Acyclic diene metathesis polymerization polymers

Keywords Acyclic diene metathesis polymerization, ADMET, Condensation polymerization Functionalized polymers, Negative neighboring group effect, Branched polyethylene... 

K. Nomura, H. Morimoto, Y. Imanishi, Z. Ramhani, and Y. Geerts, Synthesis of high molecular weight rra i-poly(9,9-di- -octylfluorene-2,7-vinylene) by the acyclic diene metathesis polymerization using molybdenum catalysts, J. Polym. Sci., Part A Polym. Chem., 39 2463-2470, 2001. 

Acyclic diene metathesis polymerization (ADMET) is a related polymerization in which an unconjugated diene polymerizes with loss of ethene [Lehman and Wagener, 2002, 2003 Schwendeman et al., 2002], ADMET is carried out using the Schrock and Gmbbs initiators at about 40-80°C. The process is a step polymerization, not a ROP chain reaction. The reaction is reversible, and high polymer MW is achieved by removal of ethene (usually by reduced... 

Dienes are cyclized by intramolecular metathesis. In particular, cyclic alkenes 43 and ethylene are formed by the ring-closing metathesis of the a,co-diene 46. This is the reverse reaction of ethenolysis. Alkene metathesis is reversible, and usually an equilibrium mixture of alkenes is formed. However, the metathesis of a,co-dienes 46 generates ethylene as one product, which can be removed easily from reaction mixtures to afford cyclic compounds 43 nearly quantitatively. This is a most useful reaction, because from not only five to eight membered rings, but also macrocycles can be prepared by RCM under high-dilution conditions. However, it should be noted that RCM is an intramolecular reaction and competitive with acyclic diene metathesis polymerization (ADMET), which is intermolecular to form the polymer 47. In addition, the polymer 47 may be formed by ROMP of the cyclic compounds 43. 

A new acyclic diene metathesis polymerization method has been developed using 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene)benzylidene mthenium(II) dichloride as catalyst. This reaction catalyst was used for preparing oligomers and polymers containing amino acids or polypeptides. 

ROMP Ring-opening metathesis polymerization ADMET Acyclic diene metathesis polymerization ALTMET Alternating diene metathesis polycondensation MCLCP Main chain liquid crystalline polymer SCLCP Side chain liquid crystalline polymer mru molecular repeating unit... 

Fig. 14 Acyclic diene metathesis polymerization of 9 to give polymer 10.

Olefin metathesis (OM) has proven to be one of the most important advances in catalysis in recent years based on the application of this chemistry to the synthesis of polymers and biologically relevant molecules [1-10]. This unique transformation promotes chain and condensation polymerizations, namely ring opening metathesis polymerization and acyclic diene metathesis polymerization (ADMET). Applications of metathesis polymerization span many aspects of materials synthesis from cell-adhesion materials [11] to the synthesis of linear polyethylene with precisely spaced branches [12]. 

Intermolecular metathesis reactions, such as eqn. (8), lead eventually to high polymers and proceed very cleanly when initiated by metal carbene complexes these are known as ADMET acyclic diene metathesis) polymerizations see Ch. 8. 

A large number of applications involve the synthesis of polymers by either ring-opening metathesis polymerization (ROMP), which transforms cyclic olefins into unsaturated polymers (Fig. 4.14) [46,47], or acyclic diene metathesis polymerization (ADMET), which converts acyclic olehns into polymers (Fig. 4.15)... 

The metathesis reaction may be used to produce a range of polymers by two processes (Scheme 10). Cyclic olefins with a threshold level of ring strain can be polymerized via ROMP chain process. Under appropriate conditions, certain acyclic dienes can be polymerized in a condensation process known as acyclic-diene metathesis polymerization, or ADMET. The elimination of a volatile olefin byproduct (usually ethylene) provides a driving force for the latter process, while alleviation of ring strain is the primary driver in ROMP. Because ADMET is a condensation... 

Using the above monomers several polymers have been prepared. Thus, monomer 46 has been polymerized by the acyclic diene metathesis polymerization method (ADMET) by using Grubb s catalyst to afford medium-molecular-weight polymers [41]. On the other hand, the reaction of the di-chloro derivative 42 with NaO- C6H4- -S02-C6H4-/7-0Na yields the polymer 49 (Fig. 4.23). Similarly the monomer 47 has been used in condensation polymerization with hexamethylenediisocyanate to afford the polyurethane 50. Polyimides such as 51 have been prepared by using monomer 48. 

POLYMERS BEARING METALLOCENE MOIETIES BY RING-OPENING METATHESIS POLYMERIZATION OR ACYCLIC DIENE METATHESIS POLYMERIZATION... 

The metathesis reaction is a versatile tool with a variety of applications in both polymer chemistry and organic synthesis. The basie metathesis reactions inelude ring-closing metathesis (RCM), eross-metathesis (CM), ring-opening metathesis (ROM), acyclic diene metathesis polymerization (ADMET), and ring-opening metathesis polymerization (ROMP) (Scheme 2). 

