Cationic Polymerization Of Tetrahydrofuran Research Articles

Synthesis of block copolymers through umpolung or treatment of propagating end of living cationic polytetrahydrofuran

Block copolymers containing polytetrahydrofuran segments were synthesized by umpolung or propagating end of the cationic living polymer and successive anionic polymerization of methacrylates (RMAs) or radical polymerization of RMAs, acrylonitrile (AN), and styrene (St). Living polytetrahydrofuran (poly-THF) was prepared by cationic polymerization of tetrahydrofuran (THF), whose propagation end was reduced by samarium(II) iodide (SmI2). Anionic polymerizations of RMAs were conducted by addition of the monomers to the reduced poly-THF to obtain poly(THF-b-RMAs). On the other hand, the 2-bromoisobutyrate group, which can act as an initiator of radical polymerization, was introduced to the cationic propagating end of poly-THF by adding sodium 2-bromoisobutyrate. Block copolymers were synthesized by living radical polymerization of RMAs, St, or AN using the 2-bromoisobutyrate-capped poly-THF as a macroinitiator and copper(I) bromide (CuBr) as a catalyst.

Dormant Polymers and Their Role in Living and Controlled Polymerizations; Influence on Polymer Chemistry, Particularly on the Ring Opening Polymerization.

Living polymerization discovered by Professor Szwarc is well known to all chemists. Some of the living polymerizations involve dormancy, a process in which there is an equilibrium (or at least exchange) between two types of living polymers, namely active at the given moment and dormant at this moment and becoming active in the process of activation. These processes are at least equally important although less known. This mini review is devoted to these particular living polymerizations, mostly polymerizations by the Ring-Opening Polymerization mechanisms (ROP) compared with some selected close to living vinyl polymerizations (the most spectacular is Atom Transfer Radical Polymerization (ATRP)) involving dormancy. Cationic polymerization of tetrahydrofuran was the first one, based on equilibrium between oxonium ions (active) and covalent (esters) dormant species, i.e., temporarily inactive, and is described in detail. The other systems discussed are polymerization of oxazolines and cyclic esters as well as controlled radical and cationic polymerizations of vinyl monomers.

Synthesis of novel tetrahydrofuran-epichlorohydrin [poly(THF-b-ECH)] macromonomeric peroxy initiators by cationic copolymerization and the quantum chemically investigation of initiation system effects

Cationic polymerization of tetrahydrofuran (THF) and epichlorohydrin (ECH) was performed with peroxy initiators synthesized from bis (4,4′-bromomethyl benzoyl peroxide (BBP) or bromomethyl benzoyl t-butyl peroxy ester (t-BuBP) and AgSbF6 or ZnCl2 system at 0 °C to obtain the poly(THF-b-ECH) macromonomeric peroxy initiators. Kinetic studies were accomplished for poly(THF-b-ECH) initiators. Poly(THF-b-ECH-b-MMA) and poly(THF-b-ECH-b-S) block copolymers were synthesized by bulk polymerization of methyl methacrylate (MMA) and styrene (S) with poly(THF-b-ECH) initiators. The quantum chemical calculations for the block copolymers, the initiating systems of the cationic polymerization of THF and ECH were achieved using HYPERCHEM 7.5 program. The optimized geometries of the polymers were investigated with the quantum chemical calculations. Poly(THF-b-ECH) initiators having peroxygen groups were used for graft copolymerization of polybutadien (PBd) to obtain poly(THF-b-ECH-g-PBd) crosslinked graft copolymers. The graft copolymers were investigated by sol-gel analysis. Swelling ratio values of the graft copolymers in CHCl3 were calculated. The characterizations of the polymers were achieved by FTIR, 1H NMR, GPC, SEM, TEM, and DSC techniques. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2896–2909, 2010

Preparation of the supported heteropolyacids catalyst by ultrasound-plasma treatment

Novel catalysts of phosphotungstic heteropolyacids (PW12) supported on neutral alumina were prepared by assistance of ultrasound and plasma treatment. The prepared catalysts were characterized by FT-IR pyridine adsorption (Py-IR), temperature programmed desorption of Pyridine (Py-TPD), BET and X-ray diffraction (XRD), and their catalytic performances were evaluated by the cationic polymerization of tetrahydrofuran. The results indicate that plasma treatment remarkably increases the surface acidity of the prepared catalyst while ultrasonic treatment induces PW12 to uniformly disperse on the support surface and expose more active sites for the acid catalytic reaction. A higher catalytic activity (69.7%) is obtained on the novel catalyst, which significantly outstripped that on the conventional sample (57.5%).

