Synthesis of amphiphilic block copolymer by metal‐free ring‐opening oligomerization of glycidyl phenyl ether initiated with tetra‐n‐butylammonium fluoride in the presence of poly(ethylene glycol) monomethyl ether

Metal‐free ring‐opening oligomerization of glycidyl phenyl ether (GPE) initiated with tetra‐n‐butylammonium fluoride (n‐Bu₄NF) (5.0 mol %) was performed in the presence of poly(ethylene glycol) monomethyl ether (PEGM) (5.0, 10, 20 mol %) as a chain transfer agent, by which the resulting polymers having narrow molecular weight distribution (M_w/M_n < 1.2) were obtained in 80–84% yield. Solubility of the obtained polymers in water increased with the increase of amount of PEGM, owing to an increase of number of PEGM‐block‐oligo(GPE) molecules compared to that of oligo(GPE) molecules having FCH₂– group at the initiating end as well as a decrease in degree of oligomerization of oligo(GPE). The PEGM‐block‐oligo(GPE) was isolated by filtration of the polymer aqueous solution, whose number‐average molecular weights determined by NMR spectroscopic analysis were almost consistent to the theoretical values. The PEGM‐block‐oligo(GPE) formed micelles in aqueous media, whose average particle diameter was 58 and 140 nm for the copolymers having a composition of PEGM:GPE = 62:38 and 53:47, respectively. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4451–4458     

Synthesis of end‐functionalized polyethers by phosphazene base‐catalyzed ring‐opening polymerization of 1,2‐butylene oxide and glycidyl ether

For the living ring‐opening polymerization (ROP) of epoxy monomers, the catalytic activity of organic superbases, tert‐butylimino‐tris(dimethylamino)phosphorane, 1‐tert‐butyl‐2,2,4,4,4‐pentakis(dimethylamino)‐2Λ⁵,4Λ⁵‐catenadi(phosphazene), 2,8,9‐triisobutyl‐2,5,8,9‐tetraaza‐1‐phosphabicyclo[3.3.3]undecane, and 1‐tert‐butyl‐4,4,4‐tris(dimethylamino)‐2,2‐bis[tris(dimethylamino)phosphoranylidenamino]‐2Λ⁵,4Λ⁵‐catenadi(phosphazene) (t‐Bu‐P₄), was confirmed. Among these superbases, only t‐Bu‐P₄ showed catalytic activity for the ROP of 1,2‐butylene oxide (BO) to afford poly(1,2‐butylene oxide) (PBO) with predicted molecular weight and narrow molecular weight distribution. The results of the kinetic, post‐polymerization experiments, and MALDI‐TOF MS measurement revealed that the t‐Bu‐P₄‐catalyzed ROP of BO proceeded in a living manner in which the alcohol acted as the initiator. This alcohol/t‐Bu‐P₄ system was applicable to the glycidol derivatives, such as benzyl glycidyl ether (BnGE) and t‐butyl glycidyl ether, to afford well‐defined protected polyglycidols. The α‐functionalized polyethers could be obtained using different functionalized initiators, such as 4‐vinylbenzyl alcohol, 5‐hexen‐1‐ol, and 6‐azide‐1‐hexanol. In addition, the well‐defined cyclic‐PBO and PBnGE were successfully synthesized using the combination of t‐Bu‐P₄‐catalyzed ROP and click cyclization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Solvent‐free ring‐opening polymerization of cyclohexene oxide catalyzed by palladium chloride

In this study, we have for the first time demonstrated that palladium chloride (PdCl₂) is an efficient catalyst for ring‐opening polymerization of cyclohexene oxide in a solvent‐free condition. The polymerization product was in atactic structure, and reaction conditions, such as reaction temperature, time, and catalyst amount, showed effects on polymerization conversion yield, turnover number, and number‐average molecular weight of the resulting poly(cyclohexene oxide). PdCl₂ catalysis follows a cationic ring‐opening mechanism. The polymerization result is highly determined by the chemical structure of the monomers.     

