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

Polyether-pentols (PEPOs) were synthesized from glycidyl ethers and butylene oxide with the application of tripotassium salts of 2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol (HMCH) activated 18C6 for ring-opening polymerization (ROP). The construction of the applied initiator system reflects the ability of crown ether to influence the degree of ion-pair separation with an increased activating effect. As a result formation of bi- or trimodal polymers was observed with molar masses in the range of (Mn = 1200-6000). The observed multi-fraction composition is prescribed to the formation of ionic aggregates with different reactivities during polymerization. The mechanism of the studied processes is discussed. The obtained PEPOs served for a crosslinked PUR synthesis, for which the hydrogen bond index for coupling of hard segments was calculated. Additionally, the range of phase separation was calculated that was higher for PUR-containing aromatic rings as the substituent.

Application of Monopotassium Dipropylene Glycoxide for Homopolymerization and Copolymerization of Monosubstituted Oxiranes: Characterization of Synthesized Macrodiols by MALDI-TOF Mass Spectrometry.

Monopotassium dipropylene glycoxide, activated by a 18-crown-6 cation complexing agent (K-DPG/L, where DPG (dipropylene glycol) is a mixture of isomers) was used as an effective initiator of the homopolymerization and copolymerization of several monosubstituted oxiranes, i.e., propylene oxide (PO), 1.2-butylene oxide (BO), and some glycidyl ethers such as allyl, isopropyl, phenyl, and benzyl ones (AGE, IPGE, PGE, and BGE, respectively). The copolymers are novel and can be prospectively used for the fabrication of new thermoplastic or crosslinked polyurethanes. All processes were carried out in homogeneous mild conditions, i.e., tetrahydrofuran solution at room temperature and normal pressure. They resulted in new unimodal macrodiols with Mn = Mcalc in the range of 1500-8300, low dispersity Mw/Mn = 1.08-1.18 and a chemical structure well defined by several techniques, i.e., MALDI-TOF, size exclusion chromatography (SEC), 13C NMR, and FTIR. Monopotassium salts of homopolyether-diols, i.e., PPO-diol, PBO-diol, and PAGE-diol, appeared to be useful macroinitiators for the preparation of new triblock copolyether-diols by polymerization of glycidyl ethers. In BO/BGE random copolymerization initiated with K-DPG/L, macromolecules of copolyether-diol were exclusively formed. Macromolecules of copolyether-diol accompanied by homopolyether PPO-diol were identified in the PO/PGE system. However, AGE and PGE reacted by giving random copolyether-diol as well as homopolymer-diols, i.e., PAGE-diol and PPGE-diol. Macromolecules of prepared copolyether-diols contain various numbers of mers deriving from comonomers; the kind of comonomer determines the composition of the product. Several prepared homopolyether-diols and copolyether-diols could be useful for the synthesis of new thermoplastic polyurethanes.

The Influence of Crown Ether and Alcohol on Unsaturation and Molar Mass of Poly(propylene oxide)s Prepared by Use of Potassium t-Butoxide: Reinvestigation of Chain Transfer Reactions.

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.

Formation of radical anions and not deprotonation starts the reaction of gamma-butyrolactone with potassium anions.

A mechanism is proposed for the reaction of gamma-butyrolactone with the potassium anion as a two-electron-transfer reagent. Potassium hydride and potassium 4-potassiobutyrate are formed in this process as intermediates. These compounds deprotonate gamma-butyrolactone. Potassium lactone enolate, potassium butyrate, and hydrogen are the final reaction products.

Preparation and decomposition of potassium alkalide-lipophilic crown ether complexes in tetrahydrofuran.

Cyclohexano-15-crown-5, cyclohexano-18-crown-6, dicyclohexano-15-crown-5, and dicyclohexano-18-crown-6, but not dicylohexano-16-crown-5, in THF dissolve potassium metal to form dark blue potassium alkalide solutions at ambient temperature. On standing, the potassium alkalide complexes decompose and the solutions turn colorless at differing rates. Identification of the products provides insight into the decomposition mechanism.