Grafting on polybutadiene with polytetrahydrofuran macroperoxyinitiators. Postpolymerization studies

Grafting reactions of polybutadiene with macro peroxy initiators and postpolymerization were studied. The cationic polymerization of tetrahydrofuran (THF) initiated by the cationic species derived from bis-(4-bromomethylbenzoyl) peroxide (BBP) or bis-(3,5-dibromomethylbenzoyl) peroxide (BDBP) gave the PTHF macroperoxy initiator (MPI). PTHF- b-PMMA macroperoxy initiator (MPIb) was also obtained by the redox polymerization of methyl methacrylate initiated with the hydroxyl ends of PTHF and Ce(IV) salts without decomposing the peroxide groups in the middle. Macroperoxy initiators thermally grafted on cis-polybutadiene (PBD) with thermal curing to yield graft copolymers containing crosslinked and soluble parts, which were separated by the sol–gel analysis. FTIR spectra of the crosslinked samples indicated the characteristic signals of the PTHF, PBD and PMMA blocks. The crosslinked copolymers decomposed at around 470 °C. Postpolymerization of the crosslinked products indicated the increase in crosslinking density which has been followed by measuring the gradual increase of swelling values. Postpolymerization crosslinking was estimated as a first order reaction rate.

Initiation system effects in the cationic copolymerization of tetrahydrofuran (THF)

Macromonomeric peroxy initiator, poly tetrahydrofuran (poly-THF=inimer) were synthesized via cationic polymerization of THF by the mono- (t-BuBP) and tetra-bromo methyl benzoyl peroxides (BDBP)/ZnCl 2 initiating system. The macromonomers were characterized by 'H-NMR, IR, and GPC techniques. Methyl methacrylate (MMA) polymerization initiated by poly-THF inimers at 80°C and different times in bulk gave crosslinked poly-THF-b-polymethyl methacrylate block copolymers. Swelling ratios of the crosslinked block copolymers obtained by taking in same amounts of poly-THF inimer and MMA monomer in CHCl 3 were decreased versus time. It was compared the results obtained from t-BuBP-, BDBP-ZnCl 2 initiating systems with t-BuBP-, BDBP-AgSbF 6 initiating systems for THF monomer. Poly(THF-b-MMA) crosslinked block copolymers containing undecomposed peroxide groups initiated the thermal polymerization of styrene , S, were used to obtain poly(THF-b-MMA-b-S) crosslinked multicomponent copolymers at 90°C. The crosslinked multi component copolymers were investigated sol-gel analysis and swelling ratios in CHCl 3 . Active poly(THF-b-MMA) having peroxygen group were used in the free radical coupling reaction of poly butadien (Poly Bd). Poly(THF-b-MMA)-polybutadien crosslinked blend soluble graft copolymers were obtained.

Synthesis of a Star-Shaped Copolymer with a Hyperbranched Poly(3-methyl-3-oxetanemethanol) Core and Tetrahydrofuran Arms by One-Pot Copolymerization

A star-shaped copolymer consisting of a hyperbrached poly(3-methyl-3-oxetanemethanol) core and polytetrahydrofuran arms was obtained by a one-step cationic copolymierization of 3-methyl-3-oxetanemethanol with tetrahydrofuran initiated by BF 3 .OEt 2 . Tetrahydrofuran served as a solvent at the earliet stage of the polymerization. After 3-methyl-3-oxetanemethanol exhausted essentially, the resulting hyperoranched species acted as a macro-initiator, and initiated the cationic polymerization of tetrahydrofuran. This can be attributed to the large difference in reactivities of the monomers.

