Ring-opening Polymerization Of Epoxides Research Articles

Controlled Ring-Opening Polymerization of Epoxides Catalyzed by Metal-Free Phosphazenium Salts (P5+): Using Carboxylic Acid as an Initiator to Prepare Esterified Polyethers

Controlled Ring-Opening Polymerization of Epoxides Catalyzed by Metal-Free Phosphazenium Salts (P₅⁺): Using Carboxylic Acid as an Initiator to Prepare Esterified Polyethers

Polyether/Polythioether Synthesis via Ring-Opening Polymerization of Epoxides and Episulfides Catalyzed by Alkali Metal Carboxylates

Polyether/Polythioether Synthesis via Ring-Opening Polymerization of Epoxides and Episulfides Catalyzed by Alkali Metal Carboxylates

Rational Optimization of Bifunctional Organoboron Catalysts for Versatile Polyethers via Ring-Opening Polymerization of Epoxides

Quaternary ammonium and phosphonium borane bifunctional catalysts have shown high catalytic performance in ring-opening polymerization (ROP) of epoxides to produce polyether. Herein, we systematically investigate a series of well-defined organoboron catalysts by varying the electronic and steric properties of the Lewis acidic boron (B) centers, manipulating the steric hindrance on the ammonium cation (N+), adjusting the distance between B and N+, and regulating the nucleic B number of the catalysts. The investigation on the dinuclear catalysts indicated that the reactivity of a given catalyst could be speculated by its B–N–B angle and the B···B distance. We found that the increase of Lewis acidity and the number of B centers of the organoboron catalysts are useful for a high catalytic activity for ROP of epoxides. The Lewis acidity of the B centers was determined using the acceptor numbers, showing an order of borinane (23.4) > BBN (21.7) > BCy2 (18.8) > Bpin (15.5). Moreover, we demonstrated the production of various telechelic polyols in the presence of different chain transfer agents using the organoboron catalysts. The produced telechelic samples have a well-defined terminal functionality with controllable molecular weight. Lastly, these organoboron catalysts were utilized to produce block copolymers, allyl-terminated macromonomers, and random copolymers.

Exploration of the Synergistic Effect in a One-Component Lewis Pair System: Serving as a Dual Initiator and Catalyst in the Ring-Opening Polymerization of Epoxides

Exploration of the Synergistic Effect in a One-Component Lewis Pair System: Serving as a Dual Initiator and Catalyst in the Ring-Opening Polymerization of Epoxides

Controlling Architecture and Mechanical Properties of Polyether Networks with Organoaluminum Catalysts

Soft materials can sustain large, elastic, and reversible deformations, finding widespread use as elastomers and hydrogels. These materials constitute 3-D polymer networks and are typically synthesized by cross-linking polymer chains or copolymerizing monomer and cross-linker. Seminal investigations have enabled control over the network architecture by cross-linking chains of poly(dimethylsiloxane), poly(1,4-butadiene), or tetra-poly(ethylene glycol); however, as soft materials become attractive for robotics, electronics, and prosthetics, codesigning the network architecture, mechanical, and functional properties has become pressing. We investigate the relationship among reaction pathway, network architecture, and mechanical properties in poly(ethyl glycidyl ether) networks synthesized by epoxide ring-opening polymerization with two organoaluminum catalysts. The key result is that uncontrolled polymerizations yield loosely cross-linked, entangled, soft, and extensible networks, whereas more controlled polymerizations, instead, lead to highly cross-linked, stiff, and brittle networks. Such catalytic control over network architecture and mechanical properties could enable design of novel soft, tough, and functional materials.

Thermal and Electrochemical Properties of Solid Polymer Electrolytes Prepared via Lithium Salt-Catalyzed Epoxide Ring Opening Polymerization

Solid polymer electrolytes have been widely proposed for use in all solid-state lithium batteries. Advantages of polymer electrolytes over liquid and ceramic electrolytes include their flexibility, tunability and easy processability. An additional benefit of using some types of polymers for electrolytes is that they can be processed without the use of solvents. An example of polymers that are compatible with solvent-free processing is epoxide-containing precursors that can form films via the lithium salt-catalyzed epoxide ring opening polymerization reaction. Many polymers with epoxide functional groups are liquid under ambient conditions and can be used to directly dissolve lithium salts, allowing the reaction to be performed in a single reaction vessel under mild conditions. The existence of a variety of epoxide-containing polymers opens the possibility for significant customization of the resultant films. This review discusses several varieties of epoxide-based polymer electrolytes (polyethylene, silicone-based, amine and plasticizer-containing) and to compare them based on their thermal and electrochemical properties.

