Ring-opening metathesis polymerization of 9-phenyl-1,5-cyclododecadiene

Synthesis of butadiene-based sequence-controlled copolymers that are composed of commercial monomers such as styrene, butadiene, and ethylene was investigated. New substituted cyclododecadiene derivatives, 9-phenyl-1,5-cyclododecadiene was synthesized by reductive-phenylation method from 1,5-cyclododecadiene-9-one and was polymerized with tungsten-based catalyst systems to obtain a microstructure-controlled terpolymer. A sequence-controlled 2 : 1 : 1 terpolymer of butadiene, styrene and ethylene was successfully synthesized. The glass transition of the terpolymer occurred at ?33.6°C. © 1995 John Wiley & Sons, Inc.     

Detailed study of the ring-opening metathesis polymerization of norbornene bearing a five- or six-membered ring cyclic carbonate along with volume expansion

The ring-opening metathesis polymerization (ROMP) of norbornene derivatives bearing five- or six-membered cyclic carbonate ( 2 or 3 ) was carried out with a typical ruthenium catalyst [bis(tricyclohexylphosphine)benzylidene ruthenium(IV) dichloride], the so-called first-generation Grubbs catalyst, under various reaction conditions, to smoothly obtain the corresponding polyalkenamers ( 5 and 6 ) along with volume expansion. The number-average molecular weights (M_n's), 10% weight loss decomposition temperatures, glass-transition temperatures (T_g's), and volume expansion ratios of the resulting products depended on the polymerization conditions. The degree of volume expansion was mainly affected by M_n, T_g, and the cis/trans configuration of the exocyclic double bonds of the resulting polymers. The volume expansion was confirmed to specifically occur during the polymerization of the monomer bearing cyclic carbonate moieties, and similar ROMPs of monomers without cyclic carbonate, such as norbornene itself, the monomer 5,5-bis(methoxymethyl)bicyclo[2.2.1]hept-2-ene, and the monomer endo-N-methylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylimide, proceeded along with volume shrinkage. Furthermore, an investigation of another type of polymerization, a vinyl-type one, of monomer 2 suggested that the volume expansion specifically took place in the ring-opening type of polymerization. In addition, the Sc(OTf)₃-mediated cationic ring-opening reaction of the cyclic carbonate moiety of polyalkenamer 5 smoothly proceeded along with volume expansion or nearly zero volume shrinkage to yield the corresponding networked polymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 395–405, 2006     

Ring-opening metathesis polymerization of cis-5-norbornene-endo-2,3-dicarboxylic anhydride derivatives using the grubbs third generation catalyst

A series of cis-5-norbornene-endo-2,3-dicarboxylic anhydride(NDCA,M1) derivatives(M2-M4) with different types of nonpolar substituted groups were synthesized and characterized by ~1H/~(13)C-NMR and mass spectrometry(MS). Ringopening metathesis polymerization(ROMP) of these monomers using the Grubbs third generation catalyst(G3) generated high molecular weight polymers with much improved solubility compared with the NDCA's homopolymer. It was found that the solubility of these polymers increased with increased substituent's steric hindrance. The living polymerization of NDCA derivative containing the bulkiest substituent(M4) catalyzed by G3 in tetrahydrofuran was confirmed by the kinetic studies with low polydispersity indices(PDI)( 1.30). By using sequential ROMP, well-defined diblock copolymers containing anhydride groups were synthesized.     

Synthesis of triblock copolymers—(polyA-poly butadiene-polyA)—via metathesis polymerization

A series of triblock copolymers of the type A-B-A were synthesized using tungsten chloride-anchored hydroxyl-terminated polybutadiene (HTPBD) catalyst. Monomers like phenylacetylene (PA), norbornene (NBE), cyclooctadiene (COD), and cyclopentene (CP) were polymerized via metathesis pathway using this catalyst. The efficiency of this anchored catalyst in producing A-B-A triblock copolymers was explored and compared under the same experimental conditions like solvent system and reaction temperature. This anchored catalyst upon reaction with PA produced polyPA-block-polyBD-block-polyPA in high yield and with low polydispersity (pdi) compared to HTPBD. The formation of the triblock copolymers by this method was evinced by NMR, TGA, and GPC data as well as by delinking and inverse addition studies. All the cycloalkenes polymerized via ring-opening metathesis polymerization (ROMP) with the catalyst and yielded triblock copolymers. The mode of synthesis of triblocks could be construed as switching the mechanism of polymerization from radical to olefin metathesis. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2601–2610, 1998     