Polymerization of methyl methacrylate and other polar monomers with alkylaluminum initiators bearing bidentate and tridentate N‐ and O‐donor ligands

AbstractDimethylaluminum complexes bearing bidentate amidate, oxypyridine, and salicylaldimine N,O‐ligands and tridentate N,N′,N″‐pyridyliminoamide ligands were synthesized and spectroscopically characterized. The complexes were investigated in both neutral and borane‐activated cationic forms, along with bidentate N,N′‐ligated aluminum amidinates, as catalysts for the polymerization of methyl methacrylate, ϵ‐caprolactone, and propylene oxide. The neutral complexes generally did not carry out polymerization, but the polymerization/oligomerization of all three monomers was achieved when the various catalysts were activated with B(C6F5)3 or [Ph3C]+[B(C6F5)4]−. The N,O‐ligated cations were much less active for polymerization than the analogous, more stable N,N′‐ligated amidinate cations; both types of cationic complexes catalyzed the ring‐opening cationic polymerization of tetrahydrofuran. B(C6F5)3 and [Ph3C]+[B(C6F5)4]− also independently carried out the oligomerization of propylene oxide. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1633–1651, 2002

One-pot synthesis and characterization of aliphatic poly(oxytetramethylene) ionene

One-pot synthesis of poly(oxytetramethylene) ionene (POI) composed of one dimethylammonium group in each repeating unit is described. POI was prepared by using the cationic polymerization of tetrahydrofuran, followed by the chain extension reaction of living poly(oxytetramethylene) (POTM) chain with N, N-dimethylaminotrimethylsilane. The weight average molecular weight of the ionene with bromide counter-anion (POI–Br) was 48,000 g/mol and the molecular weight of POTM between the ionic sites was ca. 2100. POI–Br showed polyelectrolyte behavior in polar solvent. The elastomeric film of POI–Br was prepared: its tensile strength at break and elongation at break were ca. 11 MPa and ca. 1900% at 19 °C, respectively. Small-angle X-ray scattering, differential scanning calorimetry and dynamic mechanical analysis suggested the formation of microphase-separated structure for POI–Br film.

The Synthesis of Liquid Crystalline Copolymers with Block Copolymer Grafts

The synthesis of novel copolymers consisting of a side-group liquid crystalline backbone and poly(tetrahydrofuran)-poly(methyl methacrylate) block copolymer grafts was realized by using cationic-to-free-radical transformation reactions. Firstly, photoactive poly(tetrahydrofuran) macroinimers were prepared by cationic polymerization of tetrahydrofuran and subsequent termination with 2-picoline N-oxide. Secondly, the macroinimers and acrylate monomers containing different spaced cyanobiphenyl mesogenic groups were copolymerized to yiel the respective graft copolymers. Eventually, these were used for indirect photochmical polymerization of methyl methacrylate by UV irradiation in the presence of anthracene as a photosensitizer leading ti the final copolymers with block copolymer grafts. The liquid crystalline, semi-crystalline, and amorphous blocks were micro-phase separated in the graft copolymers.

Photo-induced living cationic polymerization of tetrahydrofuran. III. Synthesis of poly(THF-co-3-MTHF)

Poly(3-methyltetrahydrofuran)(3-MTHF) and poly(tetrahydrofuran-co-3-MTHF), having very narrow molecular weight distribution were successfully synthesized via photo-induced living cationic polymerization in the presence of diphenyliodonium hexafluorophosphate. Linear relationship between % conversion and number average molecular weight of resulting poly(3-MTHF) in the polymerization of 3-MTHF, carried out at −22°C, indicates that the 5-membered cyclic oxonium ion, being responsible for the cationic propagation is stabilized by ion pair formation with hexafluorophosphate anion, supplied from the salt. The linear relationship between two parameters, mentioned above was also observed in the copolymerization of 3-MTHF with THF, carried out at 0 and −22°C. The molecular structures including the copolymer composition and average molecular weight and its distribution is determined by reaction parameters such as monomer feed ratio and reaction temperature.

新しいポリウレタンカチオノマー 第１報 末端セグメントにイオン点を有するプレポリマーから合成したポリウレタンカチオノマー

Hydroxy-terminated poly(oxytetramethylene) with ionic sites in the end of segments (HA-PT) was synthesized by the cationic polymerization of tetrahydrofuran using (CF3SO2)2O at 0°C and the termination reaction by using excess of 2-dimethylaminoethanol for a polyurethane synthesis. The molecular weight of HA-PT was ca. 2300. Toluene-2, 4-diisocyanate (TDI) was slowly reacted with HA-PT in dimethyl sulf oxide at 90°C. The obtained polyemr (PUC) was confirmed to be a new polyurethane cationomer by Fourier-transform infrared spectroscopy, i.e., the cationic site existed between the polyether and urethane linkage in PUC. The PUC film prepared by casting from the methanol solution of PUC was an elastomer.

