Cycloolefin copolymer

Table 9 compares the most important properties of substrate materials based on BPA-PC, PMMA, and CPO (three different products) (216,217). The future will prove if the current disadvantages of CPO against BPA-PC regarding warp, processibiUty (melt viscosity), and especially cost can be alleviated. CycHc polyolefins (CPO) and, especially cycloolefin copolymers (COC) (218) and blends of cycloolefin copolymers with suitable engineering plastics have the potential to be interesting materials for substrate disks for optical data storage. 

Since the last edition several new materials have been aimounced. Many of these are based on metallocene catalyst technology. Besides the more obvious materials such as metallocene-catalysed polyethylene and polypropylene these also include syndiotactic polystyrenes, ethylene-styrene copolymers and cycloolefin polymers. Developments also continue with condensation polymers with several new polyester-type materials of interest for bottle-blowing and/or degradable plastics. New phenolic-type resins have also been announced. As with previous editions I have tried to explain the properties of these new materials in terms of their structure and morphology involving the principles laid down in the earlier chapters. 

The first documented example of the living ROMP of a cycloolefin was the polymerization of norbornene using titanacyclobutane complexes such as (207) 510-512 Subsequent studies described the synthesis of di- and tri-block copolymers of norbornenes and dicyclopentadiene.513 However, functionalized monomers are generally incompatible with the highly electrophilic d° metal center. 

Amorphous polymers are characterized by the following properties They are transparent and very often soluble in common organic solvents at room temperature. The following amorphous polymers have gained industrial importance as thermoplastic materials polyfvinyl chloride), polystyrene, polyfmethyl methacrylate), ABS-polymers, polycarbonate, cycloolefine copolymers, polysulfone, poly( ether sulfone), polyfether imide). 

High magnetic fields and in particular C-NMR spectroscopy allow the analysis of even longer configurational sequences (tetrads up to nonads). This proved to be important in particular for the analysis of polyolefins like polypropylene or cycloolefin copolymers (COC). These polymers are available via transition-metal mediated (Ziegler-Natta, metallocene) insertion polymerizations, and the configurational analysis provides deep insight into the respective polymerization mechanisms as well as into the structure-property relationships. 

H. Cherdron, M.-J. Brekner, R Osan, Cycloolefin Copolymers, Angew. Makromol. Chem. 223, 121 (1994)... 

For example, it is possible to synthesize isotactic as well as syndiotactic polypropylene in high configurational purity and high yields. The same holds for syndiotactic polystyrene. Furthermore, metallocene catalysts open the possibility to absolutely new homopolymers and copolymers like, e.g., cycloolefin copolymers (COG) and even (co)polymers of polar monomers.The simplest metallocene catalyst consists of two components. The first one is a n-complex (the actual metallocene) that can be bridged via a group X and therefore can become chiral ... 

Depending on the application, different demands are placed on the melt viscosity of the polymer. For injection molding applications, lower melt viscosities are required than for extrusion applications. For a given comonomer composition and processing temperature, the melt viscosity of the cycloolefin copolymers increases with the mean molecular weight. 

An example of such a catalyst system is racemic isopropylene bis(l-indenyl) zirconium dichloride in combination with an alumi-noxane (21). The reaction is carried out in hydrocarbon solvents, e.g., toluene. A solution of norbornene in toluene with the catalyst is degassed and then pressurized with ethene. The polymerization is carried out while stirring at 70°C under constant ethylene pressure at 18 bar. After completion, the polymer is precipitated in acetone and filtered (21). The cycloolefin copolymers obtained in this way have a high thermal shape stability and it is possible to use the polymers as thermoplastic molding compositions. 

Addition copolymers of cycloolefin compounds with a polar substituents in the side chain exhibit excellent heat resistance and transparency. They are also capable of crosslinking to improve the adhesion properties, the dimensional stability and the chemical resistance (35). 

K. Ohkita, T. Imamura, and N. Oshima, Cycloolefin copolymer formed by ring-opening polymerization, process for producing the same, and optical material, US Patent 7056999, assigned to JSR Corporation (Tokyo, JP), June 6,2006. 

T. Weller, F. Osan, F. Kuber, and M. Aulbach, Process for preparing cycloolefin copolymers, US Patent 5698645, assigned to Hoechst Ak-tiengesellschaft (Frankfurt, DE), December 16,1997. 

