Ring-opening Polymerization Of Epoxides Research Articles

Sequential DMC/FAB-Catalyzed Alkoxylation toward High Primary Hydroxyl, High Molecular Weight Polyether Polyols

A catalytic alkoxylation process to make higher molecular weight poly(propylene oxide) and poly(propylene oxide-co-butylene oxide) polyols containing greater than 65% of primary hydroxyl end groups is described. The one-pot method employs the double metal cyanide catalyst and tris(pentafluorophenyl)borane catalyst (FAB) in a sequential manner and exploits the high primary hydroxyl regioselectivity of FAB over a broad range of temperatures. The process was carried out in two sequential steps: (a) DMC-catalyzed epoxide ring-opening polymerization at a temperature of >130 °C and (b) FAB-catalyzed regioselective capping at a temperature between 60 and 110 °C. The approach thus combines the relative advantages of both the DMC and FAB catalysts: high activity and high primary hydroxyl regioselectivity, respectively. It is also demonstrated that sufficiently low levels of FAB catalyst (e.g., 150 ppm) are sufficient, thus obviating the need for catalyst removal from the final product.

Estimation of the catalytic centre in double metal cyanide catalysts by XAS

Double metal cyanide (DMC) catalysts are commonly applied at industrial ring opening polymerization of epoxides. Nevertheless, the knowledge on the molecular nature of their high activity and selectivity is limited. XAS studies were performed to look for the possible catalytic centre in this family of catalysts. DMC catalysts were synthesized from ZnCl2 and potassium hexacyanocobaltate(III) solution, in the presence of the different organic ligands and show significant fraction of the non-crystalline structure. Two ligands were analysed (tert-butanol (tBuOH) or glyme (CH3OCH2CH2OCH3)). EXAFS analysis established that only Zn atoms are the active metallic centers in DMC regardless the used ligand. The coordination around Zn was changed from octahedral in reference non catalytic material to tetrahedral in catalysts, and Cl atoms were detected near some of Zn atoms.

Pendant cyclic carbonate‐polymer/Na‐smectite nanocomposites via in situ intercalative polymerization and solution intercalation

Nanocomposites of sodium smectite with polyether- and polystyrene-containing pendant cyclic carbonates offer a novel approach to improving hydraulic barrier properties of Na-smectite liners to saline leachates. The cyclic carbonate polyethers were prepared by cationic ring opening polymerization of a cyclic carbonate-containing epoxide, whilst polystyrene polymers having pendant cyclic carbonate groups were obtained from radical photopolymerization of styrene. Na-smectite nanocomposites of these polymers were formed via clay in situ polymerization and solution intercalation methods. X-ray diffraction (XRD) and FT-IR analysis confirmed that the polyether can be intercalated within the layers of smectite via in situ as well as solution intercalation of the pre-formed polymer. The cyclic carbonate polyether nanocomposite was more resistant to leaching in 3M aqueous sodium chloride than its respective cyclic carbonate. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2421–2429

On thermal behaviour of DMC catalysts for ring opening polymerization of epoxides

The thermoanalytical studies of two types of the double metal cyanide catalysts were carried out.The identity of the catalysts was characterized by an elemental analysis and FTIR. The thermoanalytical examinations performed with the use of TG-DSC, EGA-FTIR, EGA-MS shed new light on views of the bonding of the ligands in the DMC. The chemical justification of the processes responsible for the TG/DSC steps was proposed. Several organic ligand complexing states were found in both types of catalysts. The ligand-DMC bondings were decomposing stepwise in relatively low temperature ranges, which could suggest their negligible role at catalytic reaction being performed usually at higher temperatures.The stoichiometric quantitative correlation between the values of TG steps responsible for the ligands evolution, and the concentration of total carbon, nitrogen and cobalt was found.The relationship was used as a base for the quantitative method of characterization of the DMC catalysts.

