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

Abstract

ABSTRACT:The anionic ring-opening polymerization of 3,3-bis(hydroxymethyl)oxetane (BHO) was carried out using t-BuOK as an initiator in the presence of 18-crown-6-ether (18-C-6) in NMP at 180 C, affording the corresponding hyperbranched polyethers, poly(BHO)s containing an oxetanyl group and many hydroxyl groups at the ends in 83-98% yields. Since the resulting poly(BHO)s were insoluble in common organic solvents, the poly(BHO)s were treated with acetic anhydride to obtain poly(BHO-Ac)s containing acetyl groups at the ends. The M n s and degree of branching (DB) of poly(BHO-Ac)s were in the range of 2600-4400 estimated by SEC and 0.09-0.55 calculated by 13 C NMR spectroscopy, respectively. The cationic copolymerization of poly(BHO-Ac) and 3-ethyl-3-phenoxymethyloxetane (EPO) was examined using BF 3 reported the synthesis of hyperbranched polyethers by the cationic ring-opening polymerization of EHO using various cationic initiators. Penczek et al. 4 reported that the cationic ring-opening polymerizations of 3,3-bis(hydroxymethyl)oxetane (BHO), and the copolymerization of BHO with EHO were performed to give medium molecular-weight polymers in good yields.Meanwhile, we have developed many new reactions of oxetanes with various protonic reagents such as phenols, 5 thiophenols, 6 carboxylic acids, 7 and thioesters 8 in the presence of quaternary onium salts or crown ether complexes as catalysts. These new reactions have been applied to the synthesis of polymers such as polyethers, 5 polyesters, 7,9 polyphosphonates, 10 and poly(silyl ether)s. 11 Furthermore, we have found anionic alternating ring-opening copolymerization of oxetanes with carboxylic anhydrides in the presence of the quaternary onium salts as initiators.12 Inoue and Endo et al. preformed the living anionic polymerization of oxetanes using metal complexes as catalysts. [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.In a series of the study for the synthesis of hyperbranched polyether by the anionic ring-opening polymerization of the oxetane with hydroxyl groups in this article, we examined the reaction of BHO containing two hydroxyl groups in the presence of t-BuOK in several conditions in detail. Furthermore, we also examined the reaction of the resulting polymers for the synthesis of new branched polymers containing pendant many hydroxyl groups. EXPERIMENTAL MaterialsThe solvents, chloroform (CHCl 3 ...

Catalytic reactions of oxetanes with protonic reagents and aprotic reagents leading to novel polymers

“…64,68 The wide applications of the synthesized HBPs and pseudo dendritic polymers are expected because of the many pendant hydroxy groups in the side chains (Scheme 8).…”

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.…”

“…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.…”

Synthesis of Poly(ether)s with Pendant Ester Groups by the Polyaddition of Bis(oxetane)s with Active Bis(ester)s

“…Since these addition reactions proceed smoothly without any side reactions even at higher temperatures than those of the reaction of oxiranes, the reactions can be used as suitable reaction for the polymer synthesis. More recently, our research group found anionic ring-opening alternating copolymerization 20 of oxetane with carboxylic anhydride, and anionic ringopening polymerization [21][22][23] of 3-ethyl-3-hydroxymethyloxetane. However, we do not have development of the addition reaction of oxetanes with phenyl esters until now, although we have found the addition reactions of oxetane with acyl chloride [15][16][17][18][19][20][21][22][23][24] or S-aryl thioesters.…”

“…More recently, our research group found anionic ring-opening alternating copolymerization 20 of oxetane with carboxylic anhydride, and anionic ringopening polymerization [21][22][23] of 3-ethyl-3-hydroxymethyloxetane. However, we do not have development of the addition reaction of oxetanes with phenyl esters until now, although we have found the addition reactions of oxetane with acyl chloride [15][16][17][18][19][20][21][22][23][24] or S-aryl thioesters. 26,27 From these backgrounds, in this article, we examined the polyaddition of bis(oxetane)s with active bis(ester)s, which were prepared by the reaction of bis(phenol)s with carboxylic acid derivatives, for the synthesis of poly(ether)s containing pendant ester groups under appropriate reaction conditions.…”