Rational synthesis of epoxy-functional spheres, worms and vesicles by RAFT aqueous emulsion polymerisation of glycidyl methacrylate

• Published in: Polymer chemistry 2020-10, Vol.11 (39), p.6343-6355
• Main Authors: Hatton, Fiona L, Derry, Matthew J, Armes, Steven P
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Block copolymers; Chain transfer; Chemical synthesis; Cysteine; Degree of polymerization; Emulsion polymerization; Ethanol; Molecular weight distribution; Nucleation; Phase diagrams; Photon correlation spectroscopy; Polymer chemistry; Small angle X ray scattering; Solution polymerization; Vesicles; Worms
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/d0py01097a

The rational synthesis of epoxy-functional diblock copolymer nano-objects has been achieved via RAFT aqueous emulsion polymerisation of glycidyl methacrylate (GlyMA; aqueous solubility ∼22 g dm −3 at 50 °C) by utilising relatively mild conditions (pH 7, 50 °C) to preserve the epoxy groups. High monomer conversions were achieved within 1 h when using a poly(glycerol monomethacrylate) chain transfer agent with a mean degree of polymerisation (DP) of 28, with GPC analysis indicating relatively narrow molecular weight distributions ( M w / M n < 1.40) when targeting PGlyMA DPs up to 80. A phase diagram was constructed to identify the synthesis conditions required to access pure spheres, worms or vesicles. Transmission electron microscopy, dynamic light scattering and small-angle X-ray scattering (SAXS) studies indicated the formation of well-defined worms and vesicles when targeting relatively long PGlyMA blocks. These epoxy-functional nano-objects were derivatised via epoxy-thiol chemistry by reaction with l -cysteine in aqueous solution. Finally, an in situ SAXS study was conducted during the RAFT aqueous emulsion polymerisation of GlyMA at 50 °C to examine the nucleation and size evolution of PGMA 48 -PGlyMA 100 diblock copolymer spheres using a bespoke stirrable reaction cell. The rational synthesis of epoxy-functional diblock copolymer nano-objects has been achieved by RAFT aqueous emulsion polymerisation of glycidyl methacrylate under mild conditions (50 °C, pH 7) to preserve the epoxy groups.