Organocatalyzed ring‐opening polymerization of cyclic butylene terephthalate oligomers

In this study, various organic compounds, with different activation modes, have been tested as catalysts for the ring‐opening polymerization (ROP) of cyclic butylene terephthalate oligomers (CBT) in bulk at 210 °C, using tert‐butylbenzyl alcohol (tBnOH) as initiator. Among them, 1,3,5‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) appeared to be the most efficient, achieving high monomer conversions in short reaction times (within minutes). Analysis by size‐exclusion chromatography (SEC) of the poly(butylene terephthalate) (PBT) synthesized using this catalyst also showed that the polymerization follows the expected theoretical M _n trend for molecular weights up to 50 kg·mol^?1. Chain‐end fidelity relatively to the alcohol initiator has been confirmed by MALDI‐TOF mass spectroscopy, which showed that all polymer chains possess the tert‐butylbenzyl moiety as chain‐end. Finally, to demonstrate the potential of this system for the synthesis of PBT‐based block copolymers, a monomethyl ether poly(ethylene glycol) (PEG) of 5000 g·mol^?1 has been employed as initiator for the ROP of CBT. A PEO‐b‐PBT block copolymer of 15,000 g·mol^?1 could thus been obtained, as confirmed by the shift of the SEC traces towards higher molecular weights and the same diffusion coefficient determined for ¹H NMR signals of the PEO block and the PBT block. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1611–1619     

Characterization of PBT/POSS nanocomposites prepared by in situ polymerization of cyclic poly(butylene terephthalate) initiated by functionalized POSS

Novel poly(butylene terephthalate) (PBT)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites were synthesized by ring‐opening polymerization of cyclic poly(butylene terephthalate) initiated by functionalized POSS with various feed ratios. The impact of POSS incorporation on melting and crystallization behaviors of PBT/POSS nanocomposites was investigated by means of X‐ray diffraction and differential scanning calorimetry. It was found that the novel organic–inorganic association result in the significant alterations in the melting and crystallization behavior of PBT. Thermal studies confirmed that the incorporation of POSS can enhance the thermal stability of the polymers, and the copolymer glass transition temperature increased with the increasing of POSS macromonomer content. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1853–1859, 2010     

Synthesis,characterization, and ring opening polymerization of poly(1,4‐cyclohexylenedimethylene terephthalate) cyclic oligomers

Cyclic oligomers of poly(1,4‐cyclohexylenedimethylene terephthalate) (PCT) were prepared by reaction of 1,4‐cyclohexanedimethanol (CHDM) with terephthaloyl chloride under diluted conditions and separated from the linear products by silica gel column at a yield of 23.7 wt %. Cyclic dimer, trimer, tetramer, pentamer, and hexamer were further separated by high performance liquid chromatography, and found to constitute 98% of the cyclics mixtures. The structures of PCT cyclics were confirmed by means of mass spectrometry, Fourier transform infrared, and ¹H NMR analysis. A series of experiments were carried out to study the effects of catalysts and cis/trans configuration of isomers of CHDM on the yield of cyclic oligomers. Ring opening polymerization of the cyclic oligomers was carried out by heating the sample mixtures at 310 °C for 30 min in the presence of antimony oxide. Polymerization was confirmed by inherent viscosity changes and infrared spectra of the resulting polyesters. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1828–1833, 2000     

A modulated dsc study on the in situ polymerization of cyclic butylene terephthalate oligomers

The polymerization of a cyclic butylene terephthalate (CBT) oligomer was studied as a function of temperature (T=200 and 260°C, respectively) by modulated DSC (MDSC). The first heating was followed by cooling after various holding times (5, 15 and 30 min) prior to the second heating which ended always at T=260°C. This allowed us to study the crystallization and melting behavior of the resulting polybutylene terephthalate (PBT), as well. In contrary to the usual belief, the CBT polymerization is exothermic and the related process is superimposed to that of the CBT melting. The melting behavior of the PBT was affected by the polymerization mode (performed below or above the melting temperature of the PBT product) of the CBT. Annealing above the melting temperature of PBT yielded a product featuring double melting. This was attributed to the presence of crystallites with different degrees of perfection. The crystals perfection which occurred via recrystallization/remelting was manifested by a pronounced exothermic peak in the non-reversing trace.     

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     

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.     

