Multifaceted pH and Temperature Induced Self‐Assembly of P(DMAEMA‐co‐LMA)‐b‐POEGMA Terpolymers and Their Cationic Analogues in Aqueous Media

Abstract

This work focuses on the synthesis of novel amphiphilic block terpolymers of the type poly[(2‐(N,N‐dimethylamino) ethyl methacrylate)‐co‐(lauryl methacrylate)]‐b‐poly[(oligo ethylene glycol) methyl ether methacrylate] (P(DMAEMA‐co‐LMA)‐b‐POEGMA)) by reversible addition‐fragmentation chain transfer polymerization. The cationic amphiphilic polyelectrolyte analogs P(QDMAEMA‐co‐LMA)‐b‐POEGMA are obtained through quantitative quaternization of the DMAEMA segments. Molecular characterization by size exclusion chromatography, nuclear magnetic resonance, and Fourier Transform Infrared spectroscopies indicates the successful synthesis of these novel series of block terpolymers. The amine forms of the block copolymers respond to pH and temperature changes in aqueous solutions by forming unimolecular or multichain nanoaggregates of varying size, micropolarity, and internal structure, as indicated by light scattering and fluorescence spectroscopy techniques. At neutral and basic pH, the existence of micellar like nanoassemblies is observed in the solutions of P(DMAEMA‐co‐LMA)‐b‐POEGMA terpolymers, while aggregation into micellar‐like clusters take place at temperature values above room temperature due to the presence of the hydrophobic LMA segments. Unexpectedly, the cationic polyelectrolytes P(QDMAEMA‐co‐LMA)‐b‐POEGMA counterparts show temperature responsiveness as a consequence of the amphiphilicity of the polymeric system.

Multi-responsive poly(oligo(ethylene glycol)methyl methacrylate)-co-poly(2-(diisopropylamino)ethyl methacrylate) hyperbranched copolymers via reversible addition fragmentation chain transfer polymerization

“…CPAD was selected for its efficiency in RAFT polymerization of methacrylic monomers based on results from the literature. 47,48 EGDMA led to the development of the branched polymer chains introducing branching points.…”

Playing construction with the monomer toy box for the synthesis of multi‐stimuli responsive copolymers by reversible deactivation radical polymerization protocols

“…PDMAEMA is another important example of LCST‐polymer. Its cloud point can be adjusted from 25 to 80°C in pure water by changing molecular weight and pH 155–157 . UCST‐type copolymers are sparse in the scientific literature.…”

“…Such can be the case when the environmental stimulus triggers a switch from amphiphilic to double‐hydrophilic micelles. An example is provided by the dual‐responsive nanoaggregates obtained by Kafetzi and Pispas 157 with di‐block copolymers having a hydrophilic and thermoresponsive homopolymer (POEGMA) block and a P(DMAEMA‐ co ‐LMA) block. The latter is endowed with the permanently hydrophobic character of lauryl methacrylate (LMA) units and the hydrophobic/hydrophilic mixed character of DMAEMA segments, which is regulated by the pH and temperature.…”

Amphiphilic Random-Block Copolymer Micelles in Water: Precise and Dynamic Self-Assembly Controlled by Random Copolymer Association

“…51 Additionally, PEG-based micelles exhibit lower critical solution temperature (LCST)-type thermoresponsive solubility in water. 48−50,61−63 Therefore, we expected that if such random copolymers are installed as association segments into block copolymers, the resulting amphiphilic "random-block" copolymers 64,65 would form micelles characteristic of the random copolymer association as follows. (1) The size and aggregation number (N agg ) of micelles are controlled by the composition and DP of the random copolymer segments, respectively.…”