## 1 Introduction  
The stability of colloidal dispersions can be tuned by physisorption of surfactants or polymers onto their surface through soft interactions such as electrostatic interactions, hydrogen bonding, or van der Waals forces [1; 2; 3]. The occurrence of such associations results in the formation of complexes that have different properties from the original particles. In fact, the formation of these complexes can modify the interparticle interactions and their ability to adsorb at fluid-fluid interfaces [4; 5], which are very important issues for controlling the stability of thin films, emulsions, and foams [6; 7]. For example, silica nanoparticles are often extremely hydrophilic and tend to remain dispersed in the bulk, which limits their use in stabilizing emulsions or foams. However, the addition of molecules that can interact with their surface can help to improve their ability to adsorb at fluid-fluid interfaces [8; 9]. This has been demonstrated by several authors by using surfactants as modifiers, most of them interacting through electrostatic interactions [10; 11; 12; 13] or directly grafted through chemical bonds [14; 15].  
The enhanced adsorption capacity of modified nanoparticles at fluid-fluid interfaces, in contrast to bare particles, can be ascribed to the surface-active nature of the additives [8]. This effect is particularly noticeable when polymer-capped nanoparticles are used, as they are able to form highly stable emulsions, whereas both unmodified particles and the capping polymer do not exhibit suitable emulsifying properties in solution [14; 16]. However, the specific behavior of the polymer responsible for this enhanced efficacy is still poorly understood. Unlike unmodified nanoparticles, which have a limited capability to significantly reduce interfacial tension (at liquid-liquid interfaces) or surface tension (at liquid-vapor interfaces) through spontaneous adsorption from low-concentration suspensions, capped nanoparticles have the capacity to lower surface tension due to the presence of surface-active molecules bound to their surfaces. This drives the formation of a particle shell at the interface [14], which is relevant to various scientific fields, including physics, chemistry, and materials science; therefore, the motivation to study particle adsorption particles at fluid-fluid interfaces is multifaceted. First, interfacial adsorption plays a central role in several natural and industrial scenarios. In biological systems, the adsorption of proteins and surfactants on cell membranes affects cell function and communication. In industrial applications such as emulsions and foams, adsorption of particles at liquid interfaces affects stability, rheology, and overall product quality. In addition, the manipulation of interfacial adsorption has practical implications. Tailoring the adsorption of nanoparticles or molecules can lead to advanced materials with tunable properties, such as enhanced catalytic activity, improved drug delivery systems, and innovative sensors. This knowledge has the potential to revolutionize many industries, from healthcare to energy [16].  
This research aims to assess the effect of Pluronic F-127, a triblock copolymer composed of two poly(ethylene oxide) terminal segments and a central poly(propylene oxide) segment, on the modification of the adsorption capabilities of hydrophilic silica nanoparticles at water-vapor interfaces, as well as on the interfacial rheology of the formed layers. Several studies have shown that the presence of ether groups in the poly(ethylene oxide) blocks of Pluronic polymers favors their association with hydrophilic silica nanoparticles through hydrogen bonding [17; 18; 19], allowing for the preparation of decorated particles using a single-step adsorption methodology [20]. This provides an intriguing opportunity to exploit the physicochemical properties of silica nanoparticles, which have limited affinity for fluid-fluid interfaces, to manipulate and enhance the properties of such interfaces.