Homogeneous Polymerization of Methyl Methacrylate Initiated by Potassium Salts of Methanol and t-Butyl Alcohol in the Presence of Cryptand [222]

Abstract

ABSTRACT:Homogeneous polymerization of methyl methacrylate initiated by potassium salts of methanol and t-butyl alcohol was studied in toluene in the presence of cryptand [222). The polymers prepared were predominantly syndiotactic. The isotacticities increased slightly with an increase in temperature. More than thirty years ago, it was claimed that alkali metal salts of primary alcohols could not initiate the polymerization of methyl methacrylate (MMA) in ether.' More recently, the oligomerization of MMA by CH 3 0-jCH 3 0H solutions has been studied.Z· 3 Oligomers having a degree of polymerization up to six were isolated and characterized. Initiation proceeded by the addition of CH 3 0-to the double bond, and termination by protonation from the methanol.t-Alkoxides, n-butoxides, derivatives of poly(ethylene oxide) of alkali metals as well as ethylmagnesium alkoxides for the initiation of the homogeneous polymerization of methacrylic acid esters have been described in previous papers. 4 -10 It has also been shown that the polymerization of MMA by alkali metal salts of 2-methoxyethanol and like compounds can be carried out in aprotic dipolar solvents such as hexamethylphosphoramide, dimethyl sulfoxide, and dimethylacetamide." Polymerization was greatly promoted by these solvents, even when in small quantities. It is also well known that cryptands such as (I) complex cationic species very strongly and hence promote nucleophilic reactionsY Several studies on the polymerization using such complexing agents have been reported. 13 _,In this paper, we report on the homogeneous polymerization of MMA in toluene by potassium salts of methanol and t-butyl alcohol in the presence of cryptand (1). It was accepted, according to our previous communication, 17 that such complexing agents increase the reactivity of the alkoxide. (Potassium methoxide and t-butoxide are noted respectively MeOK and t-BuOK.) EXPERIMENTAL MaterialsThe purification of toluene and MMA as well as the experimental techniques are described elsewhere.17 Potassium salts of the alcohols were prepared by the reaction of potassium metal with an excess of alcohol in toluene followed by removing solvent and alcohol under vacuum at 100°C during at least 15 hours. This gave the alkoxides as snow-137

Anionic Polymerization of (Meth)acrylates in the Presence of Tetraalkylammonium Halide−Trialkyl Aluminum Complexes in Toluene, 1. Kinetic Investigations with Methyl Methacrylate

“…The value of the persistence ratio, ρ, is close to unity, indicating that the monomer addition follows Bernoullian statistics. These results are similar to those found with a cryptated potassium counterion in toluene …”

Asymmetric End-Capped Poly(ethylene oxide). Synthesis and Rheological Behavior in Aqueous Solution

“…It has been shown that complexing agents of alkali metals increase the reactivity of active centers in anionic polymerization ,, and allow the initiation of heterocyclic monomers . In order to increase the propagation rate, polymerizations were performed in presence of 18-crown-6.…”

Effect of LiClO4 and LiCl Additives on the Kinetics of Anionic Polymerization of Methyl Methacrylate in Toluene‐Tetrahydrofuran Mixed Solvent

“…Additives that have been used in alkyl (meth)acrylate polymerization are alkali metal salts of alkoxide, [22] halides, [6] perchlorates, [23] alkyl silanolates, [24] aluminium alkyls, [25][26][27] and chelating additives such as crown ethers, [28] cryptands, [29,30] pyridine, [31] N,N,N 0 ,N 0 -tetramethylethylenediamine (TMEDA), [32,33] aminoalkoxides, [34] monoalkoxyalkoxides [35,36] and polydentate dilithiumalkoxides. [37] All of these additives coordinate with propagating enolate ion-pairs with different efficiencies and render certain degree of control to the polymerization.…”