Green Processes for Green Products: The Use of Supercritical CO₂ as Green Solvent for Compatibilized Polymer Blends

• Main Authors: Muhammad Iqbal, Christiaan Mensen, Xiaohua Qian, Francesco Picchioni
• Format: Article
• Language: English
• Published: MDPI AG 2018-11-01
• Series: Polymers
• Subjects: starch; polycaprolactone; glycidyl methacrylate; compatibilization; supercritical carbon dioxide; mechanical properties
• Online Access: https://www.mdpi.com/2073-4360/10/11/1285

Polycaprolactone-<i>g</i>-glycidyl methacrylate (PCL-<i>g</i>-GMA), a reactive interfacial agent for PCL-starch blends, is synthesized using supercritical carbon dioxide (scCO₂) as reaction medium and relatively high molecular weight PCL (<i>M</i>_w = 50,000). Higher GMA and radical initiator intakes lead to higher functionalization degrees (FD) for PCL-<i>g</i>-GMA samples. A mathematical model is developed to describe the correlation between monomer and initiator intake and FD values. The model shows an excellent R²-value (0.978), which implies a good fit of the experimental data. Comparison of this model with a similar one for the reaction in the melt clearly indicates a better reaction efficiency in scCO₂. Furthermore, GPC results show that less degradation occurred for samples made in scCO₂. Finally, the use of the PCL-<i>g</i>-GMA made in scCO₂ (as interfacial agent) in ternary blend of PCL/starch/PCL-<i>g</i>-GMA results in better mechanical properties with respect to those obtained by using the same graft-copolymer as prepared in the melt.