Ring-opening Polymerization Of Cyclic Carbonates Research Articles

Sustainability of Nonisocyanate Polyurethanes (NIPUs)

This work discusses the synthesis and properties of nonisocyanate polyurethanes (NIPUs) as an environmentally friendly alternative to traditional polyurethanes. NIPUs are made without the use of toxic isocyanates, reducing the environmental impact and safety concerns associated with their production. However, their synthesis reactions often require longer time and more energy to be completed. The sustainability of NIPUs is considered from various angles; the main methods for the synthesis of NIPUs, including rearrangement reactions, transurethanization, and ring-opening polymerization of cyclic carbonates with amines, are examined. Another part focuses on renewable sources, such as vegetable oils, terpenes, tannins, lignins, sugars, and others. The synthesis of waterborne and solvent-free NIPUs is also discussed, as it further reduces the environmental impact by minimizing volatile organic compounds (VOCs) and avoiding the use of harmful solvents. The challenges faced by NIPUs, such as lower molecular weight and higher dispersity compared to traditional polyurethanes, which can affect mechanical properties, were also addressed. Improving the performance of NIPUs to make them more competitive compared to conventional polyurethanes remains a key task in future research.

Preparing Well-Defined Polyacrylamide-b-polycarbonate by Integrating Photoiniferter Polymerization and TBD-Catalyzed ROP.

The dual-initiator technique allows the polymerization of different monomers from orthogonal polymerization mechanisms to obtain block copolymers (BCPs). In this study, it is attempted to combine photoiniferter living free radical polymerization and organocatalytic ring-opening polymerization (ROP) to design a hydroxyl-functionalized carbamodithioate, i.e., 4-(hydroxymethyl)benzyl diethylcarbamodithioate (HBDC), which can integrate photoiniferter polymerization of acrylamide monomers and ROP of cyclic carbonates. As a proof of concept, the monomer applicability is further extended to acrylates and lactones. The results confirm that the two polymerization systems are experimentally compatible in a stepwise sequence as well as in a simultaneous one-pot process to synthesize BCPs. It is reasonable to assume that HBDC can allow for simple and efficient one-pot access to well-defined BCPs from a larger range of monomers, which is more advantageous from the operational, economical, and environmental points of view.

Trimethyl Glycine as an Environmentally Benign and Biocompatible Organocatalyst for Ring-Opening Polymerization of Cyclic Carbonate

Trimethyl glycine (TMG), a natural product found in plants as well as in humans, was demonstrated to be an efficient catalyst for the ring-opening polymerization (ROP) of cyclic carbonate, enabling...

Polycondensation as a Versatile Synthetic Route to Aliphatic Polycarbonates for Solid Polymer Electrolytes

Recently, polycarbonates have been proposed as alternative materials to poly(ethylene oxide) as the polymeric matrix for solid polymer electrolytes (SPEs). Aliphatic polycarbonates SPEs have shown excellent ionic conductivity values even at room temperature, good electrochemical stability and high lithium transference number. In most works, the aliphatic carbonates have been synthesized using two main routes, ring-opening polymerization of cyclic carbonates and copolymerization between CO2 and epoxides. Although these synthetic routes are successful, impose wither 2 or 3 carbon aliphatic chain between the carbonate groups. In this paper we propose conventional polycondensation as a route to aliphatic polycarbonates for solid polymer electrolytes. Thus, we synthesized a series of eight different aliphatic polycarbonates by polycondensation of aliphatic diols and dimethyl carbonate. The reactions were carried out using an organocatalyst under melt-condensation conditions at temperatures ranging between 130 and 180°C. A series of eight different aliphatic polycarbonates were obtained having between 4 and 12 methylene groups between the carbonate units in each repeating unit and molecular weights between 8,000 and 43,000gmol−1. All the aliphatic polycarbonates were semicrystalline showing melting temperatures within 45 and 63°C and glass transition temperatures around −40°C. The use of those aliphatic polycarbonates as matrix for solid polymer electrolytes was evaluated. First, adding 30wt% of LiTFSI, the best ionic conductivity measured at ambient temperature 6·10−6Scm−1 was obtained from poly(heptamethylene carbonate). Then, adding different salt weight percent (from 20 to 80wt%), the highest value was obtained for low molecular weight poly(dodecamethylene carbonate) using 80wt% of LiTFSI which showed an excellent ionic conductivity value of 1·10−4Scm−1 at room temperature.

