RAFT dispersion polymerization of benzyl methacrylate in non-polar media using hydrogenated polybutadiene as a steric stabilizer block. Issue 47 (16th November 2020)

• Record Type: Journal Article
• Authors: Darmau, Bastien; Rymaruk, Matthew J.; Warren, Nicholas J.; Bening, Robert; Armes, Steven P.
• Is Part Of: Polymer chemistry. Volume 11:Issue 47(2020)
• Page Start: 7533
• Page End: 7541
• Publication Date: 2020-11-16
• Subjects: Polymers -- Periodicals; Macromolecules -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1039/d0py01371d
• Languages: English
• ISSNs: 1759-9954

Abstract

Abstract : Well-defined spheres, worms or vesicles are prepared via RAFT dispersion polymerization of benzyl methacrylate in n -dodecane at 90 °C using hydrogenated polybutadiene as a macro-RAFT agent. Abstract : A monohydroxy-capped hydrogenated polybutadiene (PhBD) is converted into a macromolecular chain transfer agent via esterification using a carboxylic acid-functionalized trithiocarbonate. 1 H NMR and UV spectroscopy studies indicated a mean degree of esterification of at least 95%. The resulting precursor is used for the reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate (BzMA) in n -dodecane at 90 °C. In principle, systematic variation of the mean degree of polymerization (DP) of the insoluble structure-directing PBzMA block should enable the formation of PhBD–PBzMA spheres, worms or vesicles via polymerization-induced self-assembly (PISA). In practice, only kinetically-trapped spheres are obtained when targeting DPs of up to 300 at 25% w/w solids. However, increasing the copolymer concentration up to 40% or 45% w/w provides access to well-defined worms or vesicles, respectively. Gel permeation chromatography and 1 H NMR spectroscopy studies confirmed relatively narrow molecular weight distributions ( M w / M n < 1.20) and high final BzMA conversions (≥99%), respectively. These diblock copolymer nano-objects were characterized in terms of their particle size and morphology using TEM and DLS and a phase diagram was constructed. According to rheology studies, the free-standing worm gels that are formed at ambient temperature have a critical gelation concentration of approximately 5.0% w/w.