Polymers colloidal particles

Fig. 4. Schematic of polymer colloidal particles stabilized by PFOA homopolymer [103]...

Another generator that was successfully used in the formation of polymer colloids, particles of mixed composition, and coated particles is shown in Figure 1.5.3f, in which the falling film tube is replaced by a boiler (38). The complete apparatus described in Figure 1.5.3 makes it possible to produce cores and shells in a continuous process (39). 

Spontaneous formation of nanoparticles can be achieved by taking advantage of the solubility and gelling properties of a dissolved polymer. Usually, the step allowing polymer colloidal particles to form is reversible, and it is necessary to complete the procedure by a second step required to stabilize the particles. 

The pore shape influences the mass transfer rate and thus the efficiency of separation. The effective diameter of pores determines the range of separated molar masses. The pore size distribution and the pore volume are decisive for selectivity of separation (section 4.6.2.3). The pore sizes of commercially available gels cover the region necessary for separation of the wide spectrum of substances — from low molecular samples to very high polymers, colloidal particles and viruses. The mean values of pore diameters range from few nanometers to about 2.5 /xm. Gels with various pore sizes, but of the same type, can be combined within the same column. 

A polymer colloid particle will typically contain a substantial number of polymer chains within the particle. These can be arranged in a crystalline, amorphous, rubbery or glassy state. Monomer can also be retained by the particles and hence the particles can be, where the polymer is soluble in the monomer, either extensively or minutely swollen. The physical state of the particle can be important in close-range colloidal and hydrodynamic interactions and in drying processes. For example, if the particles are soft, coalescence of the particles can occur to give continuous film formation, whereas with hard particles their individuality is retained in the dry state. 

The surface potential, yj/t, which we introduced above is essentially a model potential, and although estimates of this can be obtained from experiments such as interaction between mica hemicylinders these are rather sophisticated experiments and not readily available on a day-to-day laboratoiy- basis. However, electrokinetic experiments, particularly electrophoresis, can often be carried out quite readily even with simple equipment. For example, measurement of the electrophoretic mobility, u, of a spherical polymer colloid particle in a medium of... 

In the high relative permittivity, r, of water most polymer colloid particles carry an electric charge. Frequently, depending on the synthetic method used to prepare the particles this arises from ionizable groups on the surface, such as... 

The nomenclature Vr for this quantity is that normally adopted in the literature of colloidal dispersions, and as a time-average scalar quantity it is very useful for discussing the stability of colloidal dispersions, foam films, wetting films, etc. [19-21]. Since this article is primarily concerned with polymer colloid particles the arguments will be confined to irueractions between spheres, and expressed in terms of the particle radius, R, and either the distance of surface-to-surface separation, h, or the centre-tcxentre distance between the particles, r. 

In the formation of polymer colloid particles in the size region of 1 pm, de-wetting of the particles can also occur as the monomer is used up and the surface tension of the aqueous phase rises adsorption of the particles at the air-water interface in this case can lead to a particle-stabilized foam. Particles of this sort can also be spread on a Langmuir trough and will form a hexagonally close-packed monolayer [76]. 

As shown earlier in Section 3.3.1, the presence of charged groups on the surface of a polymer colloid particle provides a powerful method of producing... 

Ottewill RH, Schofield AB, Waters JA, Williams NSJ (1997) Preparation of core-shell polymer colloid particles by encapsirlation. Colloid Polym Sd 275 274-283 Okubo M, Lu Y, Wang Z (1999) Analysis of stepwise heterocoagulation for the preparation of soft core/hard shell composite polymer particles. Colloid Polym Sd 277 77-82 Xu Y, Brittain WJ, Xue C, Eby RK (2004) Effect of clay type on morphology and thermal stability of PMMA-clay nanocomposites prepared by heterocoagulation method. Polymer 45(ll) 3735-3746... 

Fitch, R.M. and Tsai, C.H. (1970) Polymer colloids - particle formation in nonmicellar systems. J. Polym. Sci. Part B Polym. Lett., 8, 703. 

More recently, DPN techniques have been extended and developed to pattern a variety of ink-substrate combinations. DPN has been shown to be compatible with a wide array of ink types including small organic molecules, organic and biological polymers, colloidal particles, metal... 

Figure 3.42. The relative proportion.s of silica present as monomer, oligomer, and high polymer (colloidal particle.s) as a 400 ppm solution of SilOllh polymerizes at 30°C at pH. V yt, monomer B, oligomer C high polymer" or colloidal particles D, reciprocal of the reaction velocity constant, k, of oligomer with molybdic acid. [From VVcitz. Franck, and Ciller (MS).]...

The Theoretical Basis of Latex Stabiiization. The colloidal stabihty of each class of latex is primarily dependent on the effectiveness of the sindactant. In the high permittivity of water, most polymer colloid particles carry an electric... 

Miscellaneous Forces. Force measurements on polymer surfaces or between chemically modified SFM tips and polymer surfaces yielded important insight into fundamental force vs separation distance relationships for, eg, polymer colloidal particles (207), mechanochemical behavior of individual macromolecules (see section Entropic and Enthalpic Elasticity) (87-96,99), but also adhesion information directly relevant for practical applications, such as electrochemically controlled adhesion (208) or toner particle-rubber interactions relevant for xerographic applications (209,210). 

Non-convertible aqueous coatings are typieally a latex emulsion consisting of colloidal polymer particles, usually smaller than 0.5 microns, which are stabilized with an emulsifier to prevent flocculation and coalescence. As illustrated in Figure 1, once a latex paint is applied, water begins to evaporate and the polymer colloidal particles become increasingly concentrated. The particles eventually touch and pack together, leaving voids filled with water which must eventually be lost to evaporation or porous absorption of the substrate. Finally the particles completely coalesce and fuse into a continous fdm. 

Ordered Array Structure of Polymer Colloidal Particles on a Patterned Substrate. 174... 

Figure 26 illustrates the set-up and schematic procedures of the tapered cell method [140, 141], where a cover glass was slightly tilted (angle = 1-2°) on the patterned Si substrate. An aqueous dispersion liquid of polymer colloidal particles... 

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