ゴムの工業的合成法

Epichlorohydrin rubber is synthesized by a ring opening polymerization of epoxides. Epichlorohydrin, ethylene oxide and allyl glycidyl ether are used as epoxides. Industrial production was history of development of a polymerization catalyst. Epichlorohydrin rubber is utilized for automotives and industrial rubber using its performance. On the other hand, new applications continue to be developed with a polymer of epoxides (except epichlorohydrin).

Redox-triggered crosslinking of a degradable polymer

A unique redox-triggered crosslinking reaction is disclosed that capitalizes on the orthogonal reactivity of an iron-based catalyst for the ring opening polymerization of cyclic diesters and epoxides.

Polymers with complicated architectures constructed from the versatile, functional monomer 1-ethoxyethyl glycidyl ether

Because glycidyl (Gly) contains an epoxy and an active hydroxyl group, the Gly unit is difficult to introduce into certain poly-meric chains in a controlled manner and usually yields hyperbranched polyglycidyl. Alternatively, the monomer 1-ethoxy-ethyl glycidyl ether (EEGE), derived from Gly and ethyl vinyl ether, has shown potential for application in polymer chemistry, and homopolymerization of this monomer directly produces linear poly(1-ethoxyethyl glycidyl ether) and further yields linear polyglycidyl. In this review, the initiation system of the EEGE monomer is first discussed in terms of chain transfer to monomers in ring-opening polymerization of epoxides with substituent groups. Then, random copolymerization of EEGE with other epoxides is considered. In addition, because the EEGE units on polymers can be transferred to Gly units and further used to construct copolymers with complicated architectures, the applications of EEGE monomers to block, graft, and hyperbranched copolymers are reviewed. Finally, the synthesis of main chain and terminal functional polyethers by transforming the hydroxyl groups at the polymer end or on the main chain into certain functional groups are also discussed. Chemistry based on EEGE has been proved to be an efficient, versatile route to constructing copolymers containing Gly units and ultimately yielding the target properties and applications.

Synthesis and characterization of group 4 metal alkoxide complexes containing imine based bis-bidentate ligands: effective catalysts for the ring opening polymerization of lactides, epoxides and polymerization of ethylene.

A series of Ti(iv), Zr(iv) and Hf(iv) complexes containing imine based bis-bidentate ligands were synthesized and characterized by various spectroscopic techniques, elemental analysis and X-ray crystallography. The ligands m-xysal-((t)Bu)4 (L(1)((t)Bu)4), m-xysal-(Me)2((t)Bu)2 (L(2)Me2((t)Bu)2) and m-xysal-(Cl)4 (L(3)Cl4) were reacted with Ti(O(i)Pr)4, Zr(O(i)Pr)4·(i)PrOH and Hf(O(t)Bu)4 in a 1 : 1 stoichiometric ratio to form complexes (L2M2(OR)4, where L = m-xysal-((t)Bu)4, m-xysal-(Me)2((t)Bu)2 and m-xysal-(Cl)4, M = Ti and R = (i)Pr, (L2M2(OR)4, where L = m-xysal-((t)Bu)4, m-xysal-(Me)2((t)Bu)2 and m-xysal-(Cl)4, M = Zr and R = (i)Pr and (L3M3(OR)6, where L = m-xysal-((t)Bu)4, m-xysal-(Me)2((t)Bu)2 and m-xysal-(Cl)4, M = Hf and R = (t)Bu respectively. Complex was crystallized from a 1 : 1 : 1 mixture of chloroform, ethanol and toluene to yield an ethoxy substituted complex (L2M2(OR)4, L = m-xysal-(Me)2((t)Bu)2, M = Zr and R = Et. The X-ray structures of , and illustrate that and are binuclear helical complexes, whereas is trinuclear. These complexes were found to be active for the ring opening polymerization (ROP) of lactides (rac-LA, l-LA) and epoxides. All the complexes produced atactic poly(lactic acid) (PLA) with good number average molecular weight (Mn) and narrow molecular weight distributions (MWDs). The magnetic isotropic shielding constants were calculated using the GIAO/B3LYP/LANL2DZ approach and correlated with the experimental values. The HOMO-LUMO energy band gaps and Mulliken charges were calculated using the DFT method to explain the reactivity of these complexes according to the relationship between chemical hardness and reactivity established by Pearson. In addition, complexes , activated by methylaluminoxane (MAO), were used and found to be moderately active for ethylene polymerization.