D.A. Hammond and D. Heukelbach, Cycloolefin copolymer resins having improved optical properties, US Patent 6951898, assigned to Ticona LLC (Summit, NJ), October 4,2005. 

T. Penttinen, K. Nevalainen, and J. Jarvinen, Method for manufacturing heat-sealable packaging material having barrier layer containing cycloolefin copolymer, US Patent 7 344 759, assigned to Stora Enso Oyj (Helsinki, FI), March 18, 2008. 

R.D. Jester, Cycloolefin copolymer heat sealable films, US Patent 7288316, assigned to Topas Advanced Polymers, Inc. (Florence, KY), October 30, 2007. 

M. Donner and W. Kaminsky, Chemical recycling of cycloolefin-copolymers (COC) in a fluidized-bed reactor, /. Anal. Appl. Pyrolysis, 74 (l-2) 238-244, August 2005. 

Cyclic Polyolefins (CPO) and Cycloolefin Copolymers (COC). Japanese and European companies are developing amorphous cyclic polyolefins as substrate materials for optical data storage (213—217). The materials are based on dicyclopentadiene and/or tetracyclododecene (10), where R = H, alkyl, or COOCH3. Products are formed by Ziegler-Natta polymerization with addition of ethylene or propylene (11) or so-called metathesis polymerization and hydrogenation (12), (101,216). These products may still contain about 10% of the dicyclic structure (216). 

In the early 1990s supported metallocenes were introduced to enable gas phase polymerisation. Also ethene/a-olefin copolymers with high comonomer content, cycloolefin copolymers and ethene-styrene interpolymers became available. In 1990 Stevens at Dow [22] discovered that titanium cy-clopentadienyl amido compounds (constrained geometry catalysts) are very beneficial for the copolymerisation of ethene and long-chain a-olefins. 

Alternating copolymers have been obtained by copolymerisation of ethylene and cycloolefins (using a large excess of cycloolefin) in the presence of vanadium-based Ziegler-Natta catalysts such as V(Acac)3-AlEt2Cl and VC14 AlEt2Cl ... 

Only cycloolefins with rings containing an odd number of carbon atoms, such as cyclopentene (x = 3) and cycloheptene (x = 5), yield crystalline copolymers with an erythro-diisotactic configuration. Cycloolefins with an even number of carbon atoms in the ring, such as cyclobutene (x = 2) and cyclooctene (x = 6), give amorphous copolymers [241]. 

The rate of copolymerisation of ethylene and odd-membered ring cycloolefins is higher than the rate of copolymerisation involving even-membered cycloolefins [467]. This indicates that both the polymerisation kinetics and the spatial configuration of the copolymer are influenced by steric factors [2]. 

Metallocene catalysts show low r values, which allows easy incorporation of bulky cycloolefins into the growing copolymer chain. Surprisingly, the ethylene reactivity ratio in copolymerisation with cyclopentene in the presence of a (ThindCH2)2ZrCl2-based catalyst (r = 2.2) and in copolymerisation with norbornene in the presence of catalysts characterised by Cs and Ci symmetry (ri 3.4 and 3.1 respectively) is considerably lower than that for the copolymerisation of ethylene with propylene (r = 6.6 at 37 °C). Various catalysts produce copolymers of structures that are between statistical and alternating [468]. 

Preferred olefins in the polymerisation are one or more of ethylene, propylene, 1-butene, 2-butene, 1-hexene, 1-octene, 1-pentene, 1-tetradecene, norbornene and cyclopentene, with ethylene, propylene and cyclopentene. Other monomers that may be used with these catalysts (when it is a Pd(II) complex) to form copolymers with olefins and selected cycloolefins are carbon monoxide (CO) and vinyl ketones of the general formula H2C=CHC(0)R. Carbon monoxide forms alternating copolymers with the various olefins and cycloolefins. 

Analogously to ethylene-carbon monoxide copolymers, alternating copolymers between cycloolefins such as norbornene and carbon monoxide have been synthesised using cationic Pd(II) complexes modified by phosphorus ligands such as [Pd(MeCN)n(PPh)4 J[BF4]2( = 1,2,3) [27]. General requirements for the... 

Alternating copolymers of cycloolefins and carbon monoxide have also been obtained in the case of cyclopentene the copolymerisations were run using cationic Pd(II) complexes modified by an achiral l,3-bis(diphenylphosphino)-propane ligand or a chiral 2,4-bis(diphenylphosphino)pentane ligand. 

---