Polymerizability of norbornene in ring-opening metathesis polymerization initiated by Mo-based complexes

Concerning the study on the relation between structural parameters and reactivity in ring-opening metathesis polymerization of cyclo-olefins, the “living” polymerization of norbornene initiated by Schrock's-type complexes was considered as a reference and studied from the kinetic point of view. First kinetic orders with respect to both monomer and active species allow the values of absolute rate constants of propagation to be determined. The thermodynamic parameters obtained from kinetic experiments performed at different temperatures seem to indicate that monomer coordination and metallacycle formation are rate-determining steps in the process studied. © 1994 John Wiley & Sons, Inc.     

Ring-opening polymerization of six- and seven-membered cyclic pseudoureas

The cationic ring-opening polymerization of six-membered cyclic pseudoureas, 2-(1-pyrrolidinyl)- ( 2a ) and 2-morpholino-5,6-dihydro-4H-1,3-oxazine ( 2b ), was examined, which proceeded in two different ways, depending on the nature of initiator. The polymerization of 2 with methyl p-toluenesulfonate or trifluoromethanesulfonate (MeOTf) produced poly[(N-carbamoylimino)trimethylene], while that with benzyl chloride or bromide or methyl iodide gave a polymer consisting of 1,3-diazin-2-one-1,3-diylalkylene unit (the main component) and (N-carbamoylimino)trimethylene unit. The cationic ring-opening polymerization of seven-membered cyclic pseudourea, 2-(1-pyrrolidinyl)-4,5,6,7-tetrahydro-4H-1,3-oxazepine ( 3 ) was also examined. The polymerization of 3 with MeOTf as initiator gave poly{[N-(1-pyrrolidinycarbonyl)imino]tetra-methylene}. With benzyl chloride, on the other hand, no polymerization of 3 proceeded but, instead, the quantitative isomerization of 3 to 1,1′-carbonyldipyrrolidine took place. The polymerization mechanism of 2 and 3 as well as the isomerization mechanism of 3 were discussed with comparing them to the polymerization mechanism of five-membered pseudoureas. © 1977 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 933–945, 1997     

Ring-opening metathesis polymerization for the preparation of norbornene-based weak cation-exchange monolithic capillary columns

Functionalized monolithic columns were prepared via ring-opening metathesis polymerization (ROMP) within silanized fused silica capillaries with an internal diameter of 200 μm by in situ grafting. This procedure is conducted in two steps, the first of which is the formation of the basic monolithic structure by polymerization of norborn-2-ene (NBE) and 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene (DMN-H6) in a porogenic system (toluene and 2-propanol) using RuCl₂(PCy₃)₂(CHPh) as ROMP initiator. In the second step the still active initiator sites located on the surface of the structure-forming microglobules were used as receptor groups for the attachment (“grafting”) of functional groups onto the monolithic backbone by flushing the monolith with 7-oxanorborn-2-ene-5,6-carboxylic anhydride (ONDCA). Functionalization conditions were first defined that did not damage the backbone of low polymer content (20%) monoliths allowing high-throughput chromatographic separations. Variation of the functionalization conditions was then shown to provide a means of controlling the degree of functionalization and resulting ion-exchange capacity. The maximum level of in situ ONDCA grafting was obtained by a 3 h polymerization in toluene at 40 °C. The weak cation-exchange monoliths obtained provided good separation of a standard peptide mixture comprising four synthetic peptides designed specifically for the evaluation of cation-exchange columns. An equivalent separation was also achieved using the lowest capacity column studied, indicative of a high degree of robustness of the functionalization procedure. As well as demonstrably bearing ionic functional groups enabling analyte separation in the cation-exchange mode, the columns exhibited additional hydrophobic characteristics which influenced the separation process. The functionalized monoliths thus represent useful tools for mixed-mode separations.     

