Co-Oligomers of Renewable and “Inert” 2-MeTHF and Propylene Oxide for Use in Bio-Based Adhesives

Abstract

Commercial polyether polyols are usually obtained by the ring-opening polymerization of epoxides or tetrahydrofuran. 2-Methyl-tetrahydrofuran (2-MeTHF) could be an alternative bio-based building block for the synthesis of these polyols. Although 2-MeTHF cannot be polymerized, we did achieve the copolymerization of 2-MeTHF with propylene oxide (PO) using Lewis and Brønsted acids as catalysts and water or diols as initiators. The resulting polyether polyols have a molecular weight range, which allows their use as components for adhesives. The molar content of 2-MeTHF in the oligomers can be up to 48%. A 1:1 copolymer of 2-MeTHF and PO is produced when stoichiometric amounts of BF3·OEt2 are used. Here, the monomeric units in the chains alternate, but also cyclic or other nondiol products are formed that are detrimental to its further use in adhesives. Linear dihydroxyl-terminated polyether chains were formed when the heteropolyacid H3PW12O40·24H2O was used as a catalyst and a diol as an initiator. The formation of cyclic products can be drastically reduced when the accumulation of propylene oxide during the reaction is avoided. 1H NMR experiments indicate that the step of 2-MeTHF incorporation is the alkylation of 2-MeTHF by protonated PO. It was shown that the 2-MeTHF/PO copolymer had increased tensile strength compared to polypropylene glycol in a two-component adhesive formulation.

Zr(IV) Catalyst for the Ring-Opening Copolymerization of Anhydrides (A) with Epoxides (B), Oxetane (B), and Tetrahydrofurans (C) to Make ABB- and/or ABC-Poly(ester-alt-ethers)

“…All of the new polymers are amorphous and show glass-transition temperatures that get progressively lower with increasing THF selectivity ( T g = −3 to −5 °C, Figure S51). Bio-derived 2-methyl tetrahydrofuran (MeTHF), synthesized from sugars, was also investigated in reactions with PA and BO (Table , #6–8) . Using this monomer likewise resulted in successful formation of poly­(ester- alt -ethers) with up to 29% MeTHF incorporation (Figures S36–S39).…”

“…Bio-derived 2-methyl tetrahydrofuran (MeTHF), synthesized from sugars, was also investigated in reactions with PA and BO (Table 2, #6−8). 54 Using this monomer likewise resulted in successful formation of poly(ester-alt-ethers) with up to 29% MeTHF incorporation (Figures S36−S39). Its NMR spectra show, in addition to the expected key assignments (no 1 H− 1 H COSY correlation between the methine-ester and methylene-ester, δ H = 5.13 and 4.35 ppm, respectively), the characteristic −CH 3 resonance from ringopened MeTHF at 1.20 ppm.…”

Catalytic production of tetrahydropyran (THP): a biomass-derived, economically competitive solvent with demonstrated use in plastic dissolution

“…However, in some cases, a low ring strain monomer can be incorporated into polymer chains by copolymerization with a high ring strain comonomer. 44,45 Therefore, the copolymerization of THP (low ring strain) and THF (high ring strain) was further explored. The results are shown in Table 6, which indicated that only THF was selectively polymerized (Fig.…”

Poly(ester-co-ether) from ring-opening copolymerisation of sustainable 2-methyltetrahydrofuran with β-butyrolactone

“…de Vries et al realized the copolymerisation of propylene oxide with 2-MeTHF using phosphotungstic acid as the catalyst, and obtained a polyether with a relatively low molecular weight of 2 kg mol −1 . 20 Williams and co-workers investigated the terpolymerisation of phthalic anhydride with butylene oxide and 2-MeTHF. 21 They found that the copolymers contained a maximum 2-MeTHF content of 26 mol% under the condition where excessive 2-MeTHF in feed was required up to 15 times that of acid anhydride.…”