Poly(γ‐benzyl‐L‐glutamate)‐functionalized single‐walled carbon nanotubes from surface‐initiated ring‐opening polymerizations of N‐carboxylanhydride

Single‐walled carbon nanotubes (SWCNTs) have been functionalized with poly(γ‐benzyl‐L ‐glutamate) (PBLG) by ring‐opening polymerizations of γ‐benzyl‐L ‐glutamic acid‐based N‐carboxylanhydrides (NCA‐BLG) using amino‐functionalized SWCNTs (SWCNT‐NH₂) as initiators. The SWCNT functionalization has been verified by FTIR spectroscopy and transmission electron microscopy. The FTIR study reveals that surface‐attached PBLGs adopt random‐coil conformations in contrast to the physically absorbed or bulk PBLGs, which exhibit α‐helical conformations. Raman spectroscopic analysis reveals a significant alteration of the electronic structure of SWCNTs as a result of PBLG functionalization. The PBLG‐functionalized SWCNTs (SWCNT‐PBLG) exhibit enhanced solubility in DMF. Stable DMF solutions of SWCNT‐PBLG/PBLG with a maximum SWCNTs concentration of 259 mg L^?1 can be readily obtained. SWCNT‐PBLG/PBLG solid composites have been characterized by differential scanning calorimetry, thermogravimetric analysis, wide/small‐angle X‐ray scattering (W/SAXS), scanning electron microscopy, and polarized optical microscopy for their thermal or morphological properties. Microfibers containing SWCNT‐PBLG and PBLG can also be prepared via electrospinning. WAXS characterization reveals that SWCNTs are evenly distributed among PBLG rods in solution and in the solid state where PBLGs form a short‐range nematic phase interspersed with amorphous domains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2340–2350, 2010     

Synthesis and Characterization of Poly（butylene adipate-co-terephthalate） Catalyzed by Rare Earth Stearates

Rare earth （Nd, Y, La, Dy） stearates have been synthesized and used as single component catalysts for the polycondensation of dimethyl terephthalate, adipic acid and 1,4-butanediol for the first time preparing biodegradable poly（butylene adipate-co-terephthalate） （PBAT） with high molecular weight, The microstructures of PBAT were characterized by ^1H NMR spectra. The PBAT exhibits good mechanical properties such as high tensile strength （ca. 20 MPa） and long break elongation （〉700%）.     

Preparation of functionalized block copolymers based on a polysiloxane backbone by anionic ring‐opening polymerization

Polysiloxane diblock copolymers containing a pure polysiloxane backbone were prepared by the functionalization of poly(dimethylsiloxane)‐b‐poly(methylvinylsiloxane) copolymers. The copolymers were obtained by the sequential anionic copolymerization of either 1,3,5,7‐tetramethyl‐1,3,5,7‐tetravinylcyclotetrasiloxane or 1,3,5‐trimethyl‐1,3,5‐trivinylcyclotrisiloxane with hexamethylcyclotrisiloxane. The two vinyl monomers showed large differences in the propagation rates, but both could be used for the formation of polysiloxane block copolymers. Differences in the polymerization sequences were investigated and revealed that better control was obtained if the slower propagating monomer was polymerized first. The method permitted the synthesis of block copolymers with molecular weight distributions around 1.4 and lower and high block purities. The vinyl groups of the block copolymers were quantitatively and selectively functionalized by hydrosilation or epoxidation reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1539–1551, 2002     

Microwave‐assisted ring‐opening polymerization of p‐dioxanone

The ring‐opening polymerization (ROP) of p‐dioxanone (PDO) under microwave irradiation with triethylaluminum (AlEt₃) or tin powder as catalyst was investigated. When the ROP of PDO was catalyzed by AlEt₃, the viscosity‐average molecular weight (M_v) of poly(p‐dioxanone) (PPDO) reached 317,000 g mol^?1 only in 30 min, and the yield of PPDO achieved 96.0% at 80 °C. Tin powder was successfully used as catalyst for synthesizing PPDO by microwave heating, and PPDO with M_v of 106,000 g mol^?1 was obtained at 100 °C in 210 min. Microwave heating accelerated the ROP of PDO catalyzed by AlEt₃ or tin powder, compared with the conventional heating method. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3207–3213, 2008     

Rapid ring‐opening polymerization of 1,4‐dioxan‐2‐one initiated by titanium alkoxides

