High-Glass-Transition Polyesters Produced with Phthalic Anhydride and Epoxides by Ring-Opening Copolymerization (ROCOP)

Abstract

Polyesters with a high glass transition temperature above 130 °C were obtained from limonene oxide (LO) or vinylcyclohexene oxide (VCHO) and phthalic anhydride (PA) in the presence of commercial salen-type complexes with different metals—Cr, Al, and Mn—as catalysts in combination with 4-(dimethylamino) pyridine (DMAP), bis-(triphenylphosphorydine) ammonium chloride (PPNCl), and bis-(triphenylphosphoranylidene)ammonium azide (PPNN3) as cocatalysts via alternating ring-opening copolymerization (ROCOP). The effects of the time of precontact between the catalyst and cocatalyst and the polymerization time on the productivity, molar mass (Mw), and glass transition temperature (Tg) were evaluated. The polyesters were characterized by a molar mass (Mw) of up to 14.0 kg/mol, a narrow dispersity (Tg) of up to 136 °C, and low (<3 mol%) polyether units. For poly(LO-alt-PA) copolymers, biodegradation tests were performed according to ISO 14851 using the respirometric biochemical oxygen demand method. Moreover, the vinyl double bond present in the poly(LO-alt-PA) copolymer chain was functionalized using three different thiols, methyl-3-mercaptopropionate, isooctyl-3-mercaptopropionate, and butyl-3-mercaptopropionate, via a click chemistry reaction. The thermal properties of poly(LO-alt-PA), poly(VCHO-alt-PA) and thiol-modified poly(LO-alt-PA) copolymers were extensively studied by DSC and TGA. Some preliminary compression molding tests were also conducted.

Ring opening polymerization and copolymerization for polyester and polycarbonate formation by a diamino-bis(phenolate) chromium(iii) catalyst

“…The results seen here using 2 can be compared to those of Boggioni and co-workers who used salen chromium complexes and varying co-catalysts to form polyesters from CHO and PA. 25,28 In that work, the chromium catalyst with a PPNCl co-catalyst in a 1 : 1 molar ratio achieved 78% conversion of PA to polyester with a low M n of 1.8 kg mol −1 and high Đ of 3.0 after 0.3 h, while also having a high degree of ether linkages. 25 By employing a “pre-contact step” where the chromium complex and PPNCl, which is poorly soluble in CHO, were combined in toluene to give a soluble species (as was used by us using CH 2 Cl 2 instead of toluene to prepare complex 2 ) more controlled polymerizations were attained ( M n = 9.4 kg mol −1 , Đ = 1.10 after 1 h).…”

“…25 By employing a “pre-contact step” where the chromium complex and PPNCl, which is poorly soluble in CHO, were combined in toluene to give a soluble species (as was used by us using CH 2 Cl 2 instead of toluene to prepare complex 2 ) more controlled polymerizations were attained ( M n = 9.4 kg mol −1 , Đ = 1.10 after 1 h). 25 Further work was done using these catalyst systems on the copolymerization of LO or vinylcyclohexene oxide with PA. 28 Here, the chromium catalyst with PPNCl co-catalyst in a 1 : 1 mixture following pre-contact under similar reaction conditions produced polyesters of LO and PA giving similar M n and Đ observed to those in this work ( M n = 5.7 kg mol −1 , Đ = 1.2 after 3 h compared to Table 2, entry 6 M n = 4.6 kg mol −1 and Đ = 1.25 after 3 h). 28…”

“…25 Further work was done using these catalyst systems on the copolymerization of LO or vinylcyclohexene oxide with PA. 28 Here, the chromium catalyst with PPNCl co-catalyst in a 1 : 1 mixture following pre-contact under similar reaction conditions produced polyesters of LO and PA giving similar M n and Đ observed to those in this work ( M n = 5.7 kg mol −1 , Đ = 1.2 after 3 h compared to Table 2, entry 6 M n = 4.6 kg mol −1 and Đ = 1.25 after 3 h). 28…”

“…26 Boggioni used (salen)MCl catalysts, where M = Cr, Al, and Mn, and determined that formation of high molar mass and T g polymers required a pre-contact step between the catalyst and external nucleophilic co-catalyst. 25,28 Others have shown the importance of a pre-contact step between Cr catalysts and various co-catalysts. 20,29–31…”