Polynorbornene, polymerization

The polynorbornenes X bearing cyclotriphosphazenes with -0(CH2CH20)x-CH3 (x=l, 2,3,7.2) side groups have been prepared via ring opening metathesis polymerization (ROMP) and complexed with LiS03Cp3 and LiN(S02Cp3)2 (10-60% molar ratios) by Allcock [619,620]. 

The first report of ROMP activity by a well-characterized Mo or W species was polymerization of norbornene initiated by W(CH-t-Bu)(NAr)(0-f-Bu)2 [122]. In the studies that followed, functionality tolerance, the synthesis of block copolymers, and ring-opening of other monomers were explored [30, 123]. Two important issues in ROMP concern the cis or trans nature of the double bond formed in the polymer and the polymer s tacticity. Tacticity is a consequence of the presence of two asymmetric carbons with opposite configuration in each monomer unit. The four ROMP polymers (using polynorbornene as an example) that have a regular structure are shown in Scheme 3. 

Scheme 3. The four possible regular structures of polynorbornene prepared by ring-opening metathesis polymerization...

Functionalized polynorbornene derivatives, (V), prepared by Liaw et al. (4) using ring-opening metathesis polymerization exhibited strong carbazole fluorescence. Monomer emissions occurred in the near ultraviolet (UV) at approximately 380 nm and extended into the blue-violet region at 330 nm. 

A patent by A. W. Anderson et al. (Du Pont) disclosed the first transition metal catalyzed polymerization of a cyclic olefin in 1955 [1]. Subsequent to the discovery of Ziegler-Natta polymerization [2] norbornene was found to polymerize in the presence of the catalyst systems TiCl /EtMgBr. Eleuterio [3 a] and Truett et al. [3 b] obtained polynorbornene by using transition metal catalysts based on Mo and Ti, respectively. IR-studies and ozonolysis of the polymer revealed the presence of carbon-carbon double bonds, indicating that polymerization had occured by unexpected ring opening Eq. 1 [3]. 

The DIPP tantalacyclobutane complex, 32a, has been shown to polymerize excess norbornene at 50 °C to yield polynorbornene with a molecular weight... 

The catalytic activity for olefin polymerization was evaluated for complex 17a. High molecular weight addition-type polynorbornene (PNB) with a moderate molecular weight distribution (Mw = 106, Mw/Mn = 2.3-3.5) was obtained when 17a was activated with MAO. The activity was highest at 80 °C (107 g of PNB/(mol of Ni) h 1) resulting from an increase in the concentration of active catalyst centers at that temperature. However, further increases in temperature led to catalyst decomposition rather than higher turnover numbers. 

Norbornene and norbornene methyl ester have been polymerized forming a polymer that lacks backbone carbon-carbon double-bond unsaturation. The polymerization catalyst mixture consisted of palladium acetate, a phosphine such as tricyclohex-ylphosphine, a Lewis acid such as dimethyl zinc, and hexafluoroisopropanol. Polynorbornenes prepared in this manner typically had M s> 200,000 daltons with polydispersies less than 2, while poly(norbornene methyl ester) had M s of roughly 100,000 daltons. 

Norbornene polymerization CdF Chimie Elf Atochem operated since 1976 Nippon Zeon 2 steps operated since 1991 norbornene norbornene polynorbornene (Norsorex ) hydrogenated norbornene (Zeonex ) RuCls/HCl/BuOH 25-100°C... 

A series of polynorbornenes containing the second generation dendron D2 as a side group (R = C11H21), with different degrees of polymerization were also synthesized [262,263]. They exhibit a nematic (over 2 °C), two SmA and a hexatic B phase on cooling from the isotropic liquid (which occurs at around 100 °C). 

The most common polymer supports used for chiral catalyst immobilization are polystyrene-based crosslinked polymers, although poly(ethylene glycol) (PEG) represents an alternative choice of support. In fact, soluble PEG-supported catalysts show relatively high reactivities (in certain asymmetric reactions) [le] which can on occasion be used in aqueous media [le]. Methacrylates, polyethylene fibers, polymeric monoliths and polynorbornenes have been also utilized as efficient polymer supports for the heterogenization of a variety of homogeneous asymmetric catalysts. 

Concurrent with the development of the mechanistic explanations for the chemistry has been the creation of new polymers based on ROMP chemistry. While a wide variety of strained cyclic monomers have been polymerized with a significant emphasis on monomer structure/reactivity relationships, three ring structures deserve special attention, since they are or have been produced on a commercial scale. These polymers are polyoctenamer (from cyclooctene), polynorbornene (from... 

Antibiotic-resistant bacteria cause life-threatening infections in hospitals and society in general. There is a vital requirement to develop new antimicrobial agents, but this task involves extensive scientific trials. This chapter reviewed broad-spectrum polymeric antimicrobials, which are not susceptible to current resistance, and mechanisms of bacteria to mimic the antimicrobial action of natural HDP, which exert their effect by permeabilising the bacterial cytoplasmic membrane. Most cationic antimicrobial polymers appear to work in a manner similar to membrane-active AMP, such as magainin. The design and synthesis of different polymers, such as methacrylate-based copolymers, PPE, polynorbornene by-products, amphiphilc arylamide polymers and large polymers, have been studied as biomimetic polymers in different applications. 

More recently, Matyjaszewski [132] and others [133,134] reported general methods of the transformation of living ROMP into ATRP and anionic polymerization. In this approach, polynorbornene (PNB) and poly(dicyclopentadiene) (PGP) with terminal bromide were synthesized by end-capping of the corresponding hving chain ends with benzyl bromide (Scheme 11.32). 

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