Synthesis and Characterization of Poly(oxytetramethylene) Ionene with 2,2‘-Bipyridinium Units

A novel ionene elastomer (DPI) consisting of 2,2‘-bipyridinium units and poly(oxytetramethylene) (POTM) segments was synthesized by cationic polymerization of tetrahydrofuran followed by termination using 2,2‘-bipyridine. The molecular mass between the ionic sites was ca. 10 000 g/mol. The DPI film displayed a high tensile strength up to 34 MPa and 540% elongation at break at 25 °C. The higher-order structure of the DPI film was investigated by thermal and dynamic mechanical analyses and by wide-angle X-ray diffraction and small-angle X-ray scattering (SAXS) measurements. The DPI film had a microphase-separated structure consisting of three phases of the POTM amorphous matrix, the POTM crystalline domain and the ionic domain at room temperature. The POTM crystalline domain was lamellar, and its spacing was ca. 270 A. A new model was proposed to successfully account for the upturn of the scattering intensity toward zero angle in the SAXS profile of DPI at 65 °C, where two phases of the POTM amorphous matri...

Synthesis of tetrahydrofuran‐styrene and tetrahydrofuran‐methyl methacrylate block copolymers via poly(tetrahydrofuran) with azo groups

AbstractThe cationic polymerization of tetrahydrofuran (THF) initiated by 4,4′‐azobis(4‐cyanopentanoyl chloride) (ACPC) and SnCI4 is described. Poly(THF) samples possessing azo gorups in the main chain thus obtained were used as initiator in the polymerization of styrene (S) and methyl methacrylate (MMA) at 70°C to yield PTHF‐PS‐PTHF and PTHF‐PMMA block copolymers. Characterization of the block copolymers was carried out by fractional precipitation, spectroscopic methods and viscosity measurements.

Using Epitaxy To Form Insoluble, Ultrathin Films of Block Copolymers

A new method of assembling functional films by epitaxy of diblock copolymers is reported. The fundamental architecture consists of a crystalline block that is used to tether the whole chain onto a substrate surface by epitaxial adsorption, and a noncrystalline block that provides functional groups. Epitaxial adsorption is realized by polymerization-induced epitaxy, where solution polymerization of monomers directly induces epitaxial growth of chains on the substrate surface. After cationic polymerization of tetrahydrofuran (THF) with the presence of graphite in a reaction mixture, a mixture of THF and 3,3-bis(chloromethyl)oxacyclobutane (BCMO) were introduced to the reaction mixture to form PTHF-block-P(THF-BCMO). Fourier transformed infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the presence of the block copolymer on graphite even after rigorous rinsing of the substrate surface. Atomic force microscopy scanned over micrometer ranges exhibited the same island features as that of PTHF homopolymer film. But these crystalline islands are covered by ultrathin, highly viscous layers that are insoluble. Molecular resolution images by scanning tunneling microscopy showed that the features on the copolymer film are the same as that of an epitaxially adsorbed monolayer of PTHF homopolymer. No film remained on the graphite surface if the graphite was simply immersed in the copolymer solution and was rinsed similarly. These results indicate that the insoluble film of diblock copolymer was formed during polymerization, in which the crystalline PTHF block binds to the surface by epitaxial adsorption and the noncrystalline P(THF-BCMO) block is free of surface attachment.