Synthesis, characterization, and curing of propylene oxide and glycidyl nitrate random copolymer (GN-ran-PO) and investigation of its compatibility with different energetic plasticizers

In this research, arandom copolymer of propylene oxide and glycidyl nitrate (poly [GN-ran-PO]) (Mn = 1152 g.mol−1) was synthesized via ring-opening polymerization of epoxides in the presence of boron trifluoride etherate (BF3.OEt2) as the catalyst. This copolymer has a potential use as a binder in the propellant industries. The obtained product has characterized by 1H and 13C NMR spectroscopy, FTIR, and gel permeation chromatography (GPC). The thermal behavior of the random copolymer was determined by differential scanning calorimetry (DSC). Energetic polyurethane was synthesized by curing of the random copolymer with different curing agents such as toluene-2,4-diisocyanate(TDI), isophorone diisocyanate(IPDI), desmodurN100, (IPDI/N100) and different NCO/OH ratios. To evaluate the plasticizing effect of the different plasticizers on the thermo-mechanical properties of the polyurethane, the compatibility of the copolymer with three energetic plasticizersincludingn‐butyl nitroxyethyl nitramine (BuNENA), trimethylol ethane trinitrate (TMETN), and 1,2,4-butanetriol trinitrate (BTTN) has studied using the solubility parameter, rheological and thermal analysis. The solubility parameter differences indicate that the BuNENA has better miscibility with this copolymer than others. This plasticizer reduced the glass transition temperature of its composition with copolymer from -47 °C to -58 °C. Moreover, the rheological analysis also confirms that BuNENA is more compatible with the copolymer. The mechanical properties effect of the BuNENA plasticizer on the polyurethane network has investigated using dynamic mechanical analysis (DMA) as well as the tensile test. The IPDI/N100 curing agents-polyurethane mixture, demonstrate appropriate mechanical properties (0.6 MPa stress and 109% elongation) that make it a suitable binder system comparison with pure PGN (unstable and de-cured). Also, the mechanical properties of the prepared polyurethane containing 20 wt.% BuNENA showed 0.42 MPa stress and 124% elongation.

Theoretical insight into the opposite redox activity of iron complexes toward the ring opening polymerization of lactide and epoxide

The origin of opposite reactivity in the ring-opening polymerization of lactide (LA) and cyclohexene oxide (CHO) catalyzed by redox-switchable bis(imino)pyridine iron complexes has been computationally elucidated.

A switchable dimeric yttrium complex and its three catalytic states in ring opening polymerization

A dimeric yttrium phenoxide complex can be oxidized in a stepwise fashion to access three oxidation states. The three states show different activity in the ring opening polymerization of cyclic esters and epoxides.

In English

Fumed silica (FS) is widely used in numerous fields of application, the plastics industry being one of the most significance, where FS has proved to be successful as an efficient thickening, thixotropic, and anti-settling agent, as well as reinforcing filler. Chemical modification of silica surface enlarges its functional capabilities. In particular, silica with grafted silicon hydride groups was found to be active in the processes of hydrosilylation of alkene and alkyne bonds in monomers during their polymerization, resulting in the formation of reinforced polymeric composites. Recently, specific epoxy resins have gained significance, and FS was found to be useful, particularly as rheological additive. The aim of this study was to evaluate the efficiency of hydride-silylated FS (HFS) as a potentially active reinforcing component for epoxy-based polymers. The activation energy for hydrosilylation of olefins is higher than that for ring-opening polymerization of epoxides, therefore, one may expect the latter process with participation of ≡SiH groups to proceed more readily. HFS was obtained via FS treatment with triethoxysilane. The presence of grafted silicon hydride groups was confirmed by means of IR spectroscopy, and their concentration measured by titrimetric and spectrophotometric analysis was found to be about 0.4 mmol/g. FS-epoxy and HFS-epoxy composites were prepared by the corresponding filler introduction (2 wt. % loading) into the mixture of epoxy monomer and amine hardener. The resulted materials after curing were subject to compression, bending, and adhesion tests. Compression tests revealed that filling with FS and HFS reduced the compressive strength by 10%, however, HFS-epoxy composite was found to possess an increased by 20 % Young’s modulus for compression as compared to that for the unfilled epoxy polymer. Upon this, 2 wt. % loading with silicas keeps the ductility of the polymer. Also, silica-containing epoxy polymers showed an improved bending strength and bending modulus, the former being two times higher for HFS-epoxy composite than that for the unfilled polymer. The adhesion to steel was found to increase by more than 2 times upon filling with silicas, HFS-epoxy composite being also superior as compared to the FS-epoxy one. Thus, preliminary results indicate that fumed silica with grafted silicon hydride groups shows promise as active reinforcing filler for epoxy polymers.

