Novel, semicrystalline polyamides and co(polyamides) were synthesized from biobased sebacic acid (SA), 2,5-diamino-2,5-dideoxy-1,4;3,6-dianhydroiditol (diaminoisoidide, DAII) as well as from 1,4-diaminobutane (DAB), also known as putrescine in nature. Low molecular weight polyamides were obtained by melt polycondensation of the salts based on these monomers or by interfacial polycondensation. In order to increase their molecular weights the polyamide prepolymers were submitted to a solid state polymerization (SSP) process. The chemical structure of the polymers was confirmed by 2D NMR correlation spectra (COSY), heteronuclear multiple-bond correlation spectra (HMBC) and by FT-IR spectroscopy. In the present work, FT-IR and X-ray techniques were used as a tool for the investigation of the crystal structure of the polymers after SSP. The X-ray diffractograms of the polyamides point to crystals containing both 4.10- and DAII.10-based repeat units. Because of the presence of diaminoisoidide residues the synthesized fully renewable products exhibit tunable polarities and melting points. Since most commercial polyamides have a much higher melting point than their end application requires, especially for fiber applications, this simple adaption can result in a significant reduction of energy consumption during processing.

Here we present a novel series of biobased polyesters solely based on renewable isohexide building blocks, synthesized via melt polymerization. The recently developed isoidide dicarboxylic acid (IIDCA) was polymerized with rigid renewable diols such as isosorbide (IS), isomannide (IM), isoidide (II), and the novel 2,5-methylene-extended isoidide dimethanol (IIDML). Both IIDCA and IIDML were developed to increase the reactivity of the isohexide building block, while retaining rigidity and hence the beneficial effects on T g . Compared to the parent isohexides, IIDML showed a markedly higher reactivity, resulting in three to four times higher weight-average molecular weight (M w ) values of the synthesized polyesters. The molecular structure of the novel polyesters was analyzed by 1 H, 13 C and 2D-COSY NMR techniques, confirming that the stereoconfigurations of the isohexide moieties were preserved under the applied polymerization conditions. The II/IS-based polyesters have high T g values noted of 70 and 85 °C, respectively, while the IIDML-based polyester has a lower T g of approximately 45 °C, yet with an higher degree of crystallinity than the parent isohexide-based polyesters. A systematic study on structure-thermal properties relations comparing these novel polyesters with, e.g., aliphatic polyesters reveals that, when incorporated into polyesters, both IIDCA and IIDML are able to increase the T g by approximately 70 °C, which is comparable to the parent isohexides. Given the enhanced reactivity, high thermal stability and the retained ability to increase the T g , IIDML is a promising renewable building block for performance polymers.

Hextended family: A new family of C2/C5 carbon‐extended isohexide derivatives is synthesized in a stereo‐controlled manner with high purity and good yield. These chiral and rigid biobased building blocks can be widely applied: in pharmaceuticals, cholesteric liquid crystals, and as building blocks for high‐performance polymers. The isoidide‐based diacid is a potential renewable alternative to terephthalic acid.

Isohexides, like e.g. isosorbide, are well-known carbohydrate-based rigid diols which are capable of dramatically increasing the glass transition temperature of polyesters. However, their relatively low reactivity has thus far hampered large-scale industrial applications in the polymer field. Recently, with the aim to increase reactivity while at the same time retain rigidity, we have developed a new isoidide dicarboxylic acid (IIDCA) by transforming the secondary hydroxyls into carboxylate functionalities. Here we report the first polymers based on IIDCA and linear α,ω-diols. The novel polyesters were obtained via melt polymerization and exhibited weight-average molecular weights in the range of 13 000−34 000 g/mol and polydispersities close to 2.0. NMR analyses showed that the exo−exo configuration of the isoidide dicarboxylate units was preserved during synthesis. Both differential scanning calorimetry and wide-angle X-ray diffraction analyses showed that the IIDCA polyesters are semicrystalline materials. A systematic study on structure−thermal properties relations among relevant series of polyesters, such as isomeric polymers based on isoidide, revealed several interesting differences in melting and glass transition temperatures, which are thought to be related to variations in chain packing and free volume.

No abstract

No abstract

No abstract

Microplastics are an emergent yet critical issue for the environment because of high degradation resistance and bioaccumulation. Unfortunately, the current technologies to remove, recycle, or degrade microplastics are insufficient for complete elimination. In addition, the fragmentation and degradation of mismanaged plastic wastes in environment have recently been identified as a significant source of microplastics. Thus, the developments of effective microplastics removal methods, as well as, plastics recycling strategies are crucial to build a microplastics‐free environment. Herein, this review comprehensively summarizes the current technologies for eliminating microplastics from the environment and highlights two key aspects to achieve this goal: 1) Catalytic degradation of microplastics into environmentally friendly organics (carbon dioxide and water); 2) catalytic recycling and upcycling plastic wastes into monomers, fuels, and valorized chemicals. The mechanisms, catalysts, feasibility, and challenges of these methods are also discussed. Novel catalytic methods such as, photocatalysis, advanced oxidation process, and biotechnology are promising and eco‐friendly candidates to transform microplastics and plastic wastes into environmentally benign and valuable products. In the future, more effort is encouraged to develop eco‐friendly methods for the catalytic conversion of plastics into valuable products with high efficiency, high product selectivity, and low cost under mild conditions.