Ring opening polymerization of epoxides with urea‐derivatives of 4‐aminopyridine as thermally latent anionic initiator

ABSTRACTIn this study, a series of urea‐derivatives of 4‐aminopyridine (4AP) were evaluated as thermally latent initiators for the anionic ring‐opening polymerization of diglycidyl ether of bisphenol A (DGEBA). The urea‐derivatives were synthesized by the reactions of 4AP with the corresponding iso(thio)cyanates (phenyl isocyanate, tert‐butyl isocyanate, methylene diphenyl diisocyanate, and phenyl isothiocyanate). The ability of the urea‐derivatives as latent initiators was investigated with differential scanning calorimetry (DSC): Upon heating formulations comprised of DGEBA and the urea‐derivatives in a heating rate at 10 °C/min, the resulting DSC profiles indicated exothermic peaks to confirm that DGEBA underwent the polymerization efficiently. The corresponding DSC‐peak top temperatures (Tpeak top) was higher than that observed for the formulation comprised of DGEBA and pristine 4AP, to clarify that the urea are useful initiators with thermal latency. A possible mechanism for the initiation step involves the thermal dissociation of the urea into 4AP and the corresponding isocyanates. 4AP thus generated readily initiated the ring‐opening polymerization of epoxide. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2518–2522

The 1,3-bis(dicyanomethylidene)indane skeleton as a (photo) initiator in thermal ring opening polymerization at RT and radical or cationic photopolymerization

1,3-Bis(dicyanomethylidene)indane is presented as a new initiator for ring opening polymerization of epoxides at RT. This compound behaves as a strong acid (AH) with an associated basic form (A−) that does not inhibit the propagation of the cationic polymerization. Remarkably, A− is characterized by a strong visible light absorption and can also photosensitize iodonium salt decomposition. A new iodonium salt based on A− as a counter-anion is proposed. This latter compound exhibits unusual properties: (i) excellent absorption in the 300–700 nm wavelength range and (ii) a free radical initiating ability for λ > 300 nm. The chemical mechanisms are investigated by ESR, fluorescence and steady state photolysis experiments.

Polyethers with phosphate pendant groups by monomer activated anionic ring opening polymerization: Syntheses, characterization and their lithium-ion conductivities

This paper describes the preparations and lithium-ion conductivities of various solid polymer electrolytes for potential use in high-energy density lithium-ion batteries. The ring opening polymerization of epoxides (M1–M6), catalyzed by Zn(II), Cu(II) and Cd(II) complexes in the presence of tetrabutylammonium bromide (TBAB), yielded polyethers (P1–P6) in which phosphates were attached as pendant groups. A reaction condition where Zn(II) catalyst used slightly excess to TBAB increased the polymerization rate remarkably and yielded the polyethers with higher molar masses in a short time. These polymerizations proceeded following a “monomer activated anionic ring opening polymerization” mechanism. These living like polymerizations also progressed according to “formation of polymer chain per initiator” model. The solid-state lithium-ion conductivities of these polymers were examined using lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The conductivity of one of the solid polymer electrolytes with 40 wt% of LiTFSI was 5.2 × 10−5 S cm−1 at room temperature and 2.9 × 10−4 S cm−1 at 80 °C.