Trimethylsilyl triflate as an initiator for cationic polymerization: Improved initiation through the use of promoters

AbstractTrimethylsilyl triflate (TMSOTf) can be used as an initiator for the cationic polymerization of alkenes and heterocycles. However, TMSOTf without additives and promoters acts inefficiently. Initiation in the cationic polymerization of tetrahydrofuran is slow because of unfavorable charge distribution in the trimethylsilyltetrahydrofuranium cation—a product of the reaction of monomer with TMSOTf. Acetone, 1,3‐dioxolane, and 1,2‐propylene oxide have been used as promoters to react with TMSOTf to create more reactive initiating species and to improve efficiency of initiation. Of these promoters, 1,2‐propylene oxide has been the most successful. When TMSOTf has been used to initiate the polymerization of 2‐methyl‐2‐oxazoline, unfavorable charge distribution in the N‐trimethylsilyl‐2‐methyl‐2‐oxiranium cation has produced an unreactive imine dimeric cation which extends the time required for polymerization to several weeks. 1,2‐Propylene oxide has been utilized to prevent formation of the imine dimeric cation by producing a more reactive initiating species. In the polymerization of isobutyl vinyl ether initiated by TMSOTf, 1,2‐propylene oxide has been shown to be ineffective as a promoter, but acetone can be used successfully. © 1995 John Wiley & Sons, Inc.

Synthesis of hybrid liquid crystalline block copolymers by combination of cationic or promoted cationic and free-radical polymerizations

The synthesis of two new classes of liquid crystalline block copolymers (1–5) by a two-step combination of cationic and free-radical polymerizations is described. An azomacroinitiator was prepared first by cationic polymerization of tetrahydrofuran or promoted cationic polymerization of cyclohexene oxide, which was then used to initiate the free-radical polymerization of an acrylate monomer containing a variously substituted biphenyl mesogenic group. The semicrystalline and liquid crystalline blocks were essentially microphase-separated and gave rise to different thermotropic mesophases.

Thermodynamic Recycling—On Ring-Opening Polymerization and Ring-Closing Depolymerization

Abstract The ring-opening polymerization of various cyclic monomers has been extensively investigated in the past, e.g., the cationic polymerization of tetrahydrofuran, the anionic polymerization of ∊-caprolactone, the metathesis polymerization of cycloalkenes, and the anionic or cationic polymerization of cyclohexamethyltrisiloxane and cyclooctamethyltetrasiloxane. In conjunction with ring–opening polymerization, monomer–polymer equilibrium (ceiling temperature) and/or the formation of a ring–chain equilibrium have also been studied. In the last few years we have studied extensively the anionic ring-opening polymerization and copolymerization of cyclic carbonates, the monomers mostly being provided by depolymerization of the polymers which were obtained by polycondensation polymerization. This fact has led to the development of a new polymer recycling concept by depolymerization and repolymerization, which we call thermodynamic recycling.

Hydrophilic elastomer containing poly(tetrahydrofuran) segments and viologen units

AbstractElastomeric polymer consisting of poly(oxytetramethylene) segments and viologen units was prepared by living cationic polymerization of tetrahydrofuran (THF), followed by the end capping of the living polymer by 4,4´‐bipyridine. The obtained ionene‐type polymer (PTV) exhibited low tensile modulus and high tensile strength with large extensibility, i.e., it is an excellent elastomer from its mechanical properties. The water swelling behavior and effects of water and the sort of counter anions on the tensile properties of PTV were investigated. PTV showed high hydrophilicity; e.g., the water content of PTV with bromide counter anions was ca. 40% after swelling in water at 25°C for 24 h. However, even for the samples with such a high water content, PTVs displayed good elastomeric properties, although the tensile modulus and tensile strength were decreased with increase of water content. The hydrophilicity of PTV was found to depend on the kind of counter anions, which in turn determined the tensile properties of PTVs in a swollen state.

Mechanistic and kinetic studies on the photoinitiated polymerization of tetrahydrofuran

AbstractPolymerization of tetrahydrofuran (THF) (bulk) promoted by a free radical source, 2,2‐dimethoxy‐2‐phenyl acetophenone (DMPA), in the presence of 4,4′‐di‐(methylphenyl)iodonium hexafluorophosphate was studied in detail. Rate dependence of the polymerizing system on both DMPA and the iodonium salt was studied dilatometrically. Rate saturation for the iodonium salt was attributed to the formation of iodobenzene, which may react with propagating cations to form an iodonium salt. DMPA was shown to be an efficient transfer agent in the cationic polymerization of THF. A transfer constant for DMPA was estimated to be 2.8 and, whilst the precise details of the overall mechanism cannot be deduced from the present results, it may result in functionalized polytetrahydrofuran chains having photochemically active end groups.