The future direction of sustainable polymers: Eugene Chen / Hong Miao
At present, we can say we live in a material world made of synthetic polymers, synthetic materials have become an integral part of modern life and an integral part of the global economy. Their annual production is increasing year by year, 2050 will reach 1.12 billion tons. However, the production and disposal of synthetic polymers follows a linear unsustainable economic model, including the \”fossil raw materials, acquire, manufacture, use, disposal,\” unidirectional linear frame (FIG. 1). This linear model of economic obsolescence polymer waste can not be solved after consumption, not only the rapid depletion of limited natural resources, but also suffered huge economic losses, aggravated the consequences of plastic pollution and deterioration on a global scale. For various reasons, to recover the polymer, in particular plastic (the highest yield in all types of polymer) is recovered largely ineffective in practice, only 5% of material is recovered for subsequent use. The dire consequences of a double whammy: the
- single-use, every year about 95% of plastic material (worth $ 100 billion) in economic losses, the
- every year there nearly 50 million tons of plastic waste is discarded into landfills and oceans. If you do not do any changes, by 2050, the weight of the plastic in the ocean more than the weight of fish. The human consequences can afford it? The answer is obvious, humans will not be able to bear.
How can we effectively solve the plastic pollution has long been a national, major field of research scientists. Polymer materials research aspects of Hong Miao researcher at the State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry and Professor Eugene Chen Colorado State University has been committed to environmental sustainability, after years of research, found that plastic pollution solve the most effective way to break the plastic pollution unsustainable linear economic model, sustainable development of polymer having a closed-loop lifecycle. They removed the type of \”sustainable polymer\” redefined as \”material derived from renewable raw materials, raw materials, not only in the production and use are safe and pollution-free, and its products can be produced in an environmentally friendly recycled or disposed \”manner as shown in FIG. In This report, they focus on the latest research progress of sustainable polymers, stressed the sustainable development of polyOpportunities and challenges in the process of composition. The papers under the title \”Future Directions for Sustainable Polymers\” published in \”Trends in chemistry\” (see the text description link).
In a conventional polymer sustainable development, plant biomass and biodegradable plastics based. Plant biomass provides abundant renewable resources into a monomer structural unit, and having a negative carbon footprint characteristics nature. At present, the plant biomass-based polymers are polylactic acid and other polyesters or polylactones renewable, biologically derived poly (ethylene terephthalate), poly glycosyl (furan-carboxylic acid ethyl ester), and regeneration polycarbonate. Because a large number of synthetic techniques available to chemists, virtually any monomers may be prepared from renewable raw materials. However, in these transformation process is also accompanied by the question: how many natural resources after step conversion after be used to create a sustainable monomers or polymers? Although a complete life cycle assessment of such processes, while useful, but often impractical. But at least should follow the following guidelines:
- (i) a minimum of converting step;
- (II), and that the conversion efficiency of each step of the maximized atoms;
- ( iii) as a catalytic reaction and the \”green\” condition.
Since the biodegradable polymer which is biodegradable and environmentally friendly species eventually drop thermodynamic heavy, which makes it environmentally friendly potential to establish a closed loop ecosystem. Currently it has achieved application, especially in the short products, such as polyethylene and biomedical packaging lactide, trimethylene carbonate and polyethylene polyhydroxy alkanoate. However, in spite of biodegradable polymers under controlled laboratory conditions microorganisms in the environment can degrade or effective, but they are usually large-scale or degradation in the natural environment (such as a landfill or ocean) is not ideal, this one class of materials will also cause some unforeseen environmental problems. However, the biodegradable polymer by an external stimulus to selectively trigger for waste management orValuable, especially to overcome these challenges after. Although biomass or biodegradable polymer having a recyclable and reduce environmental pollution has certain advantages, but in order to satisfy sustainability system having a closed loop life cycle, the regeneration rate is greater than or equal to resources, resource utilization needs. In this regard, the emerging chemical recycling of polymers can be saved due to the limited natural resources, provide a viable solution for end of life issues polymer waste and recycled materials have the potential to build the economy and are more and more s concern. The recovered polymer may be chemically high selectivity, high yield and high purity monomer is completely depolymerized by chemical means, and may be pure monomer is polymerized directly re-quality polymer. In principle, the process can be repeated indefinitely. Such chemically recycled polymers have significant potential for practical applications, can achieve closed-loop materials economy and prevent the waste of resources from the source. However, to take full advantage of this type of polymer must be chemically recovered address three important challenges ahead: 1 energy costs; 2 dimer selectivity solution; 3 biodegradable balance / performance…. The ideal biodegradable polymer must not only have good thermal and mechanical stability so as to be applied in real life, but also in production must be cost-effective and degrading conditions, a controllable high chemical selectivity the recovery efficiency of the pure monomer. Another class of polymers regeneration areas as innovation, sustainable economic method for preparing a polymer, or to create new materials through the use of higher-value commodity polymers can be used as a large number of cheap raw materials, after giving the new polymer consumption life, thus extending their life. In plan reproduction polymer, a polymer obtained by chemical conversion value is usually easy. Its future challenges, mainly from how to make these processes more cost-effective, and at the same time giving new chemical materials recyclability, so that they are at the end of the service life of the new material does not become the new waste. In this area recyclable polymer recovered using conventional thermosetting resin is one of the most difficult problems, because the crosslinking of the polymer formed neither by mechanical reprocessing, can not be recycled by chemical means. After years of research, research and development is now a class of thermoset material having a dynamic network of covalent (crosslinked) can be further processed, the network may be a covalent association exchange reaction, wherebyReflow of the material upon heating. This \”polymer-based glass\” both in a certain transition temperature, as may be the same thermosetting plastic, solidifying in the network topology, but can be thermally processed image as viscoelastic fluid (at higher temperatures) without losing network integrity. These pioneering academic achievement and high value will stimulate further development of sustainable thermosetting plastic, and can over-respond to a variety of challenges, including:
- (i) polymers with enhanced creep, solvent resistance, heat resistance and chemical resistance can be to overcome the poor, uncontrolled environment;
- (II) a polymer having mechanical and chemical recovery of ductility;
- (iii) a cost-effective, dynamic crosslinking can be mounted to the thermoplastic plastic product having a wide temperature range.
unsustainable nature of synthetic polymers in the future, the development of the sustainable development of polymer having a closed loop life cycle has enormous practical potential, both to protect limited natural resources and provide possible solutions to address the current problem. However, there are still many challenges in achieving this process, in particular the balance between energy costs, recovery / recycling and selective decomposition ability and performance. Thus, a number of studies in the future should focus on the design of innovative development of monomers and polymers as well as structural environment friendly process (e.g. catalytic, without solvent) in the synthesis and recovery of waste material comprising mixed polymers and composites, including polymer. Original link: https: //www.sciencedirect.com/science/article/pii/S2589597419300486#!