Influences of pretreatment and hard baking on the mechanical reliability of SU-8 microstructures

In this paper, the influences of pretreatment and hard baking on the mechanical characteristics of SU-8 microstructures are described. Four types of samples with different combinations of O2 plasma ashing, primer coating and hard baking were prepared for shear strength tests and uniaxial tensile tests. Specially developed shear test equipment was used to experimentally measure the shear adhesion strength of SU-8 micro posts on a glass substrate. The adhesiveness was strengthened by hard baking at 200 °C for 60 min, whereas other pretreatment processes hardly affected the strength. The pretreatment and hard baking effects on the adhesive strength were compared with those on the fracture strength measured by uniaxial tensile testing. There were no influences of O2 plasma ashing on both the strengths, and primer coating affected only tensile strength. The primer coating effect as well as the hard baking effect on stress relaxation phenomena in uniaxial tension was observed as well. Fourier transform infrared spectroscopy demonstrated that surface degradation and epoxide-ring opening polymerization would have given rise to the primer coating effect and the hard baking effect on the mechanical characteristics, respectively.

Photoinitiating systems of polymerization and in situ incorporation of metal nanoparticles into polymer matrices upon exposure to visible light: push–pull malonate and malononitrile based dyes

Novel push–pull dyes containing a (substituted) hydrocarbon moiety and a malonate (or a malononitrile) moiety are proposed as photoinitiators for the ring opening polymerization of epoxides as well as the synthesis of interpenetrated polymer networks (IPNs) upon exposure to visible light (laser diode, halogen lamp, etc.). Excellent polymerization profiles are obtained. The role of the acceptor and donor moieties in these dyes towards their light absorption properties, the associated photochemical processes and their photoinitiating ability is investigated. A very efficient dye has been selected for the reduction of Ag+ and the in situ formation of Ag(0) nanoparticles in the synthesized IPNs.

Naphthalimide based methacrylated photoinitiators in radical and cationic photopolymerization under visible light

The abilities of two naphthalimide derivatives with a methacryloyl group to initiate, when incorporated in multi-component systems, a ring-opening polymerization of epoxides and a radical polymerization of acrylates under different irradiation sources (e.g. very soft halogen lamp irradiation, laser diode at 457 nm, laser diode at 405 nm and blue LED bulb at 462 nm) have been investigated. One of them is particularly efficient for the cationic and radical photopolymerization of an epoxide/acrylate blend in a one-step hybrid cure and leads to the formation of an interpenetrated polymer network IPN (30 s for getting tack free coatings). The migration stability of one of these naphthalimide derivatives is found to be excellent in the cured polyacrylates and IPNs. The photochemical mechanisms are studied by steady state photolysis, fluorescence, cyclic voltammetry, electron spin resonance spin trapping and laser flash photolysis techniques.

有機分子触媒を用いた環状エステル，環状カーボネートおよび環状エーテルの開環重合

有機分子触媒を用いた環状エステル，環状カーボネートおよび環状エーテルの開環重合

Fine Control of Polyester Properties via Epoxide ROP Using Monomers Carrying Diverse Functional Groups

Synthetic biodegradable polymers are important biomaterials. However, most of them are biologically inert. Free functional groups can allow easy biofunctionalization. Efficient introduction of functional groups to biodegradable polymers is still a challenge. Here, a practical strategy is presented to synthesize various functional polyesters with free hydroxyl groups polymerized via epoxide ring-opening polymerization between dicarboxylic acids and diglycidyl dicarboxylates without protection and deprotection. The polymers exhibit a wide range of physical, thermal, and mechanical properties, and good cytocompatibilities. This synthetic platform is expected to lead to functional polymers useful for a wide variety of biomedical applications.