Ring-opening polymerization of cyclobutane adducts of tetracyanoethylene and vinyl ethers with tertiary amines

Ring-opening polymerizations of cyclobutane adducts of tetracyanoethylene (TCNE) and vinyl ethers (VE) or p-methoxystyrene with tertiary amines are described. The polymerization of the cyclobutane adduct 1a of TCNE and ethyl vinyl ether (EVE) was carried out with 10 mol % of triethylamine in acetonitrile at ambient temperature to afford the alternating copolymer of TCNE and EVE with high molecular weight in good yield under various conditions. Under the optimum condition, the cyclobutane adducts of TCNE and a variety of VEs such as n-butyl vinyl ether, isobutyl vinyl ether, 2,3-dihydrofuran, and 3,4-dihydro-2H-pyran were polymerized to yield similar polymers. Although the cyclobutane adduct 4 of TCNE and p-methoxystyrene did not polymerize under these conditions, the treatment of 4 with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in acetonitrile at 60°C gave the polymer. On the basis of the fact that the polymer molecular weight increased rapidly at the initial stage and slowly even after the consumption of all of monomers, we propose that the tertiary amine initiates the chain anionic polymerization of the cyclobutane adduct to afford an ammonium macrozwitterion 3 , which is subjected to the intermolecular nucleophilic substitution with each other in a step polymerization manner. © 1995 John Wiley & Sons, Inc.     

Ring-opening polymerization of cyclobutane adduct of dimethyl 1,1-dicyanoethylene-2,2-dicarboxylate and ethyl vinyl ether

For an extension of the work on the ring-opening polymerizations of cyclobutane adducts of strong donor olefins and strong acceptor olefins yielding novel alternating copolymers of those olefins, the ring-opening polymerization of the cyclobutane adduct 3 of dimethyl 1,1-dicyanoethylene-2,2-dicarboxylate (DDED) and ethyl vinyl ether (EVE) is investigated. Cyclobutane 3 reacted with methanol and acetic acid at ambient temperature to yield the corresponding ring-opened adducts. The polymerizations of 3 were carried out with anionic initiators, tertiary amines, ammonium halides, and Lewis acids, respectively, according to the polymerization methods of the cyclobutane adduct 1 of tetracyanoethylene (TCNE) and EVE. All these polymerization catalysts except for ammonium halides were effective for the polymerization of 3 , yielding alternating copolymers of DDED and EVE. The chain transfer reactions of the polymerization with anionic initiators are also discussed on the basis of a model reaction. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1563–1570, 1997     

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 (M _n = 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     

Acyclic diene metathesis (ADMET) depolymerization of functionalized furan-based polymers

Acyclic dience metathesis (ADMET) depolymerization of functionalized furan-based polymers prepared via aqueous ring-opening polymerization of 7-oxanobornenes has been investigated. Results indicate that while very high molecular weight poly [exo-N-methyl-7-oxabicyclo [2.2.1] hept-2,5-diene-2,3-dicarboximide] can be depolymerized to oligomers with ease, poly [2,3-dicarbomethoxy-7-oxabicyclo [2.2.1] hept-2,5-diene] is more resistant to depolymerization under similar conditions. This difference may be due to differential interaction of the carbonyls in the side chains with the metal atom of the catalyst in the proposed metallacyclobutane intermediate. ADMET depolymerization of poly [2,3-bis (trifluoromethyl)-7-oxabicyclo [2.2.1] hept-2,5-diene] was feasible, however, the extent of depolymerization was decreased due to the use of a coordinating solvent (THF) used during the depolymerization process. © 1994 John Wiley & Sons, Inc.     

