Synthesis of a Hetero Telechelic Hyperbranched Polyether. Anionic Ring-Opening Polymerization of 3-Ethyl-3-(hydroxymethyl)oxetane Using Potassium tert-Butoxide as an Initiator

Abstract

KEY WORDSHetero Telechelic Hyperbranched / Anionic Polymerization / Polyethers / 3-Ethyl-3-(hydroxymethyl)oxetane / Oxetanes with 4-membered ring are polymerized exclusively with cationic initiators, due to high basicity. 1 Vandenberg et al. reported that cationic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)-oxetane (EHO) in the presence of aluminum complexes as cationic initiators produced linear polymers with high crystallinity and no glass transition temperature. 2, 3 Hyperbranched polymers by cationic ring-opening polymerization of EHO using sulfonium salts as cationic initiators have been reported. [4][5][6][7] Inoue et al. performed living anionic polymerization of oxetanes using aluminum porphyrin/Lewis acid as catalyst. 8 The authors have developed useful reactions of oxetanes for synthetic organic chemistry and polymer synthesis. 9 No research has been done on the anionic polymerization of oxetanes using common anionic initiators such as butyllithium (BuLi), sodium methoxide (MeONa), potassium tert-butoxide (t-BuOK) and etc.Herein, we describe successful results of the anionic ring-opening polymerization of oxetane, 3-ethyl-(3-hydroxymethyl)oxetane (EHO), affording hetero telechelic hyperbranched polyethers, poly(EHO)s containing an oxetanyl and many hydroxyl groups at the ends. EXPERIMENTAL Materials18-Crown-6-ether (18-C-6) was recrystallized twice from acetnitrile. t-BuOK was purified by the sublimation. 3-Ethyl-3-(hydroxymethyl)-oxetane (EHO) was donated from Toagosei Co., Ltd. and distilled over MgSO 4 before use. InstrumentationInfrared (IR) absorption spectra were measured on a Jasco model IR-420 spectrometer. 1 H and 13 C NMR spectra were recorded on a JEOL model JNM α-500 (500 MHz for 1 H NMR and 125 MHz for 13 C NMR) in DMSO-d 6 with Me 4 Si (TMS) as internal standard. The degree of branching was calculated from relative intensity of the -CH 2 CH 3 in proton decoupled, quantitative 13 C NMR spectra. Number-average molecular weight (M n ) and weight-average molecular weight (M w ) of the polymers were estimated by gel permeation chromatography (GPC; TOSOH model HLC-8020) on TSK gel Multipore Hxl-M columns calibrated by narrow molecular weight polystyrene standards and with solution of LiBr and phosphoric acid (20 mM) in dimethylformamide (DMF) as eluent without correction with a refractive index detector. T g s were measured on a Seiko Electronic Instrument (SSC5200/DSC120) differential scanning calorimeter (DSC) at a heating rate of 10 • C min −1 under a nitrogen atmosphere. Thermal analysis was performed on a Seiko Electronic Instrument (TG/DTA 120) at a heating rate of 10 • C min −1 for thermogravimetric analysis (TGA) under nitrogen. Matrixassisted laser desorption ionization time-of flight mass (MALDI-TOF-MS) experiments were performed SHI-MAZU/KRATOS MALDI-TOF-MS using dihydroxy benzoic acid as matrix and chloroform as solvent. Synthesis of Hyperbranched Polyethers by the Polymerization of 3-Ethyl-(3-hydroxymethyl)oxetane (EHO).A typical procedure for the polymerization of E...

Hyperbranched aliphatic polyether polyols

“…88,89 They obtained polymers with molecular weights up to 4100 g mol À1 in good yields, but with broad polydispersities (M w /M n ¼ 4.0-5.5). The DB was comparatively low with values between 16% and 27%.…”

Synthesis of Hyperbranched Polymers by the Anionic Ring-Opening Polymerization of 3,3-Bis(hydroxymethyl)oxetane

“…18 In this paper, we examined the synthesis of hyperbranched poly(ether) by the anionic polymerization of BHO, containing two hydroxyl groups (Scheme 2).…”

“…[13][14][15][16][17] More recently, we reported a new anionic ringopening polymerization of EHO and 3-methyl-3-hydroxymethyloxetane (MHO) containing hydroxyl groups using potassium tert-butoxide (t-BuOK) and 18-crown-6-ether (18-C-6), affording the hyperbranched polyether containing an oxetanyl group and many hydroxyl groups at the end (Scheme 1). 18,19 Furthermore, we achieved the synthesis of a pseudo dendritic polymer with many pendant hydroxyl groups by the cationic ring-opening polymerization of the poly(EHO) derivative. 19 These synthesized polymers poly(EHO), poly(MHO), and pseudo dendritic polymers are expected as useful functional materials, because they have many hydroxyl groups at the ends.…”

Synthesis of Hyperbranched Poly(ester)s with Pendant Hydroxy Groups by the Polyaddition of Bis(oxetane)s with 1,3,5-Benzenetricarboxylic Acid

“…These reactions can be applied practically to the polyadditions of bis(oxetane)s with above reagents such as diacyl chlorides, 14-17 phosphonyl dichlorides, 8 active diesters, 18,19 dicarboxylic acids, 10 bisphenols, 11,12 and dithiols 13 to afford corresponding polymers with high molecular weights. Recently, we also found that an anionic ring-opening polymerization of 2-(hydroxymethyl)oxetanes produced corresponding hyperbranched poly(ether)s containing one terminal oxetanyl groups and many pendant primary hydroxy groups using the complex of potassium t-buthoxide with crown ether as a catalyst system, [20][21][22] and an anionic ring-opening alternating copolymerization 23 of oxetanes with cyclic carboxylic anhydrides using certain quaternary onium salts as catalysts.The above reaction systems of oxetane compounds and the oxetane polymers prepared by the reactions seem to have great possibility as an important key technology in coatings and electronics fields, and polymer industry in general.Meanwhile, hyperbranched polymers (HBPs) have recently attracted a great deal of attention as one of the dendritic macromolecules, which have lower viscosity, good solubility and many reactive terminal groups compared with the corresponding linear ones. 24 There are many synthetic methods for the preparation of the HBPs, such as vinyl polymerization 25 and ring-opening polymerization 26 accompanying suitable chain transfer reaction.…”

“…These reactions can be applied practically to the polyadditions of bis(oxetane)s with above reagents such as diacyl chlorides, [14][15][16][17] phosphonyl dichlorides, 8 active diesters, 18,19 dicarboxylic acids, 10 bisphenols, 11,12 and dithiols 13 to afford corresponding polymers with high molecular weights. Recently, we also found that an anionic ring-opening polymerization of 2-(hydroxymethyl)oxetanes produced corresponding hyperbranched poly(ether)s containing one terminal oxetanyl groups and many pendant primary hydroxy groups using the complex of potassium t-buthoxide with crown ether as a catalyst system, [20][21][22] and an anionic ring-opening alternating copolymerization 23 of oxetanes with cyclic carboxylic anhydrides using certain quaternary onium salts as catalysts.…”