Co-Oligomers of Renewable and “Inert” 2-MeTHF and Propylene Oxide for Use in Bio-Based Adhesives

Commercial polyether polyols are usually obtained by the ring-opening polymerization of epoxides or tetrahydrofuran. 2-Methyl-tetrahydrofuran (2-MeTHF) could be an alternative bio-based building block for the synthesis of these polyols. Although 2-MeTHF cannot be polymerized, we did achieve the copolymerization of 2-MeTHF with propylene oxide (PO) using Lewis and Bronsted acids as catalysts and water or diols as initiators. The resulting polyether polyols have a molecular weight range, which allows their use as components for adhesives. The molar content of 2-MeTHF in the oligomers can be up to 48%. A 1:1 copolymer of 2-MeTHF and PO is produced when stoichiometric amounts of BF3·OEt2 are used. Here, the monomeric units in the chains alternate, but also cyclic or other nondiol products are formed that are detrimental to its further use in adhesives. Linear dihydroxyl-terminated polyether chains were formed when the heteropolyacid H3PW12O40·24H2O was used as a catalyst and a diol as an initiator. The formation of cyclic products can be drastically reduced when the accumulation of propylene oxide during the reaction is avoided. 1H NMR experiments indicate that the step of 2-MeTHF incorporation is the alkylation of 2-MeTHF by protonated PO. It was shown that the 2-MeTHF/PO copolymer had increased tensile strength compared to polypropylene glycol in a two-component adhesive formulation.

Ring-opening polymerization of epoxides and ring-opening copolymerization of CO2 with epoxides by a zinc amino-bis(phenolate) catalyst

A one-pot synthesis of poly(ether-co-carbonates) catalyzed by an amino-bis(phenolate) zinc catalyst [L]Zn2Et2(THF) 1 (where [H2L] = n-propylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol) has been developed. Ring-opening polymerization (ROP) of cyclohexene oxide (CHO) can be performed by 1 with and without addition of BnOH or PPNCl as co-catalysts. The ROP of CHO can be inhibited by CO2 pressurization, which leads to the formation of polycarbonate blocks, or presence of other epoxides, which leads to the formation of poly(ether-co-carbonate) containing carbonate linkages and ether linkages. Polycarbonate formation was observed at 1 bar CO2 giving 23% carbonate linkages at this pressure. At 20 bar CO2, 92% carbonate formation was achieved in the presence of limonene oxide (LO). Poly(ether-co-carbonates) from mixtures of epoxides could be synthesized by changes in reaction temperatures and pressures.

Easy access to oxygenated block polymers via switchable catalysis

Oxygenated block polyols are versatile, potentially bio-based and/or degradable materials widely applied in the manufacture of coatings, resins, polyurethanes and other products. Typical preparations involve multistep syntheses and/or macroinitiator approaches. Here, a straightforward and well-controlled one-pot synthesis of ABA triblocks, namely poly(ether-b-ester-b-ether), and ABCBA pentablocks, of the form poly(ester-b-ether-b-ester’-b-ether-b-ester), using a commercial chromium catalyst system is described. The polymerization catalysis exploits mechanistic switches between anhydride/epoxide ring-opening copolymerization, epoxide ring-opening polymerization and lactone ring-opening polymerization without requiring any external stimuli. Testing a range of anhydrides, epoxides and chain-transfer agents reveals some of the requirements and guidelines for successful catalysis. Following these rules of switch catalysis with multiple monomer additions allows the preparation of multiblock polymers of the form (ABA)n up to 15 blocks. Overall, this switchable catalysis delivers polyols in a straightforward and highly controlled manner. As proof of potential for the materials, methods to post-functionalize and/or couple the polyols to make higher polymers are demonstrated.

Direct insight into the kinetics of the high-pressure step-growth polymerization of DGEBA/aniline model system

In this paper, the high-pressure calorimetry was used to monitor the heat of the polymerization of bisphenol-A diglycidyl ether (DGEBA) mixed with a stoichiometric amount of aniline over a wide range of pressure (p = 0.1–350 MPa at T = 298.15 K). To the best of our knowledge, this is the first high-pressure calorimetric study of the reaction kinetics of the epoxy resin curing processes. The collected novel experimental data were analysed with two models: the original Kamal and its modified version taking into account the real monomer conversion, which provides insight into the progress of two subsequent non-catalyzed and catalyzed reactions occurring during the step growth polymerization. It was found that the determined rate constants are sensitive to pressure and model dependent, resulting in different activation volumes, which fall within the range from −16 cm3/mol to −26 cm3/mol. Interestingly, these values are similar to those reported for the epoxide ring-opening polymerization reaction, which changes in the range between −15 cm3/mol to −20 cm3/mol. In addition, the analysis of the high-pressure data revealed that the original Kamal model fails to describe kinetic curves obtained for the polymerization reaction, where the monomer conversion is far below 100%. Interestingly, such effects are considered to be due to the change in the mechanism of the reaction from mass to the diffusion-controlled regime. Here, we explicitly have shown that it has nothing to do with this phenomenon since after considering solely the real monomer conversion in the Kamal model fits, quality has been significantly improved. As a consequence, estimated rate constants are more reliable. Results presented herein clearly indicated that high-pressure experiments provide a new perspective to understand the progress of the classical reactions, as step-growth polymerization that has mainly been studied as a function of the chemical composition and temperature.

