Abstract
Several new polyether-diols were prepared by ring-opening polymerization of monosubstituted oxiranes in the presence of anhydrous potassium hydroxide. 1,2-Butylene oxide (BO), styrene oxide (SO), isopropyl glycidyl ether (IPGE), allyl glycidyl ether (AGE), phenyl glycidyl ether (BGE), p-methoxyphenyl glycidyl ether (MPGE) and benzyl glycidyl ether (BGE) were chosen as monomers. Macrocyclic ligands complexing metal cations, i.e. coronand 18C6 or cryptand C222 were used as activators in these systems. All polymerizations were carried out in tetrahydrofuran solution at room temperature. Molar mass (Mn) and dispersity (Mw/Mn) of the polymers obtained with KOH depends on the kind of monomer, initial concentration of the initiator and the presence and kind of ligand or water. For example, PBO-diols prepared without ligand are bimodal and for the main fraction Mn > Mcalc. However, after addition of 18C6 polymers are unimodal and unexpectedly have much higher Mn = 13,700–15,800 and very low dispersity (Mw/Mn = 1.04–1.08). Mn of PBO-diols decrease with increase of [KOH]o and do not change at [BO]o = 2.0–9.0 mol/dm3. Addition of C222 results in Mn decrease of PBO-diols. Similar effects were observed in the polymerization of PAGE-diols and PPGE-diols. In the polymerization of SO, PGE, MPGE and BGE initiator efficiency (f) is high and Mn < Mcalc. Polymodality of some polymers obtained was discussed in term of the formation of various species propagating with different rate constants.Graphical abstractPolyether-diols synthesized using anhydrous hydroxide as initiator.
Highlights
Polyethers, especially poly(propylene oxide)s belong to important class of polymers due to their thermal and chemical stability as well physical and mechanical properties resulting in wide applications such as impact modifiers, surfactants, deemulsifiers, dispersant agents, fuel additives, wetting agents, lubricants, rheological modifiers, biomedical materials and adhesives [1,2,3,4,5,6,7]
The results presented below concern the most important and interesting phenomena observed in the polymerization of chosen oxiranes initiated with anhydrous KOH
Of dispersion, KOH activated by coronand 18C6, partially hydrated KOH activated by 18C6 and KOH activated by cryptand C222
Summary
Polyethers, especially poly(propylene oxide)s belong to important class of polymers due to their thermal and chemical stability as well physical and mechanical properties resulting in wide applications such as impact modifiers, surfactants, deemulsifiers, dispersant agents, fuel additives, wetting agents, lubricants, rheological modifiers, biomedical materials and adhesives [1,2,3,4,5,6,7]. Propylene oxide have been polymerized by many procedures involving ring-opening polymerization (ROP) in bulk [9,10,11]. The most popular anionic initiators used are alkali metal alkoxides or hydroxides. It was observed, that KOH, RbOH and CsOH are effective initiators, while LiOH and NaOH are ineffective ones, probably due to their very low solubility in liquid monomer [12]. That KOH, RbOH and CsOH are effective initiators, while LiOH and NaOH are ineffective ones, probably due to their very low solubility in liquid monomer [12] It was established by Steiner et al [13], that PO polymerization initiated by solid anhydrous KOH is not surface-catalyzed. During the polymerization in tetrahydrofuran (THF) solution great amount of macromolecules with unsaturated starting groups appears, resulting
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