Acyclic diene metathesis polymerization (ADMET) polymerization leads to polymers with precisely defined microstruetures and, hence, to excellent models to study the crystallization behavior of highly branehed ethylene copolymers. With ADMET, variation in the monomer structure gives access to a broad range of precisely defined polymers, allowing direet correlation of structure-property relationships. This clean polycondensation ehemistry is used here to produce a branched architecture characterized by the preeise branch placement every n fixed mefliylene units according to the following structural repeating unit ... 

Montero de Espinosa L, Ronda JC, Galia M, Meier MAR. 2009. Fatty Acid Derived Phosphorus-Containing Polyesters via Acyclic Diene Metathesis Polymerization. J Polym Sci Part A Polym Chem 47 5760-5771. 

A-A/B-B monomers, polycondensations, 157 A-B monomers, polycondensations, 157 AB monomers, self-polymerization via benzimidazole-activated ether synthesis, 266--274 Acetophenones Ru-catalyzed addition, 67-69 Ru-catalyzed step-growth copolymerization with a,(0-dienes for high-molecular-weight polymer synthesis, 99-112 4-(Acryloxy)benzoic acid, ordered polymer synthesis, 442-450 Acyclic diene metathesis polymerization cycle, 116,118/... 

Kreye and coworkers have utilized CIC lx in their U-4CR for the synthesis of a,fi)-diene monomer 213 (Scheme 7.72) [85]. Employing an acyclic diene metathesis polymerization strategy, the monomers were subsequently polymerized using the second-generation Hoveyda-Gmbbs catalyst in the presence of 1,4-benzoquinone (1,4-BQ) as an additive to obtain compound 214. Hydrogenation followed by the treatment with pyridiniump-toluenesulfonate provided the A -acylindole intermediate 215. Under various conditions, 215 provided polymers containing amide and acid (216,217, and 218) functionalities that can be useful for further modification of the side chain. This method clearly exemplifies that judicious application of IMCRs can lead to a new era in polymer synthesis. 

Apart from cross-metathesis, ROMP, and RCM, there are other less common metathesis reactions. These are acyclic diene metathesis polymerization (ADMET), ring-opening cross-metathesis (ROCM), ring-rearrangement metathesis (RRM), and ethenolysis. A general ADMET reaction is shown by reaction 7.3.1.7. ADMET reactions are generally performed on a,well-defined and strictly linear polymers with unsaturated polyethylene backbones. Ethenolysis is the cross-metathesis of ethylene with an internal olefin. 

Acyclic diene molecules are capable of undergoing intramolecular and intermolec-ular reactions in the presence of certain transition metal catalysts molybdenum alkylidene and ruthenium carbene complexes, for example [50, 51]. The intramolecular reaction, called ring-closing olefin metathesis (RCM), affords cyclic compounds, while the intermolecular reaction, called acyclic diene metathesis (ADMET) polymerization, provides oligomers and polymers. Alteration of the dilution of the reaction mixture can to some extent control the intrinsic competition between RCM and ADMET. 

Nearly all of the polymers produced by step-growth polymerization contain heteroatoms and/or aromatic rings in the backbone. One exception is polymers produced from acyclic diene metathesis (ADMET) polymerization.22 Hydrocarbon polymers with carbon-carbon double bonds are readily produced using ADMET polymerization techniques. Polyesters, polycarbonates, polyamides, and polyurethanes can be produced from aliphatic monomers with appropriate functional groups (Fig. 1.1). In these aliphatic polymers, the concentration of the linking groups (ester, carbonate, amide, or urethane) in the backbone greatly influences the physical properties. 

Olefin metathesis, an expression coined by Calderon in 1967,1 has been accurately described in Ivin and Mol s seminal text Olefin Metathesis and Metathesis Polymerization as the (apparent) interchange of carbon atoms between a pair of double bonds (ref. 2, p. 1). This remarkable conversion can be divided into three types of reactions, as illustrated in Fig. 8.1. These reactions have been used extensively in the synthesis of a broad range of both macromolecules and small molecules3 this chapter focuses on acyclic diene metathesis (ADMET) polymerization as a versatile route for the production of a wide range of functionalized polymers. 

K. B. Wagener, Acyclic Diene Metathesis (ADMET) Polymerization, in Synthesis of Polymers, A. D. Schluter (Ed.), Materials Science and Technology Series, Wiley, Weinheim, 1999. 

Wolfe and Wagener have developed main-chain boronate polymers (59) (Fig. 38) by the acyclic diene metathesis (ADMET) polymerization of symmetrical ,oj-dienes, containing both methyl- and phenyl-substituted boronate functionalities using Mo and Ru catalysts.84 The ring-opening metathesis polymerization (ROMP) of several norbornene monomers containing methyl- and phenyl-substituted boronates into... 

However, the regio-random distribution of functional groups can be avoided by an acyclic diene metathesis (ADMET) polymerization technique using symmetric monomers (33). The molecular weights of these polymers are restricted to < 3 x 104 Dalton by ADMET. Due to their rich hydrocarbon content, the barrier properties in final ethylene vinyl alcohol copolymers are reduced. 

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