Organic catalysis in ring-opening polymerization (ROP) has become a powerful alternative to more traditional metal-based catalysts. The field has developed to a point at which there are not only ...excellent low cost and easy to use organocatalysts for day-to-day polymerizations, but the ability to precisely control the synthesis of advanced polymer architectures and ROP monomers that are extremely challenging to polymerize with other catalysts now exists. This viewpoint article will highlight the key advances in organocatalyst design with the aim of encouraging the wider application of organic catalysts in ROP.
Plastics recycling with a difference Sardon, Haritz; Dove, Andrew P
Science (American Association for the Advancement of Science),
2018-Apr-27, 2018-04-27, 20180427, Letnik:
360, Številka:
6387
Journal Article
Recenzirano
A novel plastic with useful properties can easily be recycled again and again
Since the synthesis of the first synthetic polymer in 1907, the low cost, durability, safeness, and processability of ...polymers have led to ever-expanding uses throughout the global economy. Polymers, commonly called plastics, have become so widely used that global production is expected to exceed 500 million metric tons by 2050. This rising production, combined with rapid disposal and poor mechanisms for recycling, has led to the prediction that, by 2050, there will be more plastic in the sea than fish (
1
). On page 398 of this issue, Zhu
et al.
(
2
) report an important step toward addressing this problem with the synthesis of a plastic with mechanical properties comparable to those of commercially available plastics, but with an intrinsically infinite recyclability.
The current global materials economy has long been inefficient due to unproductive reuse and recycling efforts. Within the wider materials portfolio, plastics have been revolutionary to many ...industries but they have been treated as disposable commodities leading to their increasing accumulation in the environment as waste. The field of chemistry has had significant bearing in ushering in the current plastics industry and will undoubtedly have a hand in transforming it to become more sustainable. Existing approaches include the development of synthetic biodegradable plastics and turning to renewable raw materials in order to produce plastics similar to our current petrol-based materials or to create new polymers. Additionally, chemists are confronting the environmental crisis by developing alternative recycling methods to deal with the legacy of plastic waste. Important emergent technologies, such as catalytic chemical recycling or upcycling, have the potential to alleviate numerous issues related to our current and future refuse and, in doing so, help pivot our materials economy from linearity to circularity.
The vast majority of commodity plastics do not degrade and therefore they permanently pollute the environment. At present, less than 20% of post-consumer plastic waste in developed countries is ...recycled, predominately for energy recovery or repurposing as lower-value materials by mechanical recycling. Chemical recycling offers an opportunity to revert plastics back to monomers for repolymerization to virgin materials without altering the properties of the material or the economic value of the polymer. For plastic waste that is either cost prohibitive or infeasible to mechanically or chemically recycle, the nascent field of chemical upcycling promises to use chemical or engineering approaches to place plastic waste at the beginning of a new value chain. Here state-of-the-art methods are highlighted for upcycling plastic waste into value-added performance materials, fine chemicals and specialty polymers. By identifying common conceptual approaches, we critically discuss how the advantages and challenges of each approach contribute to the goal of realizing a sustainable plastics economy.
The utilization of carbon dioxide as a comonomer to produce polycarbonates has attracted a great deal of attention from both industrial and academic communities because it promises to replace ...petroleum‐derived plastics and supports a sustainable environment. Significant progress in the copolymerization of cyclic ethers (e.g., epoxide, oxetane) and carbon dioxide has been made in recent decades, owing to the rapid development of catalysts. In this Review, the focus is to summarize and discuss recent advances in the development of homogeneous catalysts, including metal‐ and organo‐based complexes, as well as the preparation of carbon dioxide‐based block copolymer and functional polycarbonates.
Poly put the CO2 on! The present review aims to report the updates and challenges in CO2‐based (poly)carbonate synthesis. It focuses on progress realized in the preparation of cyclic carbonate synthons and aliphatic polycarbonate preparation from CO2/epoxide copolymerization. Furthermore, all metal‐based processes are comprehensively discussed and the rapidly developing field of organocatalytic approaches is included.
Aliphatic polycarbonates have gained increased attention as biomaterials largely owing to their biocompatibility and tunable degradation. Moreover, the ability to introduce functional handles in the ...polymer backbone through careful design of cyclic carbonate monomers or copolymerization with other biodegradable polymers has significantly contributed to the interest in exploiting this class of materials for biomedical applications. Such investigations have enabled their utility to be expanded to a wide variety of applications in the biomedical field, from drug delivery to tissue regeneration and the design of vascular grafts. Herein, we review the synthesis, degradation, and studies into biomedical applications of aliphatic polycarbonates obtained by ring-opening polymerization of cyclic carbonate monomers (ring sizes between 6 and 8). While all synthetic methods will be covered, particular emphasis will be given to materials that have been exploited for therapeutic applications in vitro and in vivo.
Polyester-based polymers represent excellent candidates in synthetic biodegradable and bioabsorbable materials for medical applications owing to their tailorable properties. The use of synthetic ...polyesters as biomaterials offers a unique control of morphology, mechanical properties and degradation profile through monomer selection, polymer composition (i.e. copolymer vs. homopolymer, stereocomplexation etc.) and molecular weight. Within this review, the synthetic routes, degradation modes and application of aliphatic polyester- and polycarbonate-based biomaterials are discussed.
Photopolymerization, or the use of light to trigger polymerization, is one of the most exciting technologies for advanced manufacturing of polymers. One of the key components in the ...photopolymerization processes is the photoactive compound that absorbs the light, generating the active species that promotes the polymerization and largely determines the final properties of the material. The field of photopolymerization has been dominated by photoradical generators to mediate radical reactions. In the last decade, to expand the number of polymers that can be prepared by photopolymerization, intensive research has been devoted to the synthesis and utilization of photoactive molecules that are able to generate a base or an acid upon irradiation. These organic compounds are known to promote not only the ring‐opening polymerization of various heterocyclic monomers such as lactones, carbonates, or epoxides but also to trigger the step‐growth synthesis of polyurethanes. This Minireview highlights the recent advances in the development of organic photobase and photoacid generators, with the aim of encouraging the wider application of these photoactive compounds in the photopolymerization area and to expand the use of these polymers in advanced manufacturing processes.
Photopolymerization is a promising method to generate advanced polymers. Particularly significant are photoactive species that form acids or bases upon irradiation by light to initiate polymerization of the monomers. This Minireview highlights the recent advances in the development of organic photobase and photoacid generators.
The ability to control nanostructure shape and dimensions presents opportunities to design materials in which their macroscopic properties are dependent upon the nature of the nanoparticle. Although ...particle morphology has been recognized as a crucial parameter, the exploitation of the potential shape-dependent properties has, to date, been limited. Herein, we demonstrate that nanoparticle shape is a critical consideration in the determination of nanocomposite hydrogel properties. Using translationally relevant calcium-alginate hydrogels, we show that the use of poly(L-lactide)-based nanoparticles with platelet morphology as an adhesive results in a significant enhancement of adhesion over nanoparticle glues comprised of spherical or cylindrical micelles. Furthermore, gel nanocomposites containing platelets showed an enhanced resistance to breaking under strain compared to their spherical and cylindrical counterparts. This study opens the doors to a change in direction in the field of gel nanocomposites, where nanoparticle shape plays an important role in tuning mechanical properties.
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