# Environmentally Friendly Anticorrosive Polymeric Coatings
## 5 New Trends  
The urgency and necessity to reduce or eliminate VOC in anticorrosive coating formulations has gained increased attention in the last 15-20 years, leading to the three main solutions: water borne, high solid, and UV-curable coatings. These technologies are still being investigated to develop new or improved anticorrosive coating products. However, a huge quantity of low VOC or VOC-free coatings are currently commercially available and are still demanded by the market. New developments are generally improvements of previous products; therefore, they can be considered mature coating technologies. On the contrary, several innovative technologies in the field of environmentally friendly polymeric coatings aimed to fight corrosion of parts or items have recently been identified as new trends. These novel technologies have been summarized in five different groups: smart additives, hyperbranched/hybrid polymer technologies, green corrosion inhibitors, bio-based materials, and superhydrophobic coatings, as depicted in Figure 7.  
The use of smart additives to enhance properties of an anticorrosive coating is a new trend under development. In particular, the use of graphene is attractive due to its excellent anticorrosion properties, in fact graphene acts as a \"barrier\" in the coating, hindering the penetration of the corrosive species and creating a channel of electron flow between the sacrificial anode and the substrate in the coating [86]. For these characteristics, graphene has been added to Zn-rich epoxy coatings, achieving superior corrosion protection and reducing the zinc content in the epoxy primer formulation [87]. Moreover, smart additives such as micro-capsules of environmentally friendly molecules (e.g., lawsone) [88] and zeolites [89] were shown to impart self-curing properties to epoxy resins. Most recently, hyperbranched polymers were used to formulate chemical resistant and low solvent durable coatings, thanks to their good properties such as high cross-linking density, good solubility, and high reactivity. [PERSON] at al [90] applied a water borne  
Figure 7: Schematic representation of new trends in the protective coating fields aiming for environmentally friendly solutions. hyperbranched acrylic polymer grafted onto SiO\({}_{2}\)/TiO\({}_{2}\) composites on steel as a novel coating that passed 1000 h of salt spray test. The use of plant extracts as green corrosion inhibitors has also attracted the attention of the scientific community. As an example, polyphenols extracted from different vegetable sources were employed to enhance the anticorrosive properties of coatings, showing promising results [91, 92, 93]. [PERSON] et al. [94] reported the development of an environmentally friendly epoxy primer using _Pinus Radiata_ tannins extracted from the waste generated by the timber and paper industries. The coating showed an anticorrosive performance comparable to industrial solutions. The inhibitory activity of the extract is attributed to its high antioxidant power, which enables the formation of complexes with the metal surface, creating a protective layer that is impermeable to external agents. An environmentally friendly coating based on the natural product shellac was recently investigated [95]. A significant enhancement in the anticorrosive performance of copper substrates was achieved using aliphatic hydrophobic diamine as a crosslinking agent for modifying shellac structure and ethanol as a solvent. Another relevant example of successful application of bio-based raw material in anticorrosive coatings was the work of [PERSON] et al. [96]. The manuscript described the use of a diol named isophote, which is obtained from glucose at a low cost, as reactant with 3-glycidylopropyltrimethoxysilane to obtain a bio-based epoxy. The coating formulated with the addition of silica nanoparticles and a hydrophobic curing agent improves the corrosion protection. This coating has water-repellent properties as well with a contact angle around 142\({}^{\circ}\).