Modification of proline‐based 2,5‐diketopiperazines by anionic ring‐opening polymerization

2,5‐Diketopiperazines (DKPs) are the smallest cyclic dipeptides found in nature with various attractive properties. In this study, we have demonstrated the successful modification of proline‐based DKPs using anionic ring‐opening polymerization (AROP) as a direct approach. Four different proline‐based DKPs with various side chains and increasing steric hindrance were used as initiating species for the polymerization of 1,2‐epoxybutane or ethoxyethyl glycidyl ether in the presence of t‐BuP₄ phosphazene base. The addition of a Lewis acid, tri‐isobutyl aluminum, to the reaction mixture strongly decreased the occurrence of side reactions. Impact of the DKP side‐chain functionalities on molar mass control and dispersity was successfully evidenced. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1008–1016     

Controlled ring‐opening polymerization of propylene oxide catalyzed by double metal‐cyanide complex

A double metal‐cyanide catalyst based on Zn₃[Co(CN)₆]₂ was prepared. This catalyst is very effective for the ring‐opening polymerization of propylene oxide. Polyether polyols of moderate molecular weight having low unsaturation (<0.015 meq/g) can be prepared under mild conditions. The molecular weight of polymer is entirely controlled by a reacted monomer‐to‐initiator ratio. The polymers prepared with stepwise addition of monomer exhibit a narrower molecular weight distribution as compared with those prepared with one‐step addition of monomer. Various compounds containing active hydrogen, except basic compounds and low‐carbon carboxylic acid, may be used as initiators. The reaction rate increases with increasing catalyst amount and decreases with rising initiator concentration. Polymerization involves a rapid exchange reaction between the active species and the dormant species. It was also proven that, to a certain extent, the chain termination of this catalytic system is reversible or temporary. ¹³C NMR analysis showed that the polymer has a random distribution of the configurational sequences and head‐to‐tail regiosequence. It is assumed that the polymerization proceeds via a cationic coordination mechanism. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1142–1150, 2002     

Metal-free synthesis of reactive oligomers by ring-opening oligomerization of glycidyl phenyl ether initiated with tetra-n-butylammonium fluoride in the presence of various protic compounds

Metal-free ring-opening oligomerizations of glycidyl phenyl ether (GPE) were performed with tetra-n-butylammonium fluoride (n-Bu₄NF) as an initiator in the presence of protic compounds (RHs) as chain transfer agents (CTAs). The RHs having pKa between 4.66 and 15.5 enabled to serve as the CTA in this oligomerization system, leading to reactive oligomers with relatively controlled molecular weights having narrow molecular weight distributions bearing functional groups such as alkene, benzyl ether, alkyne, ester and methacrylate groups at initiating end.     

Synthesis and ring‐opening polymerization of macrocyclic (arylene thioether ketone) oligomers

Macrocyclic (arylene thioether ketone) oligomers together with a linear poly(phenylene sulfide ketone) oligomer were synthesized by a one‐step reaction. The macrocycles and linear oligomer were fully characterized by ¹³C‐NMR, H‐NMR, matrix assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS), differential scanning calorimetry (DSC) and FT‐IR. Uncatalyzed, simultaneously ring‐opening polymerization (ROP) of the macrocycles and the mixture of macrocycles and linear oligomer were carried out under dynamic heating conditions. The ROP temperature of the macrocycles decreased upon mixing it with the linear oligomer. The ROP conditions and mechanism were investigated and discussed. The macrocycles and their mixture show potential applications in high temperature adhesives and sealants. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis and ring‐opening polymerization of co‐cyclic(aromatic aliphatic disulfide) oligomers

An effective approach was presented for the synthesis of co‐cyclic(aromatic aliphatic disulfide) oligomers by catalytic oxidation of aromatic and aliphatic dithiols with oxygen in the presence of a copper‐amine catalyst. The aromatic dithiols can be 4,4′‐oxybis(benzenethiol), 4,4′‐diphenyl dithiol, 4,4′‐diphenylsulfone dithiol. The aliphatic dithiols can be 1,2‐ethanedithiol, 2,3‐butanedithiol, 1,6‐hexane dithiol. The co‐cyclic(aromatic aliphatic disulfide) oligomers were characterized by gradient HPLC, MALDI‐TOF‐MS, GPC, ¹H‐NMR, TGA, and DSC techniques. The glass transition temperatures of these co‐cyclics ranged from ?11.3 to 56.6°C. In general, these co‐cyclic(aromatic aliphatic disulfide) oligomers are soluble in common organic solvents, such as CHCl₃, THF, DMF, DMAc. These co‐cyclic oligomers readily underwent free radical ring‐opening polymerization in the melt at 180°C, producing linear, tough and high molecular weight poly(aromatic aliphatic disulfide)s. The glass transition temperatures of these polymers ranged from ?3.7 to 107.8°C that are higher than those of corresponding co‐cyclics. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis and ring‐opening polymerization of macrocyclic aryl ketone oligomers

