Redispersible Polymer Powders with High Bio-Based Content from Core-Shell Nanoparticles

Redispersible polymer powders (RDPPs), i.e., additives obtained from core-shell nanoparticles and commercialized in the form of a dry powder, find intensive application in the concrete industry. However, they are mainly produced from fossil resources. Therefore, the development of bio-based RDPPs is important to reduce the carbon footprint of these additives. In this work, two types of core-shell nanoparticles with a high percentage of bio-based content are synthesized and show to be good candidates as RDPPs. In the first case, up to 75% of bio-based content is obtained by combining lauryl acrylate, derived from coconut and palm kernel oil, as main core material, with isobornyl methacrylate, coming from pine resin, exploited to create the outer harder shell. In the second case, a degradable macromonomer obtained by the ring opening polymerization of lactide using 2-hydroxyethyl methacrylate as initiator is used as the core-forming monomer to obtain degradable RDPPs. In both cases, the particles are synthesized with a two-step emulsion polymerization process conducted in one pot and then spray-dried to obtain the RDPPs of interest. The morphology and redispersibility of the powders are characterized. Finally, their use as concrete additives is preliminarily assessed by evaluating their effect on changes in the surface morphologies of concrete specimens.

Automated summary

Redispersible polymer powders (RDPPs), which are dry powder additives used in the concrete industry, are mainly produced from fossil resources. This study focuses on developing bio-based RDPPs to reduce carbon footprint. Two types of bio-based core-shell nanoparticles were synthesized and found to be promising candidates as RDPPs. The powders were characterized and their potential as concrete additives were evaluated by examining changes in surface morphologies of concrete specimens.