Polymer particle assembly

Fluid motion can also be controlled by chemically patterned templates which modulate the wetting of the surface [51]. Liquid is pinned in a manner similar to that occurring in topographical templates, although the effect is less pronounced and can be easily disturbed by self-pinning of the particle suspension due to unspedfic deposition [52], A general limitation of this kinetic approach is the systematic influence of the direction that the particle suspension is moved across the surface, an effect more pronounced on chemical than on topographical templates. 

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E. Wolert, S. M. Setz, R. S. Underhill, R. S. Duran, M. Schappacher, A. Deffieux, M. Holderle, and R. Mulhaupt, Meso- and microscopic behaviour of spherical polymer particles assembling at the air-water interface, Langmuir 17, 5671-5677 (2001). 

As mentioned earlier, the contact-mechanics-based experimental studies of interfacial adhesion primarily include (1) direct measurements of surface and interfacial energies of polymers and self-assembled monolayers (2) quantitative studies on the role of interfacial coupling agents in the adhesion of elastomers (3) adhesion of microparticles on surfaces and (4) adhesion of viscoelastic polymer particles. In these studies, a variety of experimental tools have been employed by different researchers. Each one of these tools offers certain advantages over the others. These experimental studies are reviewed in Section 4. 

Mono- and Multilayers of Spherical Polymer Particles Prepared by Langmuir-Blodgett and Self-Assembly Techniques... 

Synthesis of polymeric capsules involves polymer self-assembly on many levels and length scales. Approaches to their synthesis include cases where monomers are polymerized around a liquid template, premade polymers are assembled around liquid and solid templates, premade particles are assembled around templates, and small molecules or polymers assemble spontaneously. Each method offers unique challenges and advantages, and each allows the production of capsules with different properties. 

Several major barriers need to be overcome for the development of nonviral gene delivery systems into true therapeutic products for use in humans. These barriers fall into three classes manufacturing, formulation, and stability (extracellular barriers and intracellular barriers) (85). Cationic lipids and cationic polymers self-assemble with DNA to form small particles that are suitable for cellular uptake. At the therapeutic doses positively charged particles readily aggregate as their concentration increases, and are quickly precipitated above their critical flocculation concentration. 

Compartmentalization of radicals into polymer particles may yield a unique MWD for the linear chains, as discussed in Sect. 3.1, except when the dominant chain termination mode is the chain transfer reaction. Branched polymer molecules are assemblies of linear polymer chains (called primary chains), and compartmentalization effects on the primary chain length distribution must be properly accounted for. 

One promising approach that may help to establish APS as the fraction of HMW DOM that assembles into particulate matter is to compare the chemical composition of polymer gel assemblies with HMW DOM. In one such experiment, HMW DOM recovered by ultrafiltration of seawater or spent culture media was redissolved in seawater and agitated by bubbling to produce particles which collect at the top of a bubble tower (Gogou and Repeta, unpublished). Particles formed by bubbling have the same neutral sugars in approximately the same proportions as APS. NMR data likewise show particles to be rich in carbohydrate and have the same major resonances as APS, although the relative amount of major biochemicals differs between the two samples. This and other similar approaches further support the hypothesis that APS is the reactive fraction of... 

Zheng, H. P. Rubner, M. F. Hammond, P. T. Particle Assembly on Patterned Plus/Minus Polyelectrolyte Surfaces Via Polymer-on-Polymer Stamping. Langmuir 2002, 18, 4505—4510... 

Since the latter possibility is only given in case of porous surfaces, dispersion adhesives are mainly used for materials that are capable of binding the water of the liquid adhesive layer by absorption . The remaining polymer particles with their inherent tack fuse to an adhesive layer (film formation). The open assembly time (Section 5.2) in the processing of dispersion adhesives is strongly influenced by the moisture content of the adherends and the relative humidity. The open assembly time increases with higher humidity. 

For example, a novel, versatile technique for the synthesizing of uniform hollow capsules from a broad range of materials is based on a combination of colloidal templating and self-assembly processes [11.8]. Fig. 11.11 describes schematically the concept. Colloidal templates of different composition, size, and geometry (although spheroidal shape is preferred) can be employed. Materials range from spherical polymer particles to non-spherical biocolloids, all vdth diameters in the nano to micrometer range. The... 

For the calculations of the optical properties of polymer films with embedded nanoparticles, two routes can be selected. In the exact route, the extinction cross sections Cact(v) of single particles are calculated. The calculated extinction spectra for single particles—or, better, a summation of various excitation spectra for a particle assembly—can be compared with the experimental spectra of the embedded nanoparticles. In the statistic route, an effective dielectric function e(v) is calculated from the dielectric function of the metal e(T) and of the polymer material po(v) by using a mixing formula, the so-called effective medium theory. The optical extinction spectra calculated from the effective dielectric functions by using the Fresnel formulas can be compared with the experimental spectra. 

Li et al. [51] prepared monodisperse microspheres by distillation precipitation polymerization of DVB and NIPAM with 2,2-azobisisobutyronitrile (AIBN) as initiator in acetonitrile, in the absence of any surfactant. Next, latex particles of poly(EGDMA-co-AA) were assembled onto the microspheres to afford a corecorona composite polymer particle with a raspberry-like morphology, strengthened by hydrogen-bonding interaction. 

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