Coacervates, recognized as versatile soft matter assemblies, play a critical role at the forefront of diverse area, ranging from food technology innovations to cutting-edge pharmaceutical application and proto-cell investigation [[1], [2], [3], [4], [5]]. These complex assemblies, forming condensed liquid-like droplets, is primarily driven by the entropy gain through the interaction between polymers, e.g. electrostatic interactions, π-π conjugation, hydrogen bonding or hydrophobic interaction [[6], [7], [8]]. Recently, it has emerged as promising candidates for adhesive application, catering to needs in drug delivery systems, wound care, etc [9,10]. Despite their potential, fully leveraging the inherent adhesive properties of coacervates remains a significant challenge. This gap in application and optimization has spurred ongoing research to explore novel methods for enhancing their adhesive properties [11].

Recent advancements in the field have introduced various approaches to enhance the adhesive properties of coacervates, expanding from tuning charge interactions to incorporating novel chemical functionalities, such as coacervate-to-hydrogel transitions, hydrogen bonding, metal-ligand coordination, and catechol chemistry [[12], [13], [14], [15]]. Among them, catechol chemistry, inspired by the extraordinary adhesion capabilities of marine mussels, has received particular attention for its ability to form strong bonds with substrates [16]. The strong bond to the substrate generates because of the formation of the interfacial covalent bonds by highly reactive quinones, which is resulted from the oxidation of catechol [17,18]. However, although efforts of incorporating catechol to coacervate had been made in previous study, a systematic investigation into the specific contribution of catechol groups to the coacervates adhesiveness will be very important for further development of practical product in different applications [19,20].

Herein, in this article, a detailed and systematic investigation into the impact of varying catechol grafting ratios, ionic strength influences, and their interaction with different surfaces on adhesive strength has been implemented. We here choose Chitosan as cheaply positive biopolymer, to introduce the catechol group with different graft ratio. The chemical modification of naturally occurring polymer to obtain the catechol-bearing materials, could reduce dependence on synthetic products and consequently positively impact the environment [21,22]. The obtained catechol-grafted Chitosan (Chitosan-C) is then used to form coacervation complex with GA. Our research provides a comprehensive analysis of how these variables affect the formation and adhesion properties of coacervate systems [23,24]. The designed material is further evaluated in different surface to prove universal adhesiveness of these formulations. Additionally, we extend this catechol-modification strategy to various coacervate pairs, including chitosan combine with poly-γ-glutamic acid (PGlu), soybean protein isolate (SPI), and hyaluronic acid (HA), thereby demonstrating the broad applicability and potential of catechol in enhancing coacervate-based adhesives.