Anhydrous alkali metal hydroxide (KOH, NaOH, and LiOH)-activated macrocyclic ligand complexing metal cations, i.e., coronands 12C4, 15C5, 18C6, DCH24C8, and cryptand C222, were selected for initiation of β-butyrolactone (β-BL) and ε-caprolactone (ε-CL) polymerization. It was found that β-BL polymerizes in the presence of KOH/18C6, KOH/C222, and NaOH/C222 systems. The real initiators in this case are two salts, potassium 3-hydroxybutyrate and potassium trans-crotonate, which are responsible for the formation of two fractions of the obtained polymer. ε-CL underwent polymerization with KOH or NaOH activated by all ligands used or without the ligand but with LiOH/12C4. Using KOH-activated strong ligands, i.e., 15C5, 18C6, or C222, two polymer fractions were generated containing linear and, unexpectedly, also cyclic macromolecules. The mechanism of the studied processes is discussed.. Deprotonation of the monomer and formation of lactone enolate, which decomposes with alkyl-oxygen bond cleavage (with potassium hydride [5] or potassium

Anionic polymerization of propylene oxide was carried out in the presence of two groups of potassium salts activated 18-crown-6 (18C6), e.g. alkoxide salts (CH 3 OK, i-PrOK, t-BuOK, CH 3 OCH 2 CH(CH 3 )OK, KCH 2 O) and other salts (CbK, Ph 3 CK, Ph 2 PK, Ph 3 HBK, KK, KH, and [(CH 3 ) 3 Si] 2 NK) in THF at room temperature. Application of various initiating systems results in polyethers which are different in level and kind of unsaturation represented by allyloxy, cis-and trans-propenyloxy, as well as vinyloxy starting groups. In the presence of selected initiator, i.e. t-BuO -K ? unsaturation increases markedly by addition of 18C6 or C222. During the initiation step oxirane ring-opening and direct deprotonation of the monomer occur simultaneously involving in some cases also the ligand. All initiators opens oxirane ring in the b-position except i-PrOK, which opens it in the b-and a-position. The mechanisms of the reactions were discussed.

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 b-position and not in the b or a 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 b or a 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 (M n = 1700-4800 Da) are much higher than reported in literature for other anionic systems. Dispersity of polymers is rather low (M w /M n = 1.07-1.15) indicating relatively high rate of initiation and cation exchange reaction.

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.

Potassium t-butoxide dissolved in tetrahydrofuran effectively initiates homogeneous polymerization of propylene oxide at room temperature. Unsaturation and molar mass (M n) of the polymers prepared depend on the presence of additives, such as macrocyclic ligand 18-crown-6 (L) and t-butanol. Application of the ligand alone results in distinct increase of unsaturation and decrease of M n, whereas use of t-BuOH leads to simultaneous decrease of unsaturation and M n. Activation of t-BuOK/t-BuOH system with the ligand causes further decrease of unsaturation, that is, from 12.0 to 3.5 mol % for OK/OH (1/3) and OK/OH/L (1/3/2) systems, respectively. Unexpectedly, M n of the polymers obtained does not practically change (~4800). This result differs from that reported earlier for neat PO polymerization initiated potassium 1-methoxy-2-propoxide/1-methoxy-2-propanol, in which in the presence of the same ligand M n increases to ~12 400 for the same ratio of reagents. The mechanism of studied processes was discussed.