Ring-opening polymerization reactions

Even at the qualitative level of the discussion above, it is difficult to make predictions regarding the spontaneity of the ring-opening polymerization reaction (5.FF) ... 

Table 5.8 Values for AH and AS for the Ring-Opening Polymerization, Reaction (5.FF), for Monomers with the Indicated Values of 1...

Table 5.9 Some Typical Ring-Opening Polymerization Reactions...

Germanium-bridged [l]ferrocenophanes undergo a number of ring-opening polymerization reactions to yield ferrocene-containing polymers, and the versatility of this interconversion has been reviewed. A -GeMe2-... 

Several 0-protected aldonic acids and aldonolactones such as 16-21 have been used as monomers in polycondensation and ring opening polymerization reactions [32-34],... 

Uses. Furfural is primarily a chemical feedstock for a number of monomeric compounds and resins. One route produces furan by decarbonylation. Tetrahydrofuran is derived from furan by hydrogenation. Polytetramethylene ether glycol [25190-06-1] is manufactured from tetrahydrofuran by a ring opening polymerization reaction. Another route (hydrogenation) produces furfuryl alcohol, tetrahydrofurfuryl alcohol, 2-methylfuran, and 2-methyltetrahydrofuran. A variety of proprietary synthetic resins are manufactured from furfural and/or furfuryl alcohol. Other... 

Lithium bromide was a satisfactory ionic catalyst for the ring-opening polymerization reaction (Figure 2). The standard concentration of 0.258% gave good reaction. A lower concentration gave a slower reac-... 

The resulting substituted norbomenes can be interesting as monomers for addition or ring-opening polymerization reactions. 

The usual method for obtaining linear silicone polymers is by ring-opening polymerization reactions on cyclic... 

Cationic organozinc compounds are expected to be good catalysts for ring opening polymerization reactions of epoxides and lactones because the enhanced Lewis acidity (see Lewis Acids Bases) of the zinc center favors its coordination to the monomer. For example, Walker and coworkers have found that the cationic zinc substituted cyclopentadienyl complex [3,5-Me2C6H3CH2CMe2C5H4Zn(TMEDA)]+ [EtB(C6F5)3] is an active initiator species for the polymerization of cyclohexene oxide and e-caprolactone. ... 

Many papers have been published concerning the structure of the active centers in anionic and cationic ring-opening polymerization reactions of oxacyclic monomers. Recently, attention has been paid in our laboratory to the influence of the structure of complex carbonium salt initiators, especially of the dioxolanyllum salts used for initiating the cationic polymerization reactions of trioxane, tetrahydrofuran and dioxolane, on the course of the polymerization ( ). 

Another series of papers has focused on combining both ATRP and nitroxide-mediated polymerizations with condensation and ring-opening polymerization reactions [360-364]. Initial reports by Hawker et al. [360,365] and Jerome et al. [361] used concepts similar to those first put forth by Puts and Sogah and prepared initiators that were dual-headed and could be used for two different polymerization techniques without a transformation step. They found that identification and use of the proper conditions could allow for the simultaneous polymerizations of two different monomers by two different routes. 

Catalysts are often needed to facilitate ring-opening polymerization reactions. Although the Sg-S equilibration is believed to be a free-radical process, most ringopening polymerizations follow an ionic pathway ... 

Ring-opening polymerization reactions of several 2-substituted-2-oxazolines (i.e. 2-methyl, 2-ethyl, 2-nonyl, and 2-phenyl) in the presence of methyl tosylate as catalyst have been described by Schubert et al. (Scheme 14.14) [33-35]. The reactions were performed in the temperature range 80 to 200 °C inside a single-mode micro-wave reactor. In a typical run, 25 mL stock solutions of monomer-initiator-solvent were prepared before the polymerization. These stock solutions were divided among different reaction vials so each experiment was performed on a 1-mL scale. 

Polyethylenimine (PEI) is an integral polyelectrolyte that is available commercially, e.g., Polymin (BASF). It is formed by the ring-opening polymerization [reaction (28)] of ethyleneimine (aziridine). The resulting polyamine has about 50% of the expected secondary-amine functionality and about 50% primary and tertiary due to branching ... 

PREPARATIVE TECHNIQUES There are two different pathways (polycondensation and ring-opening polymerization) for preparation of PES. The first method leads to a polymer of relatively low molecular weight, whereas the ring-opening polymerization reaction can lead to high molecular weight polymers under particular circumstances. 

Epoxy resin-based materials are available for use as endodontic sealers [64], They set by a ring-opening polymerization reaction between hexamethylene tetratramine (Fig. 10.5), which is part of the powder component, and iiw-phenol resin monomer, which comprises the liquid component [13]. In addition to the reactive molecule, the powder contains bismuth oxide (50%) to impart radiopacity and titanium dioxide (5%) as a pigment. The powder also contains silver particles (10%) to make the set material anti-bacterial. 

FIGURE 3.39 Examples of cyclic monomers for enzyme-catalyzed ring-opening polymerization reactions. 

The ring-opening polymerization reactions depend upon thermodynamic and kinetic factors, and on the total molecular strain energies of the particular ring structures. Six-membered -valero-lactam is the most stable ring structure and most difficult to polymerize. Also, the presence of substituents increases the stability of the rings and decreases the ability to polymerize. 

Base-catalyzed ring-opening polymerization reactions of carboxyanhydrides also result in formations of polypeptides ... 

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