Kappa-carrageenan (κ-CRG) forms thermo-reversible physical hydrogels via a coil–helix transition and helix bundling, but its sulfate-driven electrostatic repulsion limits mechanical robustness and control over aqueous disintegration. Here, we show that plant-derived polyphenols reprogram κ-CRG gel through sulfate-directed binding in a structure-dependent manner. Tannic acid (TA) selectively engages κ-CRG sulfate groups, yielding transparent gels and a >5-fold increase in storage modulus, whereas the same TA triggers turbidity and precipitation in sulfate-free agarose, supporting sulfate-mediated specificity. Using monomeric pyrogallol as a galloyl analogue, we demonstrate that monovalent interactions partially reinforce κ-CRG but lack cooperative stabilization. Intervention timing further separates mechanism. Pyrogallol produces pathway-dependent mechanics and gelation temperature, while TA is stage-insensitive, consistent with multivalent network annealing. In simulated gastric/intestinal fluids, pyrogallol/κ-CRG gels retain morphology longer, whereas TA/κ-CRG ones disintegrate rapidly yet exhibit strong adhesion to rough substrates and human skin. These findings provide a fully food-grade route to tune κ-CRG mechanics, thermal behavior, adhesion and programmed disintegration.

Pluronic® F127 (Poloxamer 407) is a thermoresponsive triblock copolymer widely used for drug delivery and templating for porous materials, owing to its temperature‐dependent micellization and gelation in aqueous systems. While its self‐assembly behavior in water‐rich or low‐ethanol cosolvents (≤30%) is well established, the molecular behavior of F127 in near‐anhydrous ethanol (90%–100%) remains largely unexplored. Here, we report a reversed self‐assembly mechanism governed by the solubility and crystallinity of the hydrophilic poly(ethylene oxide) (PEO) blocks, rather than the hydrophobic PPO segments that drive micellization in water. F127 remains molecularly dissolved up to ~95% ethanol but undergoes precipitation above this threshold due to collapse of the dehydrated PEO chains. Upon heating, the precipitates reversibly dissolve through melting of PEO crystalline domains, a process confirmed by turbidity and dynamic light scattering analyses. Additionally, tannic acid (TA)—known to strongly hydrogen bond with PEO—modulates the precipitation and re‐dissolution kinetics. These findings highlight a fundamentally distinct assembly mechanism of F127 in ethanol‐rich environments, where solvent polarity and segmental solvation dominate. This study not only provides critical insight into the thermoresponsive behavior of amphiphilic polymers in poor solvents but also expands the potential utility of F127 in ethanol‐dominant drug formulations and soft‐material systems, particularly where aqueous conditions are undesirable.