Mechanical properties of nanostructured films with an ultralow volume fraction of hard phase

Abstract

We demonstrate in this paper how polymerization induced self-assembly (PISA) using RAFT can be used to synthesize very asymmetric but monodisperse poly(acrylic acid)-b-poly(nbutyl acrylate) block copolymers, PAA-b-PBA, with a short PAA block and a long PBA block. In the course of the surfactant-free emulsion polymerization, core-shell particles form in water, with the short hydrophilic block located at the water-particle interface, and the long hydrophobic block constituting the particle core. Drying at room temperature creates films possessing an out of equilibrium structure, where the glassy PAA block generates a percolating network of shells. When deformed in uniaxial elongation, these films combine a high stiffness in small strains (considering the low volume fraction of PAA, of only 3 wt%), a yield stress and a significant extensibility before failure. The modulus, yield stress and extensibility can be tuned by modifying the composition of the latex serum with cations or positively charged low molar mass polymers, or by changing the copolymer composition. Of particular interest was the synthesis by PISA of particles of triblock copolymer PAA-b-PBAb-PS. The out of equilibrium structure obtained had a very interesting combination of high stiffness, extensibility and high fracture toughness.

Water-based acrylic coatings reinforced by PISA-derived fibers

“…11 In particular, we reported recently how one can take advantage of the current developments in polymerization-induced self-assembly (PISA) to prepare nanostructured latex-based films combining high stiffness and high deformability, seemingly contradictory properties. 12,13 The materials were exclusively made of spherical soft-core/hard-shell particles, constituted of highly asymmetric poly(acrylic acid)-b-poly(n-butyl acrylate), PAA-b-PBA, block copolymers, synthesized in water thanks to a RAFT emulsion polymerization process. 14 The enhanced stiffness of the materials at low strain was attributed to the percolating network formed by the glassy PAA shells.…”

Synthesis of Film‐Forming Photoactive Latex Particles by Emulsion Polymerization–Induced Self‐Assembly to Produce Singlet Oxygen

“…More recently, Chenal et al. interestingly showed that poly(acrylic acid)‐ b ‐poly( n ‐butyl acrylate) (PAA‐ b ‐P n BA) synthesized by emulsion PISA produced homogeneous and cohesive transparent polymer films . The percolating network of the thin high glass transition temperature ( T g ) layer at low volume fraction was at the origin of these remarkable mechanical properties of the low T g polymer film.…”

“…[6] Singlet oxygen, a powerful oxidant produced by energy transfer from the photoactivated sensitizer to (PAA-b-PnBA) synthesized by emulsion PISA produced homogeneous and cohesive transparent polymer films. [24,25] The percolating network of the thin high glass transition temperature (T g ) layer at low volume fraction was at the origin of these remarkable mechanical properties of the low T g polymer film. Another study showed that the adsorption of PAA-b-PnBA diblock copolymer onto soft acrylic latex particles prior to their film formation also creates a percolating network that raises the elastic modulus, creep resistance, and tensile strength of the final film.…”

Controlling Nanomaterial Size and Shape for Biomedical Applications via Polymerization‐Induced Self‐Assembly

“…Both the size and shape of nanoparticles are crucial factors that impact their properties and applications. [15][16][17][18][19] For instance, the size and shape of PISA nanoparticles have been found to significantly affect their in vivo biodistribution. [20] Although many applications have been proposed for PISA nano-objects including lubricants, pigment encapsulation, catalysis systems, coatings, and Pickering emulsifiers, their use in biomedical science is arguably the most exciting.…”

“…Both the size and shape of nanoparticles are crucial factors that impact their properties and applications . For instance, the size and shape of PISA nanoparticles have been found to significantly affect their in vivo biodistribution .…”