Ring‐opening polymerization of 1,4‐dioxan‐2‐one in bulk was initiated by three titanium alkoxides, titanium dichlorodiisopropoxide (TiCl₂(OiPr)₂), titanium chlorotriisopropoxide (TiCl(OiPr)₃), and titanium tetraisopropoxide (Ti(OiPr)₄). The results indicate that the polymerization rate increased with number of OiPr groups in the initiator. High conversion of monomer (90%) and high molecular weight (11.9 × 10⁴ g/mol) of resulting polymer can be achieved in only 5 min at 60 °C with Ti(OiPr)₄ as an initiator. Analysis on nuclear magnetic resonance (NMR) spectra suggests the initiating sites for TiCl₂(OiPr)₂, TiCl(OiPr)₃, and Ti(OiPr)₄ to be 1.9, 2.6, and 3.8, respectively. Coordination‐insertion mechanism for the polymerization via cleavage of the acyl–oxygen bonds of the monomer was proved by NMR investigation. Kinetic studies indicate that polymerization initiated by Ti(OiPr)₄ followed a first‐order kinetics, with an apparent activation energy of 33.7 kJ/mol. It is noteworthy that this value is significantly lower than earlier reported values with other catalysts, namely La(OiPr)₃ (50.5 kJ/mol) and Sn(Oct)₂ (71.8 kJ/mol), which makes it an attractive catalyst for reactive extrusion polymerization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

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.     

Radical ring‐opening polymerization

The radical ring‐opening polymerization (RROP) behavior of the following monomers is reviewed, and the possibility for application to functional materials is described: cyclic disulfide, bicyclobutane, vinylcyclopropane, vinylcyclobutane, vinyloxirane, vinylthiirane, 4‐methylene‐1,3‐dioxolane, cyclic ketene acetal, cyclic arylsulfide, cyclic α‐oxyacrylate, benzocyclobutene, o‐xylylene dimer, exo‐methylene‐substituted spiro orthocarbonate, exo‐methylene‐substituted spiro orthoester, and vinylcyclopropanone cyclic acetal. RROP is a promising candidate for producing a wide variety of environmentally friendly functional polymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 265–276, 2001     

Bis(4‐nitrophenyl) phosphate as an efficient organocatalyst for ring‐opening polymerization of β‐butyrolactone leading to end‐functionalized and diblock polyesters

The ring‐opening polymerization (ROP) of β‐butyrolactone (β‐BL) has been studied using the organocatalysts of diphenyl phosphate (DPP) and bis(4‐nitrophenyl) phosphate (BNPP). The controlled ROP of β‐BL was achieved using BNPP, whereas that of using DPP was insufficient because of its low acidity. For the BNPP‐catalyzed ROP of β‐BL, the dual activation property for β‐BL and the chain‐end models of poly(β‐butyrolactone) (PBL) were confirmed by NMR measurements. The optimized polymerization condition for the ROP of β‐BL proceeded through an O‐acyl cleavage to produce the well‐defined PBLs with molecular weights up to 10,650 g mol^?1 and relatively narrow polydispersities of 1.19–1.39. Functional initiators were utilized for producing the end‐functionalized PBLs with the ethynyl, maleimide, pentafluorophenyl, methacryloyl, and styryl groups. Additionally, the diblock copolymers consisting of the PBL segment with the polyester or polycarbonate segments were prepared by the BNPP‐catalyzed ROPs of ε‐caprolactone or trimethylene carbonate without quenching. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2032–2039     

New Strategy for Enzymatic Synthesis of High‐Molecular‐Weight Poly(butylene succinate) via Cyclic Oligomers

Summary: High‐molecular‐weight poly(butylene succinate) (PBS) is prepared by the lipase‐catalyzed polymerization of dimethyl succinate and butane‐1,4‐diol via the formation of cyclic oligomers as a new strategy for the green production of bio‐based plastics. The cyclic oligomer is first produced by the lipase‐catalyzed condensation of dimethyl succinate and butane‐1,4‐diol in a dilute toluene solution using lipase from Candida antarctica, followed by the ring‐opening polymerization of the cyclic oligomer in a more concentrated solution or in bulk with the same lipase to produce PBS with an of 130 000. On the other hand, PBS is produced with an of 45 000 by direct polycondensation.

The lipase‐catalyzed preparation of PBS by two routes.     