Cationic ring-opening polymerization of cyclic carbonates and lactones by group 4 metallocenes: A theoretical study on mechanism and ring-strain effects

Group 4 metallocene-mediated cationic ring-opening polymerizations of a series of lactones and cyclic carbonates, with different ring sizes ([Formula: see text]–8) have been theoretically studied. Using the “naked cation” approach in combination with density functional theory, the activated chain-end mechanism and the influence of transition metals, solvent and monomer ring size on the polymerizability were explored in detail. The results showed that the cationic metallocene–monomer complex, [catalyst][monomer][Formula: see text], is formed, generating cationic (carbocation ion) species responsible for polymer chain growth. We found that poor polymerizability of five-membered lactone and six-membered ring carbonate depends not only on the nature of the monomer ring size but also the relative stability of the complex, which was found to correlate well with the ring strain. Subsequently, several propagation steps take place through an SN2 reaction which involves ring opening of an active monomer, via alkyl–oxygen bond cleavage. Based on the computed activation energies of all metallocene systems, the first propagation was found to be the rate-determining step of the overall propagation and the hafnocene was found to be most active with the energy barrier of 17.6[Formula: see text]kcal/mol, followed by zirconocene (18.6[Formula: see text]kcal/mol) and titanocene (19.5[Formula: see text]kcal/mol), respectively. The mechanistic study may be applicable to the cationic ROP of lactides and other related monomers.

Direct Copolymerization of CO2 and Diols.

Direct polymerization of CO2 and diols is promising as a simple and environmental-benign method in place of conventional processes using high-cost and/or hazardous reagents such as phosgene, carbon monoxide and epoxides, however, there are no reports on the direct method due to the inertness of CO2 and severe equilibrium limitation of the reaction. Herein, we firstly substantiate the direct copolymerization of CO2 and diols using CeO2 catalyst and 2-cyanopyridine promotor, providing the alternating cooligomers in high diol-based yield (up to 99%) and selectivity (up to >99%). This catalyst system is applicable to various diols including linear C4-C10 α,ω-diols to provide high yields of the corresponding cooligomers, which cannot be obtained by well-known methods such as copolymerization of CO2 and cyclic ethers and ring-opening polymerization of cyclic carbonates. This process provides us a facile synthesis method for versatile polycarbonates from various diols and CO2 owing to simplicity of diols modification.

Homopolymerization and copolymerization kinetics of trimethylene carbonate bearing a methoxyethoxy side group

The polymerization kinetics of 5-[2-{2-(2-methoxyethoxy)ethyoxy}-ethoxymethyl]-5-methyl-trimethylene carbonate (TMCM-MOE3OM) synthesized using the organocatalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were studied and compared to those with the commonly used catalyst/initiator for ring-opening polymerization of cyclic carbonates and esters, stannous 2-ethylhexanoate. Further, the utility of each of these catalysts in the copolymerization of TMCM-MOE3OM with trimethylene carbonate (TMC) and l-lactide (LLA) was examined. Regardless of conditions with either catalyst, homopolymerization of TMCM-MOE3OM yielded oligomers, having number average molecular weight less than 4000 Da. The resultant molecular weight was limited by ring-chain equilibrium as well as through monomer autopolymerization. Interestingly, autopolymerization of TMC was also achieved with DBU as the catalyst. Copolymerization with TMC using stannous 2-ethylhexanoate as the catalyst yielded random copolymers, while diblock copolymers were formed by copolymerization with LLA. With DBU as the catalyst, copolymers with LLA could not be formed, while blocky copolymers were formed with TMC. These findings should be useful in the incorporation of this monomer in the design of polymer biomaterials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 544–552

Structurally dynamic hydrogels derived from 1,2-dithiolanes.

The design and generation of adaptable materials derived from structurally dynamic polymers provides a strategy for generating smart materials that can respond to environmental stimuli or exhibit self-healing behavior. Herein we report an expedient organocatalytic ring-opening polymerization of cyclic carbonates containing pendant dithiolanes (trimethylene carbonate/dithiolane, TMCDT) from poly(ethylene oxide) diols to generate water-soluble triblock (ABA) copolymers containing a central poly(ethylene oxide) block and terminal dithiolane blocks. Hydrogels generated from the triblock copolymers and a cross-linking dithiol exhibited dynamic behavior as a result of the reversible ring opening of the pendant 1,2-dithiolanes. These materials exhibit self-healing behavior, can be injected through a syringe, and rapidly recover their mechanical properties after a severe strain deformation. The dynamic properties of these gels can be modulated with the number of dithiolane units, pH, and temperature.

