Application of Dipotassium Glycoxides–Activated 18-Crown-6 for the Synthesis of Poly(propylene oxide) with Increased Molar Mass

Abstract

Mono-and dipotassium salts of dipropylene glycol were applied for the polymerization of propylene oxide in mild conditions, i.e., tetrahydrofuran solution at ambient temperature. The structure of polymers was investigated by use of 13 C NMR and MALDI-TOF techniques. The structure depends strongly on the kind of initiator and additives that are used such as coronand 18-crown-6 and dipropylene glycol. The lowest unsaturation, represented by allyloxy starting groups, has the polymer obtained by use of monopotassium salt without the ligand. The highest unsaturation degree is for the polymer synthesized in the presence of dipotassium salt-activated 18-crown-6. This polymer, obtained at high initial monomer concentration and low initial concentration of initiator, consists of two fractions, i.e., a low molar mass fraction (M n ¼ 9400) containing mainly macromolecules with alkoxide starting and end groups and a much higher molar mass fraction (M n ¼ 29500 g/mol) containing macromolecules with allyloxy starting groups and alkoxide or hydroxyl end groups. Addition of free glycol to this system decreases the molar mass of polymers. Similar results were obtained by use of dipotassium salts of other glycols. The mechanisms of the studied processes are discussed.

Ring-opening polymerization of monosubstituted oxiranes in the presence of potassium hydride: determination of initiation course and structure of macromolecules by MALDI-TOF mass spectrometry

“…It was known [3,12], that cisand trans-propenyloxy groups resulted from isomerization of allyloxy groups. However, two signals of isopropoxy groups could come from two different chain beginnings formed during initiation [14]. However, MALDI-TOF spectrum of the polymer revealed several series of signals, which belong to three kinds of macromolecules (Fig.…”

“…Initiators most frequently used for polymerization of monosubstituted oxiranes, e.g. PO are potassium hydroxide [10][11][12] and potassium salts of alcohols, glycols or glycerol [13][14][15]. In some cases cation complexing agents, e.g.…”

“…In some cases cation complexing agents, e.g. coronand 18-crown-6 were applied for activation of chain growth centers [14,16,17]. Other salts for example as potassium potasside K + (15-crown5) 2 K − [18,19] or potassium hydride K + H − /activated with various crown ethers [20][21][22][23] were also used for initiation of the polymerization of many oxiranes.…”

New Star-Shaped Polyether-Pentols (PEPOs) for Fabrication of Crosslinked Polyurethanes—Synthesis and Characterization

“…Recently [ 10 ], we used for initiation dipotassium salts of different glycols (e.g., di- or tripropylene ones, activated 18-crown-6 (18C6)). It allowed preparing bimodal PPOs containing fraction with two terminal OK groups ( M n ~10,000) and fraction with allyloxy and OK terminal groups ( M n ~30,000).…”