Involvement of Supramolecular Complexes in the Capture and Release of Protonic Acids During the Cationic Ring-Opening Polymerization of Epoxides

The kinetics of the cationic ring-opening polymerizations of epoxide monomers were controlled through the use of supramolecular proton complexes. α,ω-Diglycidyl oligoethylene oxides bearing multiple ethyleneoxy spacer groups form metastable supramolecular proton complexes with strong Bronsted acids generated either by the photolysis of onium salts or by their redox reactions with reducing agents. Trapping of the Bronsted acids by in situ complex formation results in a delay of the onset of cationic ring-opening. However, once polymerization begins, the epoxide groups of the monomer are very rapidly consumed resulting in characteristically highly exothermic autoaccelerated polymerization reactions. Crown ethers can also form supramolecular complexes with hydronium ions derived from the reaction of protonic acids with water and these complexes can be used to modify the kinetic behavior of the cationic ring-opening thermal and photopolymerizations of a variety of epoxide monomers. The ring size of a crown et...

Tuning double metal cyanide catalysts with complexing agents for the selective production of cyclic carbonates over polycarbonates

A double metal cyanide (DMC) complex based on (Zn3[Co(CN)6]2), an effective catalyst for the ring opening polymerization of epoxides and the copolymerization of carbon dioxide with epoxides, was successfully utilized for the solvent-free cycloaddition of CO2 to styrene oxide (SO) by the introduction of cetyltrimethylammonium bromide (CTAB) as a complexing agent (CA). Several DMC catalysts were prepared by introducing co-complexing agents (co-CAs) along with the CA. From the XRD data, it was clear that all the catalysts were amorphous with no peak corresponding to the precursor ZnCl2. XPS analysis was performed to explain the successful introduction of the CA to the DMC catalyst, in which the binding energy of the zinc atom shifted from precursor ZnCl2 to DMC. Elemental analysis and FT-IR also confirmed the incorporation of the CA with Zn3[Co(CN)6]2. The DMC complex was proven to be an effective catalyst for the solvent-free synthesis of styrene carbonate by the cycloaddition of styrene oxide and CO2. This paper reports the tunability of the metal cyanide catalysts with CA for the selective preparation of cyclic carbonates over polycarbonates. 1H NMR and FT-IR confirmed product formation. The effects of reaction parameters like catalyst amount, temperature, CO2 pressure, and reaction time were also investigated.

A biocompatible, metal-free catalyst and its application in microwave-assisted synthesis of functional polyesters

Aliphatic polyesters are one of the most important classes of biodegradable materials. Convergence of functionality and biodegradability represents a major trend in modern materials, especially for biomedical applications and as environmentally friendly alternatives to non-degradable petrochemicals. However, the synthesis of functional polyesters is still a formidable challenge. Most current methods are inefficient and require complex chemical processes. We report a microwave-assisted, acid-initiated epoxide ring opening polymerization. With this one-step synthetic strategy, functional polyesters are produced within half an hour without generation of any byproduct. Thus, our approach represents a significant improvement over current methods by increasing efficiency, minimizing chemical processes, and reducing the usage of hazardous chemicals and waste. The newly designed catalyst, bis(tetrabutylammonium)sebacate, is a metal-free catalyst readily prepared under mild conditions at a large scale. The catalyst is stable and easily stored for more than 7 years under standard storage conditions. Additionally, the catalyst shows good cytocompatibility when tested using primary rat osteoblasts. We expect this technology will be very useful to produce new biodegradable materials.

Functionalization of multi-walled carbon nanotubes by epoxide ring-opening polymerization

In this study, covalent functionalization of carbon nanotubes (CNTs) was accomplished by surface-initiated epoxide ring-opening polymerization. FT-IR spectra showed that polyether and epoxide group covalently attached to the sidewalls of CNTs. TGA results indicated that the polyether was successfully grown from the CNT surface, with the final products having a polymer weight percentage of ca. 14–74 wt%. The O/C ratio of CNTs increased significantly from 5.1% to 29.8% after surface functionalization of CNTs. SEM and TEM images of functionalized CNTs exhibited that the tubes were enwrapped by polymer chains with thickness of several nanometers, forming core–shell structures with CNTs at the center.