Abstract
It was stated that initiation in ring opening polymerization of styrene oxide depends on the kind of potassium alkoxide activated by 18-crown-6 used. In the presence of potassium methoxide the oxirane ring opening occurs exclusively in the β-position and not in the β or α position, i.e., contrary to the previous data. A similar result was obtained in the systems initiated with potassium t-butoxide, 2-methylpropoxide and 1-phenylethoxide. Unexpectedly, potassium i-propoxide and 1-methylpropoxide open the oxirane ring in the β or α position. In all polymerizations, deprotonation of methine group in the monomer takes place under the influence of the initiator and in chain transfer reaction to the monomer. It leads to the formation of macromolecules with unsaturated starting group. However, deprotonation of methylene group in the monomer does not occur. Applying of potassium hydroxyalkoxides, i.e., monopotassium salt of dipropylene glycol or tripotassium salt of 2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol it was possible to synthesize PSO-diols and PSO-pentols without unsaturation. Molar masses of polymers (Mn = 1700–4800 Da) are much higher than reported in literature for other anionic systems. Dispersity of polymers is rather low (Mw/Mn = 1.07–1.15) indicating relatively high rate of initiation and cation exchange reaction.
Highlights
The literature data dedicated to anionic ring opening polymerization of styrene oxide (SO) are rather scarce [1,2,3,4,5,6]
It was stated that initiation in ring opening polymerization of styrene oxide depends on the kind of potassium alkoxide activated by 18-crown-6 used
13C nuclear magnetic resonance (NMR) was used as the main technique for analysis of the polymers obtained in order to determine the course of ROP
Summary
The literature data dedicated to anionic ring opening polymerization of styrene oxide (SO) are rather scarce [1,2,3,4,5,6]. The papers present the course of the process mediated with sodium [4] or potassium methoxide [2, 3]. It was reported that these compounds open the oxirane ring in the SO molecule in two positions, i.e., a or b, the latter even prevails (*67%) during initiation of the polymerization. During propagation the oxirane ring opens exclusively in the b-position. Potassium hydride was used for SO polymerization [5]; the course of the process was not proposed.
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