Synthesis of high molecular weight aromatic polyesters via integrated alternating ring‐opening copolymerization and chain extension methods

Abstract

Due to their good mechanical properties, high molecular weight polyesters (PEs) are highly desirable for a wide range of applications especially in the packaging industry. However, the synthesis of high molecular weight polymers by energy efficient methods is difficult. In this study, a series of semi‐aromatic PEs were synthesized via the alternating ring‐opening copolymerization (ROCOP) of phthalic anhydride (PA) and cyclohexene oxide (CHO) using a salen chromium(III) complex as a catalyst and 4‐(dimethylamino)pyridine as a cocatalyst. By varying the molar ratios between CHO and PA, PEs of different molecular weights were obtained. Hexamethylene diisocyanate was used as a chain extender that further increased the molecular weights of these PEs. These chain extended aromatic polyesters (PE‐Xs) showed significant improvement in the glass transition temperature (Tg) values. Thus, integration of ROCOP with the chain extension method can be used as an effective strategy to prepare high molecular weight PEs with improved thermal stabilities and enhanced mechanical properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47200.

Green analogs of polybutadienes from carbon dioxide and epoxy‐based feedstocks

“…However, the peaks observed in these GPC traces are bimodal (for example, RUPC2 exhibits two peaks). This bimodal peak distribution corresponds to the copolymerization initiated by the moisture to allow the RUPC to grow on both sides, as supported by prior literature 24,23 . Meanwhile, the GPC analysis of RUPC2‐ g ‐PS revealed that the M n of this copolymer had increased to 35,682 Da due to the grafting of PS chains onto the RUPC2 backbone as well as the polystyrene homopolymer formation.…”

“…This bimodal peak distribution corresponds to the copolymerization initiated by the moisture to allow the RUPC to grow on both sides, as supported by prior literature. 24,23 Meanwhile, the GPC analysis of RUPC2-g-PS revealed that the M n of this copolymer had increased to 35,682 Da due to the grafting of PS chains onto the RUPC2 backbone as well as the polystyrene homopolymer formation. Four overlapped peaks are visible in the GPC trace of RUPC2-g-PS corresponding to the uncreated RUPC2, the PS homopolymer, and RUPC2-g-PS.…”

“…Gel permeation hromatography (GPC) was used to determine the number average molecular weight ( M n ), weight average molecular weight ( M w ), viscosity average molecular weight ( M V ), and the polydispersity index (PDI) of each of the prepared polymers. A Waters Corp. (Milford, MA, USA) GPC instrument was used, which was equipped with a Waters 1515 isocratic pump, a Waters 717 autosampler, Waters Styragel columns including HR4, HR3, and HR2 (300 mm × 7.8 mm [I.D]) columns, as well as a Waters 2414 refractive index detector 23,24 . The samples were prepared by dissolving ~2 mg of each polymer sample in 1 ml of THF in a 5 ml vial.…”

“…A Waters Corp. (Milford, MA, USA) GPC instrument was used, which was equipped with a Waters 1515 isocratic pump, a Waters 717 autosampler, Waters Styragel columns including HR4, HR3, and HR2 (300 mm × 7.8 mm [I.D]) columns, as well as a Waters 2414 refractive index detector. 23,24 The samples were prepared by dissolving~2 mg of each polymer sample in 1 ml of THF in a 5 ml vial. The solution was filtered and was transferred to a GPC vial.…”

Synthesis and Studies on Aromatic Copolyester With Anticancer Activity Derived From 4,4’- Dihydroxybiphenyl and 3,5-Dihydroxytoluene

“…Some characteristic absorptions appeared in the spectrum, such as C-H stretching near 2900 cm -1 . 26 The copolyester shows distinctive carbonyl stretching absorption bands of the ester group near 1760 cm -1 , substantiating the presence of ester linkages in the polyester. The band near 1230 cm -1 (ester C-O stretching) also validates the presence of ester moieties in the polymer sample, as reported by Kandaswamy, N. 27 The broad detectable band around 3469 cm -1 , due to hydroxyl group stretching vibration, is also observed.…”