Surfactant-free synthesis of amphiphilic diblock copolymer nanoparticles via nitroxide-mediated emulsion polymerization

Abstract

Amphiphilic hairy nanoparticles are prepared in a one step, batch, heterogeneous polymerization of styrene or n-butyl acrylate, using a water-soluble poly(sodium acrylate) alkoxyamine macroinitiator based on the SG1 nitroxide.

Nitroxide‐Mediated Aqueous Dispersion Polymerization: From Water‐Soluble Macroalkoxyamine to Thermosensitive Nanogels

“…When temperature was increased above the critical temperature, the copolymer chains self-assembled again into a viscous dispersion, but the particles exhibited a diameter significantly larger than the original ones, certainly because the characteristics of the copolymer chains were no longer the same as when particles initially formed during the polymerization step. [13] At low T and low pH, they formed ''inverse'' particles with a hydrophobic PAA core and a hydrophilic PDEAAm shell, whereas precipitation occurred at low pH and high T (see Figure 1). Such solubility results are analogous to those reported by André et al for PAA-b-PDEAAm prepared by anionic polymerization.…”

“…A similar route was applied in the past for the emulsion polymerization of styrene and butyl acrylate leading to the in situ formation of amphiphilic diblock copolymer nanoparticles analogous to crew-cut micelles. [13] In a first step, a short PAA block with an alkoxyamine reactive end-group was synthesized by the direct polymerization of acrylic acid in 1,4-dioxane using the nitroxide SG1 as a mediator. Synthesis of the macroinitiator and chain-end characterization have been previously described in detail.…”

Recent advances in controlled/living radical polymerization in emulsion and dispersion

“…As a consequence, their sizes were varied upon a change in pH of dispersions, ranging from 65 nm for PS particles and 90 nm for PBA particles at pH ¼ 7 to 55 nm for PS and 76 nm for PBA at pH ¼ 4. 205 For RAFT emulsion polymerization, a water-soluble macroRAFT agent was prepared by RAFT polymerization of N,N-(diethylamino)ethyl methacrylate (DEAEMA) in the presence of CPDB RAFT agent in EtOH at 60 C. After purification in acetone under alkali conditions, CPDB-terminated P(DEAEMA-H þ Cl À ) with narrow M w /M n ¼ 1.3 was used as macroRAFT agents for surfactant-free batch emulsion polymerization of St at 70 C. Monomer conversion was completed within 3 h, producing a stable latex particle with a diameter of 95-112 nm. The conversion versus time plot suggested that the nucleation mechanism involves the reaction of water-soluble oligoradicals with macroRAFT agents, leading to the formation of amphiphilic block copolymers as stabilizers in batch emulsion polymerization.…”

Block copolymer synthesis by controlled/living radical polymerisation in heterogeneous systems

“…17 Several recent papers report successful results using a batch process with amphiphilic macro-RAFT agents formed in situ in the presence of monomer droplets. [63][64][65][66] In particular, the development of systems where the nucleation step is based on self-assembly of block copolymers [67][68][69][70][71] require no low molecular weight surfactant, as that function is fulfilled by the amphiphilic block copolymer.…”

“…[220][221][222] Amphiphilic block copolymers PAA-b-PSt or PAA-b-P n BuA were prepared in water using a PNaA-SG1 at 120 °C. A stable emulsion of spherical nanoparticles was obtained through PISA as the hydrophobic block grew.…”