Cyclopentadienyl Nickel and Palladium Complexes/Activator System for the Vinyl‐Type Copolymerization of Norbornene with Norbornene Carboxylic Acid Esters: Control of Polymer Solubility and Glass Transition Temperature

Abstract

Summary: In non‐polar solvents such as toluene, Cp‐Ni and ‐Pd complexes (Cp = η5‐C5H5) with appropriate activators have been found to induce the addition polymerization of norbornene in excellent yields, for example (Cp)Pd(allyl)/[Ph3C][B(C6F5)4] gave 105 120 kg‐polymer/cat‐mol · h at room temperature. While the Cp‐Pd system was not suitable in the presence of ester‐substituted norbornenes, the Cp‐Ni system, for example (Cp)Ni(Cl)(PPh3)/AlMe3/B(C6F5)3 can copolymerize norbornene with 5‐norbornene‐2‐carboxylic acid methyl ester in toluene to give high yields (up to 68% in 2 h at room temperature) of copolymer with variable contents of the methyl ester monomer unit (17.4–60.7 mol‐%). These copolymers have high molecular weights ($\overline M _{\rm n}$ = 234 100–109 500) and narrow molecular weight distributions ($\overline M _{\rm w} /\overline M _{\rm n}$ = 1.78–1.89). In addition, they are soluble in common organic solvents giving flexible and transparent films on casting, that show very high Tg in the range of 352.8 to 316.0 °C. The same Ni‐catalyst system can also copolymerize norbornene derivatives with bulky substituents, i.e., 2‐butyl‐5‐norbornene and 5‐norbornene‐2‐carboxylic acid butyl ester. The Tg of these copolymers are lower (294.9–267.3 °C) than the methyl ester‐based copolymers, demonstrating that the Tg of the polynorbornene copolymer film can be tailored simply by changing the alkyl group of the monomer to within the range of 352 to 267 °C.Figure showing the addition polymerization of norbornene using Cp‐Ni complex with appropriate activators.magnified imageFigure showing the addition polymerization of norbornene using Cp‐Ni complex with appropriate activators.

Synthesis and Properties of Addition-Type Poly(norbornene)s with Siloxane Substituents

“…Monomers and polymers were characterized by 1 H NMR (300 MHz), 13 C NMR (75 MHz) in CDCl 3 and 29 Si NMR (60 MHz) in the solution containing C 6 D 6 , toluene and Cr(acetylacetonate) 3 as a shiftless relaxation reagent at 23 C with a JNM LA-300WB spectrometer. Compositions of the copolymers were calculated from 1 H NMR spectra, on the basis of the peak intensities originated from siloxane unit (see Figure 3).…”

“…[2][3][4][5][6][7][8][9][10][11][12][13] Heitz et al 2,3 investigated the addition-type copolymerizations of norbornene with norbornene carboxylic acid esters, and found that the solubility of the copolymers and the thermal properties, such as glasstransition and decomposition temperatures, were dependent on the content as well as structure of the substituents. Risse et al [4][5][6] came to the same conclusion by studying poly-(norbornene)s containing hydroxyl, carboxylic acid and ester.…”

Addition-type poly(norbornene)s with siloxane substituents: synthesis, properties and nanoporous membrane

“…This system is already known to be an active catalyst for addition polymerization of NB and its derivatives. 11,12 Table 1 lists the results of polymerizations that were carried out in toluene. Under these conditions, the catalytic system efficiently initiated homo-and copolymerizations of the NBs.…”

“…So far, many types of poly(norbornene)s with functional pendant groups have been investigated. [1][2][3][4][5][6][7][8][9][10][11][12][13] Previously, we prepared the addition-type poly(norbornene)s with siloxane (Si-O-Si) linkages, which showed improved solubility and mechanical flexibility. 13 In addition, the film for the polymer with Si(OSiMe 3 ) 3 groups was found to display high oxygen permeability (P(O 2 )¼39-239 Barrer), depending on the side group content.…”

Nickel(II) complexes bearing the bis(β‐ketoamino) ligand for the copolymerization of norbornene with a higher 1‐alkene

“…In addition, the materials exhibit poor processability because of their high T g values. 8 To improve their properties, a series of copolymers of NB with ethylene, 9,10 propylene, 11,12 NB derivatives, [13][14][15] and polar-group-terminal olefin monomer, 16 have also been studied. On the other hand, only a few articles have reported the copolymerization of NB and a higher 1-alkene.…”