Ring-opening metathesis polymerization of new α-norbornenyl poly(ε-caprolactone) macromonomers

Poly(ε-caprolactone) (PCL) macromonomers capped by a polymerizable norbornene end-group have been synthesized and (co)polymerized by ring-opening metathesis with formation of graft copolymers and polymacromonomers. α-Norbornenyl PCL macromonomers have been synthesized by ring opening polymerization (ROP) of ε-caprolactone (εCL) initiated by 2-diethylaluminoxymethyl-5-norbornene. Copolymerization of these PCL macromonomers with norbornene and polymerizable derivatives has been catalyzed by the [RuCl₂(p-cymene)]₂ PCy₃/(trimethylsilyl)diazomethane complex yielding a series of poly(norbornene)-graft-poly(ε-caprolactone) copolymers. These new graft copolymers have been characterized by a set of analytical methods, i.e., SEC, ¹H-NMR, FTIR, DSC, and TGA. Furthermore, PCL macromonomers have been polymerized into high molecular weight comb chains of narrow molecular weight distribution (M_w/M_n = 1.10) within high yields (90%). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2447–2455, 1999     

Anionic polymerization of 4-methyl-2-oxetanone (β-butyrolactone)

Polymerization of 4-methyl-2-oxetanone ( 1 ) initiated with potassium acetate-dibenzo-18-crown-6 complex ( 2 ) in THF as solvent, was studied. Transfer reactions, leading to both crotonate anions and carboxylic acid formation, have been observed. Two kinetic effects of these reactions, hampering the living polymerization, have been established. The first results from reinitiation with the crotonate anions and thereby lowers the polymer molecular weight. The second is the decrease in the overall polymerization rate due to complexation of the growing carboxylate anions with carboxylic acid moieties. Kinetic scheme of polymerization involves propagation accompanied by transfer followed by slow reinitiation. This scheme, including complexation of the active species has been solved numerically. The apparent rate and equilibrium constants (k_p, k_tr, k_ri, and K_ass and respectively) have been determined. Although these kinetic parameters depend strongly on the polymerization conditions, but the ratio of the rate constants k_p : k_t : k_ri is fairly constant and equal to 10⁻⁴ : 10⁻⁶ : 10⁻⁶, respectively (at 20°C). Conditions of the controlled anionic synthesis of the amorphous poly(4-methyl-2-oxetanone) with $\bar M_n$ as high as 1.7 × 10⁴ and ${{ \le \bar M_n } \mathord{\left/ {\vphantom {{ \le \bar M_n } {\bar M_n }}} \right. \kern-\nulldelimiterspace} {\bar M_n }} \le 1.20$ have also been elaborated.     

Contact metathesis polymerization (CMP)

Ring-opening metathesis polymerization (ROMP) has been used to investigate adhesive and coating formation via a general process called contact metathesis polymerization (CMP). This process involves applying a metathesis catalyst directly to the surface to be modified and initiating the polymerization by exposing this newly formed catalyst-coated surface to a monomer capable of undergoing ROMP, thereby creating an adhesive bond or coating. In this paper, we describe excellent primary adhesion results of bonding low surface energy elastomers to metals and themselves using ROMP as the operative chemistry. The elastomers natural rubber, EPDM, and Santoprene^® are difficult to bond using conventional methods, particularly in their post-vulcanized state. CMP yields rubber-tearing bonds to pre- and post-vulcanized elastomers at room temperature under ambient conditions in air, in the presence of moisture, and with minimal surface preparation using well-defined olefin metathesis catalysts.     

Ring-opening polymerization of octamethylcyclotetrasiloxane using 3d metal trifluoroacetate complexes

1. Download : Download high-res image (65KB)
2. Download : Download full-size image

     

Synthesis and characterization of poly(ethylene glycol) bottlebrush networks via ring-opening metathesis polymerization

Herein it is reported how the overlap concentration (C*) can be used to overcome crosslinking due to diol impurities in commercial poly(ethylene glycol) (PEG), allowing for the synthesize of bottlebrush polymers with good control over molecular weight. Additionally, PEG-based bottlebrush networks are synthesized via ring-opening metathesis polymerization, attaining high conversions with minimal sol fractions (<2%). The crystallinity and mechanical properties of these networks are then further altered by solvent swelling with phosphate buffer solution and 1-ethyl-3-methylimidazolium ethyl sulfate/dichloromethane cosolvents. The syntheses reported here highlight the potential of the bottlebrush network architecture for use in the rational design of new materials.