Polyelectrolyte mechanical properties

Modification of the membranes affects the properties. Cross-linking improves mechanical properties and chemical resistivity. Fixed-charge membranes are formed by incorporating polyelectrolytes into polymer solution and cross-linking after the membrane is precipitated (6), or by substituting ionic species onto the polymer chain (eg, sulfonation). Polymer grafting alters surface properties (7). Enzymes are added to react with permeable species (8—11) and reduce fouling (12,13). 

The preparation of molecular composites by electropolymeriza tion of heterocycles in solution with polyelectrolytes is an extremely versatile technique, and many polyelectrolyte systems have been studied. The advantages of this method include the use of aqueous systems for the polymerization. Also, the physical and mechanical properties of the overall composite depend on the properties of the polyelectrolyte, so material tailorabiUty is feasible by selection of a polyelectrolyte with desirable properties. 

Watts, D. C., Combe, E. C. Greener, E. H. (1979). Effect of storage conditions on the mechanical properties of polyelectrolyte cements. Journal of Dental Research, 58, Special Issue C, Abstract No. 18. 

Typically, a binary system was selected as the base component of the recipe and the addition of polyelectrolytes to either side (core or receiving bath) was tested to evaluate the change in the capsule properties. The 33 successful multicomponent membrane systems are presented in Table 1. The components of the core material side (21 different chemical compositions) are listed in the first column, while the receiving bath components (20 different chemical compositions) are listed in the second column. With the exception of xanthan and CMC, the first polymer listed on the core side are gelling polymers which form beads with the appropriate ionotropic cation (salt). CMC can also be gelled by ions (alum), although they are considered to be non-compatible for cellular applications. The cations were tested both sequentially, usually with ionotropic cation first, and simultaneously. Walled capsules with adequate mechanical properties were often obtained through the simultaneous application of two polycations. Such a... 

Modification of the membranes affects the properties, Cross-linking improves mechanical properties and chemical resistivity, Fixed-charge membranes are formed by incorporadng polyelectrolytes into polymer solution and cross-linking after the membrane is precipitated, or by... 

Keywords wrinkling Thin-film Elastomeric polymer Polydimethylsiloxane Patterns Deformation Surfaces Self-assembly Polyelectrolyte multilayer films Thin-films Polymer brushes Colloidal crystallization Mechanical-properties Assembled monolayers Buckling instability Elastomeric polymer Tobacco-mosaic-virus Soft lithography Arrays... 

Picart C, Bernard S, Sengupta K, Dubreuil F, Fery A (2007) Measuring mechanical properties of polyelectrolyte multilayer thin films novel methods based on AFM and optical techniques. Colloids Surf A Physicochem Eng Asp 303 30-36... 

Mechanical Properties of Freestanding Polyelectrolyte Capsules a Quantitative Approach Based on Shell Theory... 

Keywords Polyelectrolytes Multilayers Mechanical properties Deformation Shells Capsules... 

The mechanical properties of polyelectrolyte multilayer capsules have been subject of several studies using different methods. Baumler and co-workers [7] have used the micropipette technique and found that PMCs are not conserving their volume if pressure differences are applied between inside and outside of the shell. This is expected, since the shells can only be formed in first place because the membrane is permeable to low molecular weight species, the core dissolution products. They found no deformation up to a critical pressure followed by an irreversible collapse, showing that shells deform not elastically but plastically for large deformations. First quantitative estimates of the Young s modulus of the shell material were obtained by Gao and coworkers, using osmotic pressure differences between inside and outside of the shell [8,9], These authors monitored the onset of the buck-... 

Kig. 21. Mechanical properties of the polyelectrolyte complex of poly(sodium styrenesulfonate) (NaSS)-poly(4-vinylbenzyl-trimethylammonium chloride) (PVBMA)S4). (1) modulus, (2) elongation, (3) tensile strength... 

Mechanical properties of the chemically modified wood depend on the nature of the introduced side chain. If the introduced side chain is ionized, the interaction between wood component molecules is influenced by not only the free volume but also by electrostatic repulsion of ionized side chains. For example, the conformation of polyelectrolyte depends on the degree of ionization [23-28]. The structure is transformed from random coil to rod-like conformation with an increase in the degree of ionization. A screening effect also influences the interaction because electrostatic action is inhibited by electrolytes such as NaCl. 

The physical properties of ICPs can also be manipulated by incorporating polyelectrolytes (PEs) as dopants. For example, sulfated polyO-hydroxy ethers) have been incorporated with dramatic effects on the mechanical properties -increasing the stretchability to greater than 200% [147,148]. Others [149] have shown that polyanilines can be rendered water soluble by incorporation of appropriate polyelectrolytes such as polystyrenesulfonate. Electrically conducting gels (materials with high water content/good conductivity) are also formed by incorporation of polyelectrolytes as dopants [150,151]. 

A.S. Michaels and R.G. Miekka, Polycation-polyanion complexes Preparation and properties of poly(vinylbenzyltrimethylammonium) and poly(styrenesulfonate), J. Phys. Chem., 1961, 65, 1765-1773 A.S. Michaels, L. Mir and N.S. Schneider, A conductometric study of polyaction-polyanion reactions in dilute solution, J. Phys. Chem., 1965, 69, 1447-1455 S.J. Reid, J. Th. Overbeek, W. Vieth and S.M. Fleming, Membrane potential differences with the polyelectrolyte complex - poly(vinyltrimethy-lammonium)-poly(styrenesulfonate), J. Colloid Polym. Sci., 1968, 26, 222-229, O. Yano and Y. Wada, Effect of sorbed water on dielectric and mechanical properties nf nnlvinn enmnlex../ Ann Polvm. Sci.. 1980. 25. 1723-1735. 

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