A series of macrocyclic aryl ketone oligomers were prepared by the reaction of phthaloyl dichloride or isophthaloyl dichloride with various bridge‐linking electron‐rich aromatic hydrocarbons 3a–d under pseudo‐high dilution conditions in the presence of Lewis base via Friedel–Crafts acylation reaction. Detailed structural characterization of these oligomers confirmed the cyclic nature by a combination of MALDI‐TOF‐MS, GPC, and ¹H NMR analyses. These cyclic ketone oligomers have high solubility in organic solvents and the cyclic oligomers derived from phthaloyl dichloride are amorphous. The cyclic ketone oligomers readily undergo anionic ring‐opening polymerization in the melt by using potassium 4,4′‐biphenoxide as the initiator, producing linear, high molecular weight poly(ether ketone)s. Moreover, the isothermal chemorheology of the ring‐opening polymerization of cyclic oligomers 4a and 4b was also investigated. The results show that the shear viscosity of the molten reactive mixture is lower than 10 Pa · S at a constant shear rate of 0.05 rad/sec and increases slowly in the initial stage of ring‐opening polymerization. Copyright © 2009 John Wiley & Sons, Ltd.     

Computational evaluation of radical ring‐opening polymerization

The tendencies of ring‐opening processes in radical ring‐opening polymerizations were evaluated by AM1 and PM3 semi‐empirical calculations and 6‐31G*‐level calculations based on the density functional theory (DFT) B3LYP models. Sixteen cyclic monomers bearing vinyl or exomethylene groups were categorized into ring‐opening and no‐ring‐opening monomers by the evaluation of the differences of the internal energies and the lengths of the cleaving bonds between the ground states of the initial radicals and the activated states in the ring‐opening processes. Although the semi‐empirical calculations not parameterized to radical reactions resulted in the moderate categorization of the ring‐opening monomers, the DFT calculation clearly distinguished the ring‐opening and no‐ring‐opening monomers. The ring‐opening tendencies were also evaluated with the changes in the internal energies throughout the ring‐opening processes, but this method could not group the ring‐opening and no‐ring‐opening monomers clearly. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2827–2834, 2007     

Synthesis of metal‐free poly(1,4‐dioxan‐2‐one) by enzyme‐catalyzed ring‐opening polymerization

To avoid the harmful effects of metallic residues in poly(1,4‐dioxan‐2‐one) (PPDO) for medical applications, the enzymatic polymerization of 1,4‐dioxan‐2‐one (PDO) was carried out at 60 °C for 15 h with 5 wt % immobilized lipase CA. The lipase CA, derived from Candida antarctica, exhibited especially high catalytic activity. The highest weight‐average molecular weight (M_w = 41,000) was obtained. The PDO polymerization by the lipase CA occurred because of effective enzyme catalysis. The water component appeared to act not only as a substrate of the initiation process but also as a chain cleavage agent. A slight amount of water enhanced the polymerization, but excess water depressed the polymerization. PPDO prepared by enzyme‐catalyzed polymerization is a metal‐free polyester useful for medical applications. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1560–1567, 2000     

Anionic ring‐opening polymerization of a five‐membered cyclic urethane derived from d‐glucosamine

The anionic ring‐opening polymerization of a five‐membered cyclic urethane, 2‐amino‐4,6‐O‐benzylidene‐2‐N,3‐O‐carbonyl‐2‐deoxy‐α,d ‐glucopyranoside (MBUG), which was prepared from naturally abundant d ‐glucosamine, was examined. Potassium tert‐butoxide (t‐BuOK) was the most effective initiator among the evaluated bases and produced polyurethane with the Mn of 7800 without any elimination of CO₂. The equimolar reaction of MBUG and t‐BuOK in the presence of CH₃I produced N‐methylated MBUG and suggested that the initiation reaction involves proton abstraction from the NH group. This N‐methylated compound did not undergo the polymerization. Therefore, the mechanism of propagation in the ROP of MBUG should involve the proton abstraction and nucleophilic substitution of the resulting amide anion. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2491–2497     

