Search

Polyolefin thermoplastic elastomers (TPE‐Os) are high‐performance polyolefins consisting of both plastic and rubber phases. Compared with other thermoplastic elastomers, the TPE‐Os possess better chemical stability, transparency, re‐processability, and electrical insulation, which renders their broad applications possible. By manipulating chain structures and topologies of the TPE‐Os, differently structured polyolefins with improved thermal and mechanical properties have been developed, including ethylene and α‐olefin random copolymers (POEs), olefin block copolymers (OBCs), comb‐shaped polyolefin elastomers (CPOEs), and dynamically cross‐linked polyolefin elastomers. Herein, we review the synthesis of the POE, OBC, CPOE, and dynamical cross‐linked polyolefin elastomer, including the catalyst systems, polymerization techniques, processes, and kinetic modelling. The characterization of the TPE‐Os and the relationships between the TPE‐O chain structure, aggregated state, and product performance are discussed. The future development of higher‐performance TPE‐Os is envisaged. [ABSTRACT FROM AUTHOR]

Cellulose nanofibrils (CNFs) are a class of emerging sustainable nanomaterial. Among all their advantages, their high surface charge offers high colloidal stability, while their higher aspect ratio favors the mechanical properties of the corresponding network materials. In order to obtain such CNFs, harsh chemical pretreatments are usually applied, leading to inferior eco-friendly characteristics for CNFs. Herein, we report an eco-friendly pretreatment using maleic anhydride (MA) esterification at a low reaction temperature of less than 100 °C without the addition of any organic solvent or toxic catalyst. Up to 83% of unreacted MA in the pretreatment can be recovered. The resultant MA-CNFs have a high surface charge density (1.6 mmol g−1) while maintaing a high aspect ratio of 390, which cannot be achieved using conventional chemical pretreatment. Moreover, the interfibrillar interaction can be well tuned through the surface MA groups, which translates to superior mechanical properties for nanopaper films possessing ultrahigh toughness (16.4 MJ m−3) and folding endurance (3.68), as well as a high transmittance of up to 88%. Altogether, this work enhances the performance of cellulosic materials in an eco-friendly manner, and provides a promising candidate for advanced nanofilm applications, which conventional materials based on pulp fibers or petroleum-based polymers will not be able to reach. [ABSTRACT FROM AUTHOR]

Two series of triblock copolymers, polycaprolactone‐b‐polybutadiene‐b‐polycaprolactone (PCL‐b‐PB‐b‐PCL, CBC) and polylactide‐b‐polybutadiene‐b‐polylactide (PLA‐b‐PB‐b‐PLA, LBL), have been synthesized through the ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL)/D,L‐lactide (D,L‐LA) catalyzed by Sn(Oct)2 with hydroxyl‐terminated polybutadiene (HTPB) as a macroinitiator. Then, these triblock copolymers are end‐functionalized with 2‐ureido‐4[1H]‐pyrimidinone (UPy) groups to obtain the supramolecular multiblock copolymers UCBC and ULBL as supramolecular thermoplastic elastomers (TPEs). The thermal properties of UCBC and ULBL samples are measured by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The tensile tests of all the samples prepared are carried out to investigate the influence of the content of hard segments and the microstructure of PB soft segments on the mechanical properties of supramolecular TPEs. [ABSTRACT FROM AUTHOR]