Purification and Modification of a Biodegradable, Carbone Dioxide Based Polymer: A Sustainable Solution to Reduce Consumption of Non-degradable Plastics

The aim of this study was to develop a benign process for removal of metal residue and other impurities from biodegradable poly(propylene carbonate) (PPC) to broaden its applications. It was demonstrated that the properties of PPC are favourable for fabrication of medical devices and food packaging products. For Instance, mechanical properties of PPC were either comparable or superior to commercial polymers such as low density polyethylene and polybutyrate adipate terephthalate (Eco-Flex). Besides, permeability of PPC to oxygen and moisture was remarkably lower than these polymers. Furthermore, PPC was chemically stable in food simulated media. The high level of zinc glutarate, a metal-based catalyst, in PPC was remarkably reduced by using a novel technique in which CO2 laden water was used as a solvent. The extraction efficiency of this method at 45 ˚C and 70 bar was nearly 90% that was two-fold higher than using acidic solvents. Additionally, at these conditions other impurities such as cyclic propylene carbonate were removed from PPC that further promoted its properties. For example, the thermal decomposition temperature of PPC was shifted from 124˚C to 214˚C and its mechanical strength was enhanced by 40%. Plasma modification was used as an efficient method for chemical immobilization of thymol, an active, natural antimicrobial agent on PPC surface. The results of bacterial counting and bacteria inhibition zone showed that the thymol immobilization was efficient when using plasma at low energy for a period of 15 minutes. This study led to design of two benign processes for purification of PPC and fabrication of its antimicrobial films. This antimicrobial, biodegradable polymer that eradicates the use of preservatives and metal nano-particles is attractive for biomedical devices and food packaging products. Commercialization of theses methods will be of great value for reducing the disposal of non-degradable polymer in landfills that is a huge environmental issue

New Catalytic Systems for Fixation of Carbon Dioxide into Valuable Poly(Alkylene Carbonates)

Fixation of carbon dioxide into valuable products is a promising method to mitigate the issues of global warming and decrease the consumption of fossil-fuel carbon sources. Poly alkylene carbonates (PACs) are environmentally friendly and low-cost polymers that are synthesized from copolymerization of carbon dioxide and epoxides. PACs are contemplated as an alternative to commercially available non-degradable polymers in the market for a broad range of applications. However, a burden for the synthesis of this group of polymers is the chemical activation of thermodynamically stable CO2. It is, therefore, imperative to develop a catalyst with high efficiency to overcome this hurdle. In this chapter, we describe the development and recent advances in the catalytic systems that have been designed to activate CO2 for copolymerization with epoxides. In particular, we will focus on the industrial trends presented in the patents for conversion of CO2 into PACs

A benign process for the recovery of solanesol from tomato leaf waste

Solanesol, the precursor for the synthesis of coenzyme Q10, is currently recovered from tobacco leaves by conventional extraction techniques that require multiple purification steps and a large amount of organic solvents. We recently identified tomato leaves as an alternative source of solanesol and hypothesized that a high-pressure CO2 extraction could be used as a clean extraction process. The effect of CO2 pressure and temperature on the extraction of solanesol was determined to achieve high yield and purity. It was found that solanesol could be extracted efficiently by subcritical CO2 at 25 °C from tomato leaves. The extract contained 40% solanesol and other active compounds such as vitamin K1. A higher level of purity of 93% was achieved using a secondary purification step. Different conventional methods for solanesol extraction was compared to determine the most efficient technique for production of solanesol from tomato leaf. The highest yield of solanesol was achieved at nearly 1% dry weight with using subcritical CO2, which was superior to conventional methods