Poly(THF-co-cyano ethylene oxide): Cyano Ethylene Oxide (CEO) Copolymerization with THF Leading to Multifunctional and Water-Soluble PolyTHF Polyelectrolytes

Using Redox-Switchable Polymerization Catalysis to Synthesize a Chemically Recyclable Thermoplastic Elastomer

In an effort to synthesize chemically recyclable thermoplastic elastomers, a redox-switchable catalytic system was developed to synthesize triblock copolymers containing stiff poly(lactic acid) (PLA) end blocks and a flexible poly(tetrahydrofuran-co-cyclohexene oxide) (poly(THF-co-CHO) copolymer as the mid-block. The orthogonal reactivity induced by changing the oxidation state of the iron-based catalyst enabled the synthesis of the triblock copolymers in a single reaction flask from a mixture of monomers. The triblock copolymers demonstrated improved flexibility compared to poly(l-lactic acid) (PLLA) and thermomechanical properties that resemble thermoplastic elastomers, including a rubbery plateau in the range of -60 to 40 °C. The triblock copolymers containing a higher percentage of THF versus CHO were more flexible, and a blend of triblock copolymers containing PLLA and poly(d-lactic acid) (PDLA) end-blocks resulted in a stereocomplex that further increased polymer flexibility. Besides the low cost of lactide and THF, the sustainability of this new class of triblock copolymers was also supported by their depolymerization, which was achieved by exposing the copolymers sequentially to FeCl3 and ZnCl2 /PEG under reactive distillation conditions.

Influence of Rigid Segment Type on Copoly(ether-ester) Properties

The growing ecological awareness of society created the tendency to replace petrochemically based materials with alternative energy carriers and renewable raw materials. One of the most requested groups of polymer materials with significant technological importance is thermoplastic elastomers (TPE). They combine the properties of elastomers such as flexibility with the typical properties of thermoplastics, like easy processing. Herein, one compares the influence of rigid segments on the properties of copoly(ester-ether). Thermoplastic polyesters based on bio-1,6-hexanediol and terephthalic (T), furanic (F), and napthalate (N) diesters, i.e., PHT, PHF, and PHN, were obtained employing melt polycondensation. Additionally, to grant elastic properties of polyesters, systems containing 50 wt.% of bio-based polyTHF^®1000 (pTHF) with a molecular mass of 1000 g/mol, have been prepared. The composition and chemical structure have been determined by ¹H nuclear magnetic resonance (NMR) and Fourier transformed infrared spectroscopy (FTIR) analyses. The temperatures corresponding to phase transition changes were characterized by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) analyses. The crystalline structure was examined by X-ray diffraction (XRD) analysis. Additionally, the influence of pTHF–rich segment on the tensile properties, water absorption, as well as thermal and thermo-oxidative stability, has been analyzed. It was found that incorporation of soft phase allows creation of thermoplastic elastomers with tensile characteristics comparable to the commercially available ones, by means of elongation at break higher than 500%, low values of tensile modulus, without exhibiting yield point.

Polypropylene Glycol-Polyoxytetramethylene Glycol Multiblock Copolymers with High Molecular Weight: Synthesis, Characterization, and Silanization

The high crystallization at room temperature and high cost of polyoxytetramethylene glycol (PTMG) have become obstacles to its application. To overcome these problems, a segment of PTMG can be incorporated into a block copolymer. In this work, polypropylene (PPO) glycol-polyoxytetramethylene (PPO-PTMG) multiblock copolymers were designed and synthesized through a chain extension between hydroxyl (OH)-terminated PPO and PTMG oligomers. The chain extenders, feed ratios of the catalyst/chain extender/OH groups, reaction temperature, and time were optimized several times to obtain a PPO-PTMG with low crystallization and high molecular weight. Multiblock copolymers with low crystallization and high average molecular weight (M_n = 1.0–1.4 × 10⁴ Dalton) were harvested using m-phthaloyl chloride as the chain extender. The OH-terminated PPO-PTMG multiblock copolymer with high M_n and a functionality near two was further siliconized by 3-isocyanatopropyltrimethoxysilane to synthesize a novel silyl-terminated polyether. This polyether has an appropriate vulcanizing property and potential applications in sealants/adhesive fields.