Adsorption copolymer

However, the surface coverage is the same for both copolymers when weakly adsorbed to the surface. Surface density profiles were also compared. Finally, scaling relationships for triblock copolymer adsorption under weak adsorption conditions were derived (Haliloglu et al. 1997). In a related paper (Nguyen-Misra et al. 1996), adsorption and bridging of triblock copolymers in an athermal solvent and confined between two parallel flat surfaces were studied, and the dynamic response of the system to sinusoidal and step shear was examined. 

The adsorption of block copolymers can be controlled by different stimuli, in particular by the pH since most of the brushes formed by block copolymers adsorption are polyelectrolyte brushes [129, 130], The group of Armes, for instance, studied the pH-controlled adsorption of a series of block copolymers [131, 132], In the case of copolymers bearing hydrophobic 2-(diethylamino)ethyl methacrylate groups (DEA) and a water-soluble zwiterionic poly(2-methacryloyl phosphoryl-choline) (MPC) block, they showed that at low pH the cationic DEA flatted to the anionic silicon surface while the MPC was in contact with the solution [132], At around neutral pH, micelles were formed in solution and adsorbed onto the surface because the DEA core was still weakly cationic. The MPC block formed the micelle coronas. Nevertheless, at higher pH the micelles became less cationic and the adsorption rate decreased. 

The adsorption of block and graft copolymers is more complex, as the intimate structure of the chain will determine the extent of adsorption [37]. Random copolymers adsorb in an intermediate fashion compared to that of the corresponding homopolymers. Block copolymers retain the adsorption preference of the individual blocks. The hydrophilic block (e.g., PEO the buoy) extends away from the particle surface into the bulk solution, while the hydrophobic anchor block (e.g., PS or PPO) provides a firm attachment to the surface. Figure 6.14 shows the theoretical prediction of diblock copolymer adsorption according to SF theory. In this case, the surface density cr was plotted versus the fraction of anchor segments v, and adsorption was shown to depend on the anchor/buoy composition. 

Entrapment in polyacrylamide gel over a platinum grid matrix Glutaraldehyde-mediated reaction with a nylon-polyethyleneimine copolymer Reaction with macroporous aminated silo chrome coated with an acrolein-vinylpyridine copolymer Adsorption onto tannin coupled to amino hex y 1-cellulo se Entrapment in cellulose fibres Carbodi-imide-mediated reaction with chitosan... 

Tiberg, F., Malmsten, M., Linse, P. and Lindman, B., Kinetic and equilibrium aspects of block copolymer adsorption, Langmuir, 1, 2723-2730 (1991). 

We will now consider the three problems referred to above. Random copolymer adsorption refers to the situation in which a copolymer (most simply described as one with two types of monomer, say A and B) is adsorbed onto a surface. Consider an n-step SAW, with a proportion p of A type monomers, and a proportion 1 — p of B type monomers in a half-space. In two dimensions we are therefore referring to that section of 1 with y > 0. Let the origin of the SAW he in the line y = 0. Finally, the energy comes from the A monomers in the line y = 0. That is to say, only the A monomers are attracted to the surface. There is no surface interaction with B monomers. For those SAW, with cardinality c vA a) with va vertices in y = 0, and monomer distribution as described above given by a, where = 1 if the vertex is A and zero otherwise, the partition function is given by... 

For the most relevant case of strong localization, the kinetics of copolymer adsorption is of particular importance. A simple analytical theory based on scaling considerations has been proposed and shown to provide a faithful description for the relaxation of the initial copolymer coil into a flat-shaped layer [45]. This conformational change of a chain for/ > x can be considered to be governed... 

Using these models, we isolated factors that control pattern formation in homopolymers tethered to two surfaces, copolymer-coated surfaces and copolymer adsorption onto pinned micelles. Below, we describe each of these systems separately. 

Copolymer adsorption is more complex as the intimate structure of the chain determines the extent of adsorption. Random copolymers adsorb in an intermediate way to that of... 

Tiberg F, Malmsten M, Linse P, Lindman B. Kinetic and equUibrium aspects of block copolymer adsorption. Langmuir 1991 7 2723-2730. 

Coadsorption Effects on Overall Graft Copolymer Adsorption. Coadsorption effects were explored by varying the sequence of polymer types exposed to the surface, as well as by mixing the polymer types, and then observing the dependence... 

Li, W., et al.. Preparation and characterization of bimodal porous carbons derived from a styrene-divinylbenzene copolymer. Adsorption, 3(1), 67-80 (1997). 

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