Morphology and thermal properties of poly(L‐lactide)/poly(butylene succinate‐co‐butylene adipate) compounded with twice functionalized clay

Poly(L ‐lactide) (PLLA)/poly(butylene succinate‐co‐butylene adipate) (PBSA) blends were compounded with Cloisite 25A® (C25A) and C25A functionalized with epoxy groups, respectively. Epoxy groups on the surface of C25A were introduced by treating C25A with (glycidoxypropyl)trimethoxy silane (GPS) to produce so called Twice Functionalized Organoclay (TFC). Variation of morphology and properties of PLLA/PBSA/C25A composites was investigated before and after the treatment with GPS. The morphological structure of the composites was analyzed by using X‐ray diffractometry (XRD) and transmission electron microscopy (TEM). The silicate layers of PLLA/PBSA/TFC were exfoliated to a larger extent than PLLA/PBSA/C25A. Incorporation of the epoxy groups on C25A improved significantly elongation at break as well as tensile modulus and tensile strength of PLLA/PBSA/C25A. The larger amount of exfoliation of the silicate layers in PLLA/PBSA/TFC as compared with that in PLLA/PBSA/C25A was attributed to the increased interfacial interaction between the polyesters and the clay due to chemical reaction. Thermo gravimetric analysis revealed that both T_5%, which was the temperature corresponding to 5% weight loss, and activation energy of thermal decomposition of PLLA/PBSA/TFC were far superior to those of PLLA/PBSA/C25A as well as to those of PLLA/PBSA, indicating that the composites with exfoliated silicate layers were more thermally stable than those with intercalated silicate layers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 478–487, 2005     

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     

Cationic ring‐opening polymerization of novel 1,3‐dehydroadamantanes with various alkyl substituents: Synthesis of thermally stable poly(1,3‐adamantane)s

Cationic ring‐opening polymerizations of 5‐alkyl‐ or 5,7‐dialkyl‐1,3‐dehydroadamantanes, such as 5‐hexyl‐ ( 4 ), 5‐octyl‐ ( 5 ), 5‐butyl‐7‐isobutyl‐ ( 6 ), 5‐ethyl‐7‐hexyl‐ ( 7 ), and 5‐butyl‐7‐hexyl‐1,3‐dehydroadamantane ( 8 ), were carried out with super Brønsted acids, such as trifluoromethanesulfonic acid or trifluoromethanesulfonimide in CH₂Cl₂ or n‐heptane. The ring‐opening polymerizations of inverted carbon–carbon bonds in 4–8 proceeded to afford corresponding poly(1,3‐adamantane)s in good to quantitative yields. Poly( 4–8 )s possessing alkyl substituents were soluble in 1,2‐dichlorobenzene, although a nonsubstituted poly(1,3‐adamantane) was not soluble in any organic solvent. In particular, poly( 8 ) exhibited the highest molecular weight at around 7500 g mol^?1 and showed excellent solubility in common organic solvents, such as THF, CHCl₃, benzene, and hexane. The resulting poly( 4–8 )s containing adamantane‐1,3‐diyl linkages showed good thermal stability, and 10% weight loss temperatures (T₁₀) were observed over 400 °C. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4111–4124     

Crosslinked polynorbornene particles synthesis by ring‐opening metathesis polymerization in dispersion

This article proposes the first report on the synthesis of nanometric crosslinked polynorbornene particles by ring‐opening metathesis polymerization in dispersion using ruthenium‐based complex (PCy₃)₂Cl₂Ru?CHPh as initiator. Stable but raspberry‐shaped particles were obtained. In this study, a particular attention was paid to the influence of the crosslinker nature and addition mode on reaction kinetics and morphology of the latex particles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Solid‐phase thermal polymerization of macrocyclic ethylene terephthalate dimer using various transesterification catalysts

Thermal ring‐opening polymerization of a uniform macrocyclic ethylene terephthalate dimer with and without catalyst was investigated for the first time. Although polymerization progressed without a catalyst, the reaction was extremely slow and all the products were colored. Various transesterification catalysts were tested for their activity toward this ring‐opening polymerization. Among the various catalysts, 1,3‐dichloro‐1,1,3,3‐tetrabutyldistannoxane exhibited the highest catalytic activity, and a colorless polymer with a weight‐average molecular weight of 36,100 was obtained in 100% yield by heating for 3 min at 200 °C. It is noteworthy that our method does not need a vacuum because no side products are formed during the process. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3360–3368, 2000