Monomer meaning

The asymmetric substitution pattern of most monomers means that addition gives rise to a chiral center and their polymers will have tacticily (Section 4.2). 

Conversion of all hexose monomers, meaning glucose, galactose, and mannose. 

The kinetic analysis here is based on quantitative considerations of the ideal emulsion polymerization systems which have been described qualitatively in the preceding sections. The treatment centers only around stage I and stage II (Fig. 6.18), as no general theory for stage III is available. The treatment applies to styrene-like monomers, meaning those monomers with low water solubility and those in which monomer and polymer are completely miscible over all ranges of composition. 

The monomer mean-square displacement can be observed direcdy in computer simulations. It also enters in calculations for the coherent and incoherent dynamic structure factors. Most generally, we can consider a ftmaion ... 

Figure 26 Main results for the Rouse model with constraints. Symbols correspond to grid parameter j=1 with chain iengths /V=16,32,64,128, whereas p=2 results are shown by lines for N=32,64,128,256. The four panels show monomer mean-square displacement (a) and (c), end-to-end relaxation (b), and stress relaxation (d).

Mer is derived from the Greek word meros meaning part. Therefore, a monomer means one part or one unit dimer means two units oligomer means a few units and polymer means many units. A polymerization involves the reaction of a monomer to connect many monomer units. If the reaction is additive, where one monomer adds to the next as in the polymerization of styrene, the polymer is called an addition polymer. Polymerizations of olefins, such as ethylene, propylene, vinyl chloride, or styrene, are addition polymerizations. In an addition polymer, all of the atoms of the monomer remain in the polymer. If the monomers are connected in a condensation reaction such as when a carboxylic acid and an alcohol react to remove water and form an ester linkage, then the polymer is called a condensation polymer. Recognize that in this type of polymer all of the monomer atoms are not incorporated into the final polymer. 

A series of three armed stars (7) was obtained by polycondensation of the acetylated triphenol 6 with ei er 3-acetoxybenzoic acid or its trimethylsilyl ester (eq. 6). When these polycondensadons were conducted at die same maximum reaction temperature (270 °C), it was found that the monomer with the free carboxyl group yields the higher molecular weights (viscosities) (Table 3). Since the maximum molecular weights are limited by the monomer/starcenter ratio, the lower viscosities obtained from the silylated monomer mean that the conversion was not complete. This conclusion was confirmed by the NMR spectroscopic detection of a... 

In Equation (13), z and <(iT refer to the monomer of species i while y is the apparent mole fraction of component i, where apparent means that dimerization has been neglected. 

The mean monomer density decreases with the increasing degree of polymerization. 

In amoriDhous poiymers, tiiis reiation is vaiid for processes tiiat extend over very different iengtii scaies. Modes which invoived a few monomer units as weii as tenninai reiaxation processes, in which tire chains move as a whoie, obey tire superjDosition reiaxation. On tire basis of tiiis finding an empiricai expression for tire temperature dependence of viscosity at a zero shear rate and tiiat of tire mean reiaxation time of a. modes were derived ... 

In the collapse phase the monomer density p = N/R is constant (for large N). Thus, the only confonnation dependent tenn in (C2.5.A1) comes from the random two-body tenn. Because this tenn is a linear combination of Gaussian variables we expect that its distribution is also Gaussian and, hence, can be specified by the two moments. Let us calculate the correlation i,) / between the energies and E2 of two confonnations rj ]and ry jof the chain in the collapsed state. The mean square of E is... 

These monomers provide a means for introducing carboxyl groups into copolymers. In copolymers these acids can improve adhesion properties, improve freeze-thaw and mechanical stability of polymer dispersions, provide stability in alkalies (including ammonia), increase resistance to attack by oils, and provide reactive centers for cross-linking by divalent metal ions, diamines, or epoxides. 

The formation of copolymers involves the reaction of (at least) two kinds of monomers. This means that each must be capable of undergoing the same propagation reaction, but is is apparent that quite a range of reactivities is compatible with this broad requirement. We shall examine such things as the polarity of monomers, the degree of resonance stabilization they possess and the steric... 

The vapor pressure ratio measures the intrinsic tendency of component 1 to enter the vapor phase relative to component 2. Likewise, ri measures the tendency of Mi to add to Mi - relative to M2 adding to Mi-. In this sense there is a certain parallel, but it is based on Mi - as a reference radical and hence appears to be less general than the vapor pressure ratio. Note, however, that ri = l/r2 means kn/ki2 = k2i/k22- In this case the ratio of rate constants for monomer 1 relative to monomer 2 is the same regardless of the reference radical examined. This shows the parallelism to be exact. 

At the other end of the commonly encountered range we find the product rjr2 1. As noted above, this limit corresponds to ideal copolymerization and means the two monomers have the same relative tendency to add to both radicals. Thus if rj = 10, monomer 1 is 10 times as likely to add to Mj- than monomer 2. At the same time r2 = 0.1, which also means that monomer 1 is 10 times as likely to add to M2 than monomer 2. In this case the radicals exert the same influence, so the monomers add at random in a proportion governed by the specific values of the r s. 

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