH-dependent. At pH 7, pDMAEMA is partially charged (hydrophilic) and partially uncharged (hydrophobic), resulting in an amphiphilic molecule 19 . At lower pH the polymer becomes more positively charged and at pH values greater than 7 it becomes mostly uncharged 19 .…”

Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: A novel platform for eco-friendly biofouling mitigation

“…Poly ethylene glycol (PEG) based coating materials are well known for their remarkable antifouling properties (Ekblad et al 2008). Cationic polyDMAEMA has also been reported as a potential antimicrobial material (Liu et al 2007), as has the anionic counterpart polySPMA (Wan et al 2012).…”