Polymer repeating unit

The polymer repeat unit arises from reacting together two different functional groups which usually originate on different monomers. In this case the repeat unit is different from either of the monomers. In addition, small molecules are often eliminated during the condensation reaction. Note the words usual and often in the previous statements exceptions to both statements are easily found. 

Actual polymer repeat units occupy finite volumes and therefore exclude other segments from occupying the same space. 

R Common name Polymer repeating unit Encyclopedia reference... 

Both the spectrum and dynamics of the transient PM change markedly upon C60 doping. The doping concentration is given in mol%, where 1 mol% doping is equal to one molecule per hundred polymer repeat units. The PM spectrum of pristine DOO-PPV film, measured at t=0, 100, and 1200 ns, are shown in Fig-... 

The gum-like co-substituted polymers VI have lower Tg than polymers VII, which form excellent films. The highest ionic conductivity at 25 °C reported for the VI and VII/LiN(S02CF3)2 complexes are 3.5x10" and 2.4x10 S cm" for VI (x=7.3 ) and VII (x=7.3) complexed with 0.328 and 0.5 mol salt/polymer repeat unit, respectively [604]. 

Polyalkenes form by linking carbon atoms in a free radical polymerization. The polymer structure is constructed by connecting monomer units. The polymerization process converts the bonds of the monomers to a bonds between polymer repeat units. 

Polymers in which the quarternary nitrogen atom is part of a five- or six-membered ring comprise the second class of polymers. The ring forms part of the polymer backbone as indicated by the second and third polymer repeat units given in Table I. The member of this class cited in several patents is poly(diallyldimethyl-ammonium chloride) abbreviated poly(DMDAAC). 

The third class of polymers contains one or more nitrogen atoms on a pendant sidechain in the polymer repeat unit (13,14). The nitrogen may or may not be quaternary. In addition to being swelling clay stabilizers, these polymers also stabilize nonswelling mineral fine particles. Limited molecular weight data ig available but molecular weight values from 50,000 to 1 X 10 daltons have been cited for various polymers. 

Hydrogenation. Hydrogenation of poly(5-methyl-l,4-hexadiene) was carried out with p-toluenesulfonyl hydrazide (20) in refluxing xylene (2il molar ratio of the hydrazide to the polymer repeat unit). 

The molar volume of the polymer repeat unit is Vu V, is the molar volume of the solvent, fi, is the volume Fraction of the solvent, and Xi is an interaction term defining how good the solvent is for the polymer. The term X is negative for very good solvents and goes to about 0.55 for the limiting... 

In the preparation of the MOPPV LB films, the polyion complex monolayer were formed by the adsorption of the precursor onto the anionic amphiphile monolayer (route b-2 in Fig.5) [36,37]. The monolayer of 2C12SUC was spread on a aqueous solution of the MOPPV precursor polymer (repeating unit concentration about 10"4 M). The monolayer was allowed to stand for 4 hours to adsorb the precursor after being compressed to a surface pressure of 30 mNm 1. The monolayer was deposited on fused quartz substrate by the LB technique. At last, the deposited polyion complex was converted to MOPPV by the heat treatment at 200 C in vacuo (about 10 2 torr). 

Generate polymer repeat units with minimum 2 groups and maximum 4 groups. 

Estimate the target properties for each generated polymer repeat units and eliminate those that do not match the target property values. For the remaining polymers, evaluate them in terms of the following selection criteria ... 

The polymer repeat unit with the smallest value is the best polymer, in this simple polymer design problems. Table 3 highlights the values for the target properties and the selection criteria for 6 polymer repeat units and the best polymer is highlighted. 

In line with the terminology adopted, X is commonly called the dopant counter anion and y, which represents the ratio between dopant ion and polymer repeating unit, is commonly called the doping level. 

Fig. 19 Dependence of the brush thickness reduced by the number of polymer repeat units for monovalent co-ions, H/AT, on the concentration of the external salt, ( s> for strong (solid line) and weak (dashed line) polyelectrolyte brushes in neutral brush (NB), salted brush (SB), and osmotic brush (OB) regimes, a and ao denote the bulk and internal (for weak polyelectrolyte brushes only) degree of dissociation, respectively (Reproduced with permission from [89])...

The contrast between formulas 20 and 21, both pertaining to isotactic polyethylidene, should be noted This contrast occurs because the polymer repeating unit has only one carbon atom in the chain and thus there is no correspondence between such periodicity and that of the zigzag representation. The classical definition of an isotactic polymer (as one in which all substituents are on the same side of the chain) holds true, in general terms, only if the polymer is represented in the Fischer projection. Analogous considerations pertain to syndiotactic polyethylidene 22 and 23. 

Dielectric polarization is the polarized condition in a dielectric resulting from an applied AC or DC field. The polarizability is the electric dipole moment per unit volume induced by an applied field or unit effective intensity. The molar polarizability is a measure of the polarizability per molar volume thus it is related to the polarizability of the individual molecules or polymer repeat unit. 

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