Area per grafted chain

Table III. Average Substrate Surface Area Per Graft Chain, A2 X 10 3...

Fig. 17 Dependence of the average PEO brush height ((Jj)brush) on the surface area per grafted chain (s), where (/i)brush was calculated by two different methods. The squares represent (h)brush from the difference between the average radii of the PNIPAM microgels with and without the grafted PEO chains and the circles from the ratio of / [70]...

Impact strength of ABS graft resins will increase with increasing particle size of the substrate latex when the substrate surface area per grafted copolymer chain is maintained at equivalent values. At 20 wt % substrate levels the increase in impact strength appears linear with increasing particle size, but at 30 wt % substrate, nonlinearity is indicated wjien the substrate particle is less than 1100 A. The inverse relationship of tensile and impact strength is preserved. 

Monomer compositional drifts may also occur due to preferential solution of the styrene in the mbber phase or solution of the acrylonitrile in the aqueous phase (72). In emulsion systems, mbber particle size may also influence graft stmcture so that the number of graft chains per unit of mbber particle surface area tends to remain constant (73). Factors affecting the distribution (eg, core-sheU vs "wart-like" morphologies) of the grafted copolymer on the mbber particle surface have been studied in emulsion systems (74). Effects due to preferential solvation of the initiator by the polybutadiene have been described (75,76). 

FIG. 15 Free energy per unit area as a function of surface separation for five different values of x-The parameters are Ng = 25, p = 0.04, N = 100, and Xsurf = 0. The cartoon on the left shows the reference state, where the grafted chains form a melt between the surfaces. In the cartoon on the right, the surfaces are separated by polymers that have localized between the interfaces. (From Ref. 100.)... 

The surface area per sterically-stabilized particle is determined by the surface area (S) occupied by a macromonomer chain times the number (n ) of these chains grafted onto the surface. 

Important parameters that control the size of micelles are the degree of polymerization of the polymer blocks, NA and NB, and the Flory-Huggins interaction parameter %. The micellar structure is characterized by the core radius Rc, the overall radius Rm, and the distance b between adjacent blocks at the core/shell-interface as shown in Fig. 1. b is often called grafting distance for comparisons to polymer brush models, b2 is the area per chain which compares to the area per head group in case of surfactant micelles. In the case of spherical micelles, the core radius Rc and the area per chain b2 are directly related to the number of polymers per micelles, i.e., the aggregation number Z=4nR2clb2. 

A DEA group was appended onto a polyethylene porous hollow-fiber membrane with a density of 2.2 mmol per gram of the resultant DEA-EA fiber. The inner and outer diameters of the hollow fiber were 2.4 and 4.4 mm, respectively. The liquid permeability, i.e., the permeation rate per unit of inside surface area, of the DEAEA fiber for the buffer was maintained at 50% of that of the original hollow fiber. Volume swelling of the porous hollow fiber accompanied by graft polymerization prevented the graft chains from filling the pores. 

A sketch of a polymer brush is shown in Fig. 1. We call a the graft density or the number of grafted chains per unit area of the surface. Each chain has N monomers. In a dilute solution the chain radius of gyration, R, is for Gaussian chains in a 0 solvent... 

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