A Biocompatible, Biodegradable, and Functionalizable Copolyester and Its Application in Water-Responsive Shape Memory Scaffold

Shape memory polymers are of great interest for biomedical applications. However, most stimuli used to trigger shape memory processes, including heat, light, electricity, magnetism, and pH are inconvenient and maybe harmful to the body. Here, we designed and fabricated a new shape memory porous scaffold using biocompatible and readily available water as the trigger. This scaffold was based on poly(fumaricacid-co-1,7-octadiene diepoxide-co-terephthalic acid) (PFOT) synthesized via epoxide ring-opening polymerization in one step. The PFOT scaffold promoted the adhesion, spreading, proliferation and function of cardiomyoblast H9C2 cells in a manner comparable to that for the poly(lactic-co-glycolic acid) scaffold. It exhibited an excellent water-responsive shape memory effect with a fixity and recovery ratio >97% and a shape-recovery process of several minutes, suitable for surgery. In addition, the PFOT scaffold presented good in vitro biodegradation. More importantly, PFOT contains extensive free hydroxyl ...

Cationic indium complexes for the copolymerization of functionalized epoxides with cyclic ethers and lactide.

We report the first example of discrete cationic indium complexes for the copolymerization of epoxides, cyclic ethers, and lactide. [SalenIn][SbF6] in particular proved to be a highly active catalyst for the homo-polymerization of functionalized epoxides and their copolymerization with other cyclic ethers THF, oxetane and oxepane. This catalyst also proved competent in the polymerization of epichlorohydrin and lactide, forming copolymers with good activity and control. Investigation of the role of counteranions and solvent donors on the kinetics of polymerization of epoxides revealed a subtle effect of solvents on initiation rates.

Crystalline CO2 -Based Aliphatic Polycarbonates with Long Alkyl Chains.

Carbon dioxide (CO2 ) is an easily available, renewable carbon source and can be utilized as a comonomer in the catalytic ring-opening polymerization of epoxides to generate aliphatic polycarbonates. Dodecyl glycidyl ether (DDGE) is copolymerized with CO2 and propylene oxide (PO) to obtain aliphatic poly(dodecyl glycidyl ether carbonate) and poly(propylene carbonate-co-dodecyl glycidyl ether carbonate) copolymers, respectively. The polymerization proceeds at 30°C and high CO2 pressure utilizing the established binary catalytic system (R,R)-Co(salen)Cl/[PPN]Cl. The copolymers with varying DDGE:PO ratios are characterized via NMR, FT-IR spectroscopy, and SEC, exhibiting high molecular weights between 11400 and 37900 g mol-1 with dispersities (Ð=M w /M n ) in the range of 1.37-1.61. Copolymers with T g s of -11°C or T m s from 5 to 15°C and thermal decomposition >200°C depending on the comonomer ratio, are obtained as determined by differential scanning calorimetry/TGA.

Poly (Terephthaloyl Diglyceride-co-1, 2-cyclohexanediacyl Diglyceride) - A Biodegradable and Biocompatible Functional Polymer for Biomedical Applications

Biodegradable polyesters have been widely used in biomedical engineering. Introduction of functional groups to polyesters will expand their applications. Herein, we developed a functionalizable copolyester with free hydroxyl groups (-OH) - poly (terephthaloyl diglyceride-co-1,2-cyclohexanediacyl diglyceride) (PTeCD). PTeCD was readily synthesized by acid-induced epoxide ring-opening polymerization in one step. Its structure was characterized by NMR and FTIR. PTeCD exhibited a good cytocompatibility and biodegradability. We expect PTeCD will be a useful polymer for biomedical applications.

Investigation of redox switchable titanium and zirconium catalysts for the ring opening polymerization of cyclic esters and epoxides

The synthesis and characterization of (thiolfan*)Zr(OtBu)2 (thiolfan* = 1,1′-di(2,4-di-tert-butyl-6-thiophenoxide)ferrocene) is reported, as well as its activity toward the ring-opening polymerizations of l-lactide and ε-caprolactone.

Four-fold increase in epoxide polymerization rate with change of alkyl-substitution on mono-μ-oxo-dialuminum initiators

We present an improvement in the rate, utility, and mechanistic understanding of mono-μ-oxo-dialuminum initiators for epoxide ring-opening polymerization.