Anionic ring‐opening polymerization of N‐glycidylphthalimide: Combination of phosphazene base and activated monomer mechanism

Anionic ring‐opening polymerization of glycidyl phthalimide, initiated with alcohol–phosphazene base systems and based on monomer activation with a Lewis acid (iBu₃Al), has been studied. No propagation occurred for initiator: iBu₃Al ratios less or equal to 1:3. For larger Lewis acid amounts, the first anionic ring‐opening polymerizations of glycidyl phthalimide were observed. Polymers were carefully characterized by NMR, MALDI‐TOF mass spectrometry, and size exclusion chromatography and particular attention was given to the detection of eventual transfer or side‐reactions. However, polymer precipitation and transfer reaction to aluminum derivative were detrimental to monomer conversion, polymerization control, and limited polymer chain molar masses. The influence of reaction temperature and solvent on polymer precipitation and transfer reactions was studied and reaction conditions have been optimized leading to afford end‐capped poly(glycidyl phthalimide) with narrow molar mass distributions. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1091–1099     

Polyester from dimethylketene and acetaldehyde: Direct copolymerization and β‐lactone ring‐opening polymerization

Two ways to obtain aliphatic polyesters (PEs) from dimethylketene and acetaldehyde were investigated. On the one hand, a direct anionic copolymerization was carried out in toluene at ?60 °C. The resulting polymer was mainly composed of PE units. On the other hand, a two‐step process involving the synthesis of 3,3,4‐trimethyl‐2‐oxetanone by [2+2] cycloaddition, followed by its ring‐opening polymerization, with various initiators and solvents, led to the expected PE. Molecular weights up to 9000 g mol^?1 (measured by nuclear magnetic resonance (NMR)), with narrow polydispersity around 1.2, were obtained. These polymers were found stable up to 274 °C under nitrogen and a broad and complex endothermic peak attributed to crystallinity was observed near 139 °C by differential scanning calorimetry (DSC). The crystallinity, measured by X‐ray diffraction, was close to 0.45. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Anionic ring‐opening polymerization of a five‐membered cyclic carbonate having a glucopyranoside structure

Anionic ring‐opening polymerizations of methyl 4,6‐O‐benzylidene‐2,3‐O‐carbonyl‐α‐D ‐glucopyranoside (MBCG) were investigated using various anionic polymerization initiators. Polymerizations of the cyclic carbonate readily proceeded by using highly active initiators such as n‐butyllithium, lithium tert‐butoxide, sodium tert‐butoxide, potassium tert‐butoxide, and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene, whereas it did not proceed by using N,N‐dimethyl‐4‐aminopyridine and pyridine as initiators. In a polymerization of MBCG (1.0 M), 99% of MBCG was converted within 30 s to give the corresponding polymer with number‐averaged molecular weight (M_n) of 16,000. However, the M_n of the polymer decreased to 7500 when the polymerization time was prolonged to 24 h. It is because a backbiting reaction might occur under the polymerization conditions. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Do‐it‐yourself functionalized silicones part 2: synthesis by ring opening polymerization of commercial cyclosiloxanes

The second paper of the series devoted to the preparation and characterization of vinyl and hydrido‐functionalized silicones proposes readily available techniques to polymerize commercially available cyclosiloxanes. This study is divided into two main sections: one relies on the synthesis of various functional silicone oils by heterogeneous cationic ring opening polymerization (ROP) of cyclotetrasiloxanes (D₄, D) and appropriate 1,3‐difunctional disiloxanes; the second part describes the anionic ROP of hexamethylcyclotrisiloxane (D₃) initiated by potassium silanolates to prepare both homo‐ and hetero‐vinyl functionalized silicones. The conditzions in which polymers with desired molecular weights can be obtained have been established and some kinetic considerations are also reported. The width of the final molar mass distribution ranged between 1.5 and 1.8, respectively, in any case narrower than the mixtures proposed by different providers (around 2). Polymers were characterized by different techniques of size exclusion chromatography (SEC), proton and silicon nuclear magnetic resonance (¹H and ²⁹Si NMR), and mass spectrometry. Copyright © 2009 John Wiley & Sons, Ltd.