As seen above, PVA or CS microphase separation is actively induced through a temperature change or soaking. In contrast, the formation of nano-sized micelles can occur spontaneously and has paved the way towards energydissipating tough hydrogels via reversible micelle aggregation upon the application of stress (Figure ). Most commonly, aliphatic monomers, such as stearyl (meth)acrylate (SMA/SA) or lauryl methacrylate (LMA) are combined with a surfactant (e.g., sodium dodecyl sulfate (SDS) or cetyltrimethylammonium bromide (CTAB)) in a preassembly stage. The formed micelles are complemented by hydrophilic monomers in the surrounding aqueous solution, which later form the bulk network. Reported tough hydrogels involve P(AAm-stat-SMA)/SDS, P(AAcstat-SA)/CTAB, P(AAc-stat-LMA)/CTAB, among others. One notable example was published by Liu and co- workers, who polymerized CTAB-stabilized, SA-containing micelles in the presence of an aqueous MAAc-rich bulk phase to obtain a first network. Immersion of this first network in a solution of AAm followed by photopolymerization produced a tough SIPN. The system was shown to be widely tunable, as can be witnessed by the two datapoints we report, with one gel exhibiting a water content of 90%, the other 54%. The reduction of the water content (resulting from an increase in CTAB concentration) improved all four key mechanical properties: Stiffness (E = 1.31 to 9.25 MPa), fracture toughness (Γ = 0.6 to 14.6 kJ/m 2 ), fracture stress (σ b = 1.32 to 2.73 MPa) and fracture strain (ε b = 717 to 1149%), certainly representing a rare occurence. When the hydrophobe-to-surfactant ratio is sufficiently high, a micellar solution can transition to an oil-in-water emulsion. In a fitting example, a methacrylate-telechelic, amphiphilic PU was used as reactive emulsifier to stabilize oil droplets that contained acrylonitrile (AN) in the presence of an aqueous, AAm-rich bulk phase. Upon polymer-ization, a dual cross-linked network was obtained with a covalent AAm network and hydrophobic spherical aggregates (120 nm) made from PAN as physical cross-links. The tough hydrogel shows high fracture energy (Γ = 37.2 kJ/m 2 ) and fracture strength (σ b = 24.7 MPa), yet the stiffness reaches only E = 76 kPa. Further to this, the bespoke gel sample is closer to the nature of an elastomer, since its water content is as low as 23%.