Photo-responsive reversible micelles based on azobenzene-modified poly(carbonate)s via azide–alkyne click chemistry

We provide a convenient method to construct photo-responsive poly(carbonate)s via ring-opening polymerization of cyclic carbonates followed by azide–alkyne click chemistry.

Recent advances in metallo/organo-catalyzed immortal ring-opening polymerization of cyclic carbonates

The ring-opening polymerization of cyclic carbonate monomers derived from biomass feedstocks constitutes an attractive way to prepare polycarbonates that are potentially useful as high-tech materials or commodity “bioplastics”. This process can be catalyzed by inherently different systems ranging from simple basic organocatalysts, simple Lewis acidic metallic salts such as triflates, or more sophisticated discrete metallo-organic complexes derived from oxophilic metals (zinc, yttrium). In this perspective, the most recent achievements in this chemistry are reviewed. The quite different performances within reach of those catalytic systems, which are assessed in terms of intrinsic reactivity, robustness and regioselectivity towards dissymmetric monomers, are highlighted.

Highly Efficient Aluminum-Catalyzed Ring-Opening Polymerization of Cyclic Carbonates, Lactones, and Lactides, Including a Unique Crystallographic Snapshot of an Intermediate

The synthesis of a new well-defined aluminum-based catalyst (1) for the ring-opening polymerization of cyclic carbonates, lactones, and lactides is described. Compound 1 is supported by a cheap and...

DFT investigations on the ring-opening polymerization of cyclic carbonates catalyzed by zinc-{β-diiminate} complexes

The ring-opening polymerizations of trimethylene (TMC) and tetramethylene (7CC) carbonates using [(BDIiPr)Zn(N(SiMe3)2)] (BDIiPr = 2-((2,6-diisopropylphenyl)amido)-4-((2,6-diisopropylphenyl)-imino)-2-pentene) as catalyst precursor, in the presence of benzyl alcohol (BnOH) as co-initiator, have been investigated by means of density functional theory (DFT) calculations. This computational study highlights that the zinc-amido precursor is by itself a poor catalyst whereas the alkoxide analogue, obtained upon alcoholysis of the Zn–N bond by BnOH, is very active. For both TMC and 7CC, the initiation and the first propagation steps have been computed. In each case, the reaction proceeds via two transition states, involving nucleophilic attack of the alkoxide group followed by the ring-opening of the cyclic carbonates. Thus TMC and 7CC undergo a similar ROP process with accessible energy barriers. The analysis of the reaction mechanisms and energy profiles indicates that the relaxation of the growing polymer chain is an important feature, making the overall reaction exergonic (7CC) or athermic (TMC). This exothermicity difference predicts that 7CC is slightly more easily polymerizable than TMC, which is consistent with what is already known in the case of six- and seven-membered related lactones and previous experimental investigations on TMC and 7CC.

Living ring-opening polymerization of cyclic carbonates mediated by bulky titanium bisphenolates

Dichlorotitanium {2,2′-methylenebis(6-tert-butyl-4-methylphenolate)} (2) brought about living homopolymerization and copolymerization of cyclic carbonates with 6- and 7-membered rings to give the corresponding polycarbonates with narrow molecular weight distribution. 1H and 13C NMR studies of the polycarbonates obtained by 2 showed the presence of terminal hydroxy groups at both polymer ends, although no signals assignable to a chlorobutyl group or bisphenolate group were observed. 1H and 13C NMR spectroscopy of the polymerization system showed that the cyclic carbonate molecule is coordinated to the titanium complex, whereas the structure of the titanium complex was almost unchanged throughout the polymerization. The polymerization is considered to proceed via a nucleophilic attack of hydroxy groups at the polymer ends on the cyclic carbonates activated by 2.

Novel ring-opening polymerization and its application to polymeric materials

Ring-opening polymerization of cyclic carbonates was studied. Volume expansion during polymerization of cyclic carbonates could be explained by the difference between intermolecular interaction of monomers and polymers, which was evaluated by dipole moment. A seven-membered cyclic carbonate polymerized much faster than a six-membered one. Bulky substituents of six-membered cyclic carbonates increased the equilibrium monomer concentration. A novel initiator system, combination of alcohol and trifluoroacetic acid, efficiently polymerized cyclic carbonates.

