Oral Presentation Royal Australian Chemical Institute National Congress 2026

Waterborne multiblock copolymer nanocomposite films with enhanced mechanical properties via MacroRAFT emulsion polymerization. (138608)

Seyed Ahmad Ayati Najafabadi 1 , Steven W. Thompson 1 , Per B. Zetterlund 1
  1. Cluster for Advanced Macromolecular Design (CAMD),School of Chemical Engineering, The University of New South Wales (UNSW Sydney), Sydney, NSW, Australia

Recent advances in the film formation of emulsion copolymers have focused on the use of nanoengineered latex particles composed of multiblock copolymers (MBCPs), synthesized via reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization. These MBCP nanoparticles can overcome the film formation dilemma and produce films with excellent mechanical properties.1 Within the nanoparticles, microphase separation occurs between chemically incompatible polymer blocks: polystyrene (Tg ~ 100 °C), which provides mechanical strength, and poly(n-butyl acrylate) (Tg ~ −54 °C), which enhances film-forming ability.2, 3 Such nanocomposite films with 2D inorganic fillers exhibit excellent tensile strength. Siloxene is a 2D low-buckling structured silicon network with unique properties, and MBCP nanocomposite films containing only a small amount of exfoliated siloxene content as 2D inorganic fillers, homogeneously dispersed in the matrix, show excellent mechanical performance.4

Figure. 1: MacroRAFT emulsion polymerization for MBCP latex synthesis, followed by MBCP/siloxene nanocomposite film formation.

A critical step in the synthesis of well-defined MBCPs is the RAFT emulsion polymerization of the initial seed latex, which is strongly influenced by the structure of the amphiphilic macroRAFT agent. In this study, the effect of hydrophilic and hydrophobic block lengths of poly(methacrylic acid-b-methyl methacrylate) macroRAFT agents on latex nanoparticle properties (including colloidal stability, morphology, and viscosity) was systematically investigated. The optimized poly(n-butyl acrylate) nanoparticles were subsequently chain-extended with styrene and n-butyl acrylate to produce high molecular weight MBCP particles. These particles were physically mixed with an aqueous siloxene dispersion and converted into nanocomposite films via direct latex casting (Fig. 1). The results demonstrate that the macroRAFT structure plays a key role in controlling RAFT emulsion polymerization, enabling the preparation of well-defined MBCP films with a high styrene content (~ 62 wt%) but yet soft. MBCP/siloxene nanocomposite film exhibited excellent mechanical performance with the addition of very low levels of siloxene sheets (nanofiller), a promising material for advanced applications.

  1. Clothier, G. K.; Guimarães, T. R.;  Thompson, S. W.;  Rho, J. Y.;  Perrier, S.;  Moad, G.; Zetterlund, P. B., Multiblock copolymer synthesis via RAFT emulsion polymerization. Chemical Society Reviews 2023, 52 (10), 3438-3469.
  2. Thompson, S. W.; Guimarães, T. R.; Zetterlund, P. B., Sequence-Defined Multiblock Copolymer Nanoengineered Particles from Polymerization-Induced Self-Assembly (PISA): Synthesis and Film Formation. Macromolecules 2023, 56 (23), 9711-9724.
  3. Aguirre, M.; Ballard, N.;  Gonzalez, E.;  Hamzehlou, S.;  Sardon, H.;  Calderon, M.;  Paulis, M.;  Tomovska, R.;  Dupin, D.; Bean, R. H., Polymer colloids: current challenges, emerging applications, and new developments. Macromolecules 2023, 56 (7), 2579-2607.
  4. Yan, X.; Fang, L.;  Zhang, H.;  Yang, J.; Yoon, K. B., Preparation of polyethylene/Siloxene nanocomposites through siloxene‐MgCl supported Ziegler‐Natta catalyst. Polymer Composites 2024, 45 (13), 11975-11984.