Hydrophobically Functionalized Poly(Acrylic Acid) Comprising the Ester-Type Labile Spacer: Synthesis and Self-Organization in Water

Abstract

One of the most important properties of hydrophobically functionalized polyelectrolytes (HF-PEs) and their assemblies is their ability to encapsulate hydrophobic/amphiphilic agents and provide release on demand of the entrapped payload. The aim of the present work was to synthesize and study self-organization behavior in aqueous solution of hydrophobically functionalized poly(acrylic acid) (PAA) comprising the ester-type pH labile moiety with various degrees of hydrophobization and side-chain lengths in the absence and presence of appropriate mono- and polyvalent electrolytes (i.e., NaCl or CaCl2). The synthesis and purification of hydrophobically functionalized PAA were performed under mild conditions in order to avoid chemical degradation of the polymers. The modified polyelectrolytes self-assembly in aqueous systems was monitored using diffusion-ordered nuclear magnetic resonance (DOSY NMR). The performed studies, supported by the all-atoms molecular dynamics simulations, revealed a strong dependence of polyelectrolyte self-assembled state on concentration—specific concentration regions with the coexistence of both smaller and larger aggregates were observed (values of hydrodynamic diameter DH around one nanometer and between two to six nanometers, respectively). Our investigations enabled us to gain crucial information about the self-assembly of the hydrophobically functionalized poly(acrylic acid) and opened the possibility of understanding and predicting its performance under various conditions.

Rational Mitomycin Nanocarriers Based on Hydrophobically Functionalized Polyelectrolytes and Poly(lactide-co-glycolide)

“…1–2 nm) were found to be present for broad concentration ranges, but their dimensions were insufficient for measurable values of the zeta potential and observable electrostatic interactions. 23 , 24 Conversely, the aforementioned functionalized polyelectrolytes were found to efficiently adsorb at hydrophobic/hydrophilic interfaces, leading to their stabilization via electrostatic repulsion. The higher value of the optimal concentration for PAA- g -C 12 OH (40%) in comparison to that of other HF-PEs is connected to its lowest HLB (see Table 1 )—the aforementioned compound is too hydrophobic and thus cannot sufficiently stabilize nanoparticles via electrostatic repulsive forces at low concentrations.…”

“…Moreover, in contrast to nonhydrophobically functionalized polyelectrolytes, as well as low-molecular-weight surfactants, our derivatives might effectively stabilize nanoparticles even at very low concentrations. 23 , 24 …”

Multilayered Curcumin-loaded Hydrogel Microcarriers With Antimicrobial Function

“…Moreover, a weaker signal (4.5 times by integration intensity, chemical shift 3.6 ppm) attributed to the methylene moiety directly bonded to the quaternary ammonium moiety was identified. Signals attributed to the repeating methylene and methine groups in the polyelectrolyte backbone, as well as repeating methylene moieties in the side chains, appeared as broad signals in the region of 1.1 -2.4 ppm [19]. It was impossible to assign the mentioned signals directly due to their overlap.…”

“…Alkylene quaternary ammonium salt decorated PAA was prepared in a two-step reaction (Scheme I). In the first step, poly(acrylic acid) modified with a bromine-terminated hydrophobic chain was synthesised under mild conditions by Steglich esterification with N,N-dicyclohexylcarbodiimide (DCC) as a coupling agent and 4-dimethylaminopyridine (DMAP) as a catalyst [19,20]. Subsequently, bromine-terminated poly (acrylic acid) was converted to a quaternary ammonium salt by quaternisation with trimethylamine.…”

“…In general, polyelectrolyte functionalisation, especially through decoration with short side groups, leads to obtaining products with a random structure [15]. This strategy often involves steps under mild conditions, such as Steglich esterification or amidation, to avoid degradation of the backbone [19,20]. Polyelectrolytes with hydrophilic/hydrophobic side chains of various lengths with a suitable active moiety (e.g.…”