Metathesis Polymerization Of Cyclooctene Research Articles

Covalently Crosslinked Networks from Telechelic Polycyclooctene with Reinforced Properties

Comprehensive SummaryIntroducing covalently crosslinked network to telechelic polymers can enable the formation of advanced polymeric materials with enhanced material properties. In this contribution, well‐defined telechelic polymers bearing acetoacetate groups were synthesized via Ru‐catalyzed ring‐opening metathesis polymerization of cyclooctene in the presence of chain transfer agents. Given the unique feature of muti‐site reactive acetoacetate end groups, several crosslinked networks were constructed using different crosslinkers under mild conditions. In the Michael addition reaction system, the introduction of di/trifunctional aliphatic acrylate as crosslinkers significantly enhanced the mechanical properties of the generated crosslinked network (tensile strength up to 27 MPa, elongation at break up to 500%). On the other hand, vitrimers with dynamic covalent crosslinked networks were accessed via transamination of vinylogous urethane reaction using telechelic polymers and tris(2‐aminoethyl)amine. These vitrimers presented great mechanical properties and reprocessing properties. These strategies can be potentially applied to construct other types of high‐performance polymeric materials.

Regularities of ring-opening metathesis polymerization of cyclooctene in the presence of molybdenum catalysts

At the initial stages the polymerization of cis-cyclooctene in the bulk with the catalysts Me3C-CH=Mo(NAr)(OCMe2CP3)2, PhMe2C-CH=Mo(NAr)(OCMe2CP3)2, Me3Si-CH=Mo(NAr)(OCMe2CP3)2, and PhMe2Si-CH=Mo(NAr)(OCMe2CP3)2 predominantly affords cis-polyoctenamers. The content of the trans- units in the polymer increases with an increase in the conversion. The sharpest increase in the trans- unit content observed for conversions higher than 80% is related to secondary metathesis reactions. The number-average molecular weights of the polymers increase linearly with the conversion. At conversions above 80% the molecular weights decrease due to the increasing contribution of chain transfer reactions. Polyoctenamers with the increased content of trans- units crystallize in two modifications.

Synthesis, structure, and catalytic properties of heteroelement carbene tungsten complexes Ph3ECH=W(OBu-t)2(OPh)2 (E = Si, Ge)

Novel silicon- and germanium-containing tungsten complexes Ph3ECH=W(OBu-t)2(OPh)2 were synthesized by the reaction of carbyne derivatives Ph3EC≡W(OBu-t)3 (E = Si, Ge) with phenol and isolated in high yields. Their structure was determined by X-ray diffraction. Individual complexes do not exhibit catalytic activity, whereas in the presence of AlBr3 they initiate metathesis polymerization of cyclooctene.

Synthesis and catalytic properties of polynuclear molybdenum silicon-containing carbene complexes

The molybdenum silicon-containing carbene complexes PhMe2Si—CH=Mo(NAr)(OR)2 (1), Ph2Si[CH=Mo(NAr)(OR)2]2 (2), and (RO)2(ArN)Mo=CH—(SiMe2)2—CH=Mo(NAr)(OR)2 (Ar = 2,6-Pri2C6H3; R = CMe2CF3) were synthesized by the reaction of the R′— CH=Mo(NAr)(OR)2 compounds (R′ = But or PhMe2C) with silicon-containing vinyl reagents. The structures of complexes 1 and 2 and the known PhMe2C—CH=Mo(NAr)(OCMe2CF3)2 compound were established by X-ray diffraction. The catalytic properties of the silicon-containing carbene complexes in homometathesis of hex-1-ene and metathesis polymerization of cyclooctene were studied. The catalytic activity of these complexes and the stereoregularity of the resulting polyoctenamers substantially depend on the nature of the substituent at the carbene carbon atom.

ABA triblock copolymers with a ring‐opening metathesis polymerization/macromolecular chain‐transfer agent approach

AbstractBlock copolymers containing polystyrene and polycyclooctene were synthesized with a ring‐opening metathesis polymerization/chain‐transfer approach. Polystyrene, containing appropriately placed olefins, was prepared by anionic polymerization and served as a macromolecular chain‐transfer agent for the ring‐opening metathesis polymerization of cyclooctene. These unsaturated polymers were subsequently converted to the corresponding saturated triblock copolymers with a simple heterogeneous catalytic hydrogenation step. The molecular and morphological characterization of the block copolymers was consistent with the absence of significant branching in the central polycyclooctene and polyethylene blocks [high melting temperatures (114–127 °C) and levels of crystallinity (17–42%)]. A dramatic improvement in both the long‐range order and the mechanical properties of a microphase‐separated, symmetric polystyrene–polycyclooctene–polystyrene block copolymer sample was observed after fractionation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 361–373, 2007

Bis‐dendritic polyethylene prepared by ring‐opening metathesis polymerization in the presence of bis‐dendritic chain transfer agents

AbstractThe synthesis of ABA triblock copolymers is described, in which the A blocks are poly(benzyl ether) dendrons and the B block is polycyclooctene or polyethylene. Bis‐dendritic cis‐olefins were synthesized and used as chain transfer agents in ring‐opening metathesis polymerization of cyclooctene in a process that inserts the dendrons at the polymer chain‐ends. Evaluation of the polymer products by spectroscopic, chromatographic, and titration methods supports their triblock structure. Hydrogenation of the unsaturated polycyclooctene B‐block of these ABA triblock copolymers provides the first reported synthesis of bisdendritic polyethylene. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5429–5439, 2005

Bulk Metathesis Polymerization of Cyclooctene

Abstract The bulk ring-opening metathesis polymerization (ROMP) of cyclooctene initiated with the WCI6/Sn(CH3)4 catalytic system was investigated at 40, 100, and 160°C using high vacuum techniques. The polymerizations were followed over a period of several days. Detailed analyses of the polymerization products by gel permeation chromatography (GPC) and 1H and 13C NMR were carried out. Along with unsaturated high molecular weight (HMW) polymer (polyoctenamer), low molecular weight (LMW) polymer was found, the proportion of the latter increasing with time. The LMW fraction contains saturated LMW polymer together with ring polymer. The results are explained in terms of kinetic and thermody-namic arguments.

Catalyst activation in the metathesis polymerization of cyclooctene

AbstractThe addition of unsaturated organic halides during the metathesis polymerization reaction of cyclooctene, using a WCl6/diisobutylaluminium chloride/2,6‐di‐tert‐butyl‐4‐methylphenol catalyst, was found to cause instantaneous conversion of the unreacted monomer to polymer. Both 1,2‐dichloroethene and 1,6‐dibromo‐3‐hexene were found to be very effective for this purpose. When 1,4‐dichloro‐2‐butene was added during the reaction, unusual and unexplained products were obtained, but when it was added to the catalyst before the start of the reaction a very fast polymerization occurred yielding high molecular weight polymers. Changes in polymer melting points with reaction time suggested that isomerization occurred after polymerization and that the initial polymers formed had slightly blocky, trans unit sequences.