Self-assembly of polyelectrolyte diblock copolymers at monovalent and multivalent counterions

Abstract

One and two dimensional macroscopic aggregation of micelles occurs in the presence of multivalent counterions.

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

“…Chemical structures were assessed by 1 H NMR, recorded on a Bruker AMX-500 instrument. The chemical shifts in 1 H NMR spectra are referenced to deuterium hydrogen oxide (semiheavy water, HDO) residual signal as an internal standard. The prepared grafted polyelectrolytes were dissolved in D 2 O before analysis.…”

“…Due to their unique self-assembly properties, amphiphilic polymers constitute valuable specialty products, yielding nanocarriers for biomedical purposes, engineered surfaces as well as viscosity modifiers for various applications. The aggregate morphologies of non-charged copolymers are controlled by thermodynamic equilibrium: a balance between interfacial tension and chain stretching energies [1]. On the other hand, charged amphiphilic polymers, i.e., hydrophobically functionalized polyelectrolytes (HF-PEs), may be divided into two general groups: amphiphilic polyelectrolytes with ionizable groups, separated by hydrophobic units (like hexamethylene), comprising alternating hydrophilic/hydrophobic linear structures [2] (diblock copolymers with hydrophilic and hydrophobic blocks being a special case) and hydrophobically modified polyelectrolytes composed of polyelectrolyte (PE) backbone with hydrophobic side groups, such as shorter or longer alkyl chains, aromatic rings, etc.…”

“…The most important feature of HF-PEs is their ability to self-assemble into a number of stimuli-responsive morphologies, which may undergo phase transitions or perform a release of solubilized/entrapped payload upon minor changes in temperature, pH, ionic strength, or by external physical stimuli (e.g., electric and magnetic fields) [4,5]. The above-mentioned specialty polymers may play a role as responsive aggregates for various applications, e.g., from drug and gene delivery to tissue engineering and battery electrolyte materials [1,6,7]. For functionalized polymers comprising PE backbone with hydrophobic side groups, the pH-responsivity is connected with protonation/deprotonation of weak or moderate electrolyte groups as well as hydrolysis of labile bonds between backbone and side chains.…”

“…An additional point of interest concerns the presence of an appropriate linking group between the fragments of extreme hydrophobicity-preferably a hydrolysable moiety like ester, secondary or tertiary amide, acetale, carbamate or urea-in order to attain sufficient biodegradability and reduced toxicity to higher organisms. The linker group may also contribute an added value to responsivities of HF-PEs to stimuli, due to its influence on weak interactions within the polyelectrolyte backbone [1][2][3][4][5]. The use of pH-sensitive polymers in drug delivery systems (DDSs) enables targeted payload release, which increases treatment efficiency as well as minimizing side effects.…”

Micellization through complexation of oppositely charged diblock copolymers: Effects of composition, polymer architecture, salt of different valency, and thermoresponsive block

“…In recent years there is an increased interest in micelles formed from the mixing of oppositely charged ionicneutral double hydrophilic diblock copolymers in aqueous solutions [1][2][3][4][5][6][7][8][9] since they are promising candidates for a variety of applications. The formed polyelectrolyte complex micelles (PCMs) are potential carriers of charged compounds such as DNA, 10 RNA, 11 nanoparticles, 12 and metal ions, 13 and can be used in wastewater treatment by flocculating charged pollutants.…”