Final Report: Soy-Capped Polycarbonate Dendrimers for Tough, Sustainable Water Based Wood CoatingsEPA Contract Number: EPD13020
Title: Soy-Capped Polycarbonate Dendrimers for Tough, Sustainable Water Based Wood Coatings
Investigators: Cameron, Randy E.
Small Business: Instrumental Polymer Technologies, LLC
EPA Contact: Manager, SBIR Program
Project Period: May 13, 2013 through November 14, 2013
Project Amount: $80,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2013) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Innovation in Manufacturing
- What is the best method for making the core large enough to offer unique toughness in the cured dendryd? IP TECH found that methanol is necessary during the initial polymerization to make the PE miscible with the DMC. The methanol is easily removed at the end, and the methanol distillate from a previous reaction can be used for the subsequent reaction. With respect to building the highest molecular weight with the most spherical shape, the company found that a stepwise process in which the DMC is added in three aliquots is the best procedure.
- Can the dendryds be formed with a spherical nature to give them low viscosity and excellent flow and wetting so they can permeate into wood? Yes. The viscosity drops during the incubation period with very little drop in average molecular weight, suggesting that the polymers are becoming less entangled and more spherical in nature. The important point is that the viscosity is low enough that the material gets excellent adhesion to wood while being only 90% solids.
- Can carboxylate functionality in the core offer water dispersibility for the dendryds? Yes, though IP TECH needed to change the method for derivatizing the dendrimers with glycine; the resulting material is completely dispersible in water even though the viscosity is low enough for direct applicability.
- Will the fatty groups on the exterior of the dendrimer offer excellent wetting and flow so that flow and wetting agents are not needed? Yes. The dendrimers act very much like a surfactant and wet out very well over metal, wood and plastic substrates.
- Will the carboxylates being in the core, but the crosslinking fatty groups on the surface, offer stain and water resistance? Yes. The wet adhesion and the water drop staining resistance were excellent.
- Will the very high functionality of soy groups on the surface ensure fast and thorough cure so toxic drying agents are not necessary? The cure was fast enough to be marketable; however, it was dramatically improved using a small amount of a more linear version of the same polymer blended with the dendryds.
- Will the high functionality of soy groups and ease of manufacturing keep the cost of the dendryd competitive with alkyds? Yes. As shown below, even with costing from a 500-gallon reactor, which is small in the business, the cost is only $1.43. Considering most alkyds, which are only 60 percent solids in solvent, are $1.75-2.50/lb, this technology is very competitive with current alkyd technology.
During this project, IP TECH was able to demonstrate the production of polycarbonate dendrimers that are covered with soyate groups and that contain the amino acid glycine for water dispersibility. The resulting dendrimers had very low viscosity and could be applied as a coating without use of solvent. The material could be dispersed into water but also could be cured into a film. The company found that the synthesis of the dendrimer, using its evolution polymerization process, needed to begin by prereacting two ingredients, and it was best to add one of the reactants in aliquots. IP TECH optimized the amount of glycine in the core of the dendrimer so it could balance the viscosity of the material, dispersibility of the dendrimer and toughness of the resulting coating. The company also found that a combination of the spherical dendrimers, with a more linear version of the same polymer, yielded better cure and performance properties.