Acid-Promoted Living Ring-Opening Polymerization of Cyclic Carbonates with B(OR)3

Ring-opening polymerization of cyclic carbonates (1,3-dioxepan-2-one and 5,5-dimethyl-1,3-dioxan-2-one) with triethyl and triisopropyl borates as initiators promoted by hydrogen chloride was carried out. The molecular weights of the obtained polymers could be controlled by the amount of alkylborates, and their polydispersity ratios were small (∼1.15). The polymerization obeyed good first-order kinetics throughout the reaction. After the monomers were completely consumed, the polymerization proceeded again quantitatively when the same amount of monomers were introduced into the polymerization mixtures. 1H and 13C NMR spectroscopic studies suggested that the polymerization proceeded in a living manner via insertion of the monomer to the boron−oxygen bond.

Synthesis and Structure of Optically Active Helical Poly- and Oligocarbonates Consisting of C2-Chiral Biphenyl Unit

Enantiomerically pure (R)-4,4′,6,6′-tetramethyl-2,2′-dihydroxybiphenyl ((R)-6) and the corresponding cyclic carbonate were prepared along with racemic ones ((±)-6 and (±)-7). The X-ray crystallographic analysis of (±)-7 supported the proposed cyclic carbonate structure. Anionic ring-opening polymerization of cyclic carbonate (R)-7 with t-BuOK in THF gave thoroughly insoluble materials. Alternatively, soluble polycarbonate ((R)-5) with low molecular weight was synthesized by polycondensation of (R)-6. The model oligomers of (R)-5 (2 - 8mers) were synthesized (R)-5 exhibited large negative Cotton effect around 210 nm compared with that of its unit model ((R)-9) in the CD spectra CD spectral study and structure simulation of the model oligomers ((R)-11 - 13) suggested that (R)-5 and higher oligomers can hold a stable left-handed helix in solution.

Living ring-opening polymerization of cyclic carbonates by titanium bisphenolate complexes

Living ring-opening polymerization of cyclic carbonates by titanium bisphenolate complexes

Living ring-opening polymerization of cyclic carbonates by titanium bisphenolate complexes

2,2′-Methylenebis(6-tert-butyl-4-methylphenolate) titaniumdichloride (1 a) brought about the living polymerization of 1,3-dioxepan-2-one (7CC) to give polymers with narrow molecular weight distributions. The molecular weight of the obtained polycarbonate could be controlled by changing the initial mole ratio of 7CC and 1 a. The polycarbonate thus formed has hydroxymethylene terminal units at both ends.

Ring-opening polymerization of cyclic carbonates by alcohol-acid catalyst

Ring-opening reactions of 1,3-dioxepan-2-one (1) and 1,3-dioxan-2-one (2) with several alcohols were examined. The reactions proceeded without trifluoroacetic acid (TFA) in low conversions, while they proceeded smoothly with TFA to afford the ring-opened adducts and oligomers. Ring-opening polymerizations of 1 and 2 were also carried out by alcohol–acid catalysts to afford the corresponding polycarbonates (Mn = 2500−6800). The molecular weights increased with increase of the conversions of 1 and 2. The observed polymerization rates of 1 and 2 were determined as 24.4 × 10−6 and 0.8 × 10−6 s−1, respectively. Mechanistic aspects were studied by NMR spectroscopy. The methylene protons α and β to the carbonate moieties shifted to lower fields in 0.06–0.11 ppm in the 1H-NMR spectra by the addition of TFA. Downfield shifts of the carbonyl carbon signals of 1 and 2 were observed in 3.94–4.15 ppm in the 13C-NMR spectra. These results strongly suggest that the cyclic carbonates are activated by TFA. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2463–2471, 1998

Cationic Ring-Opening Polymerization of Cyclic Carbonates with Alkyl Halides To Yield Polycarbonate without the Ether Unit by Suppression of Elimination of Carbon Dioxide

Cationic ring-opening polymerization of cyclic carbonates with alkyl halide as initiator during which no decarboxylation takes place is described in detail, using 5,5-dimethyl-1,3-dioxan-2-one (1), 1,3-dioxan-2-one (2), 5-n-butyl-1,3-dioxan-2-one (5), and 1,3-dioxaspiro[5.5]undecan-2-one (6) as monomers. Cationic polymerizations of 2, 5, and 6 with cationic initiators such as methyl triflate and boron trifluoride etherate were carried out under various conditions. In the polymerizations decarboxylation (elimination of carbon dioxide) during the polymerization occurred to yield the corresponding polycarbonate with ether units (5−10%) in the main chain. 6 only gave a small amount of polymer. Prolonged reaction time and enhanced temperature accelerated the decarboxylation. Reactions of the polycarbonate of 2 with several cationic initiators including methyl iodide were monitored by 1H NMR and gel permeation chromatography. Both a decrease in the polymer molecular weight and an increase in the ratio of ether ...