Chain in solution

The second case involves non-adsorbing polymer chains in solution. It was realized by Asakura aird Oosawa (AO) [50] aird separately by Vrij [51] tlrat tlrese chains will give rise to air effective attraction between colloidal particles. This is kirowir as depletion attraction (see figure C2.6.4. We will summarize tire AO tlreory to explain tlris. 

Solvent disturbs chain deflection by interacting with it. At first, solvent molecules must be moved at chain deflection. In this case it may sufficiently decrease the distance between interacting atoms, which are closely disposed and valently disconnected. The model of a homogenous chain in solution is described [12]. The chain in the solvent possesses a higher observable local rigid-... 

Fig. 6. Bead-spring and elastic dumbbell representation of a polymer chain in solution...

This article is not intended to give a comprehensive overview over the entire field, but will concentrate on some recent developments and highlights as perceived by the author. Only most recent references will be given where most of the previous work will be found. There are several books, proceedings and review articles available on earlier work and on specific aspects of polymers at interfaces [1-13]. In particular the area of tethered chains in solution or melt is covered by another article in this book [14]. 

Emulsion polymerisation is initiated using a water-soluble initiator, such as potassium persulfate. This forms free radicals in solution which may initiate some growing chains in solution. These radicals or growing chains pass to the micelles and diffuse into them, which causes the bulk of the polymerisation to occur in these stabilised droplets. 

Noting the influence of temperature on the intrinsic viscosity is given by the parameter of chain flexibility (dln[ j]/d7), which gives information about the conformation of the macromolecule chain in solution (Kasaii 2007, Chen and Tsaih 1998). The chain flexibility parameter in the temperature range of 20-29°C is dln[t]]/dT = 4,404.11K-i, 0.9993 and in... 

Smith, T. A., Hotta, J., Sasaki, K, Masuhara, H. and Itoh, Y. (1999) Photon pressure-induced association of nanometer-sized polymer chains in solution./. Phys. Chem. B, 103,1660-1663. 

A. Malevanets and J. M. Yeomans, Dynamics of short polymer chains in solution, Europkys. Lett. 52, 231 (2000). 

Comparison of solution pH with the pKa of a side chain informs about the protonation state. A unique pKa, termed the standard or model pKa, can be experimentally determined for each ionizable side chain in solution when it is incorporated in a model compound, often a blocked amino acid residue [73] (Table 10-1). In a protein environment, however, the pKa value of an ionizable side chain can substantially deviate from the standard value, due to desolvation effects, hydrogen bonding, charge-charge, charge-dipole, and other electrostatic interactions with the... 

The bundle model of polymer crystallization will be discussed first. This mean-field approach describes the metastable configurational equilibrium of the undercooled polymer chain in solution or in the melt, and we will summarize and update previous work of ours [7-9]. The concept of the bundle, i.e. an aggregate of a few parallel polymer segments or stems connected by folds (see Fig. 1 see also [10]) and stabilized by attractive crystal-like interac-... 

The above considerations apply to isolated polymer chains in solution, i.e. at very low polymer concentrations or volume fractions, < >p (i.e. in the limit < >p - 0). As p increases, interchain interactions becom important. Indeed, at a critical polymer concentration, interchain overlap begins, and beyond a second critical concentration, the chains are so overlapped... 

VC=C n the yellow solution. In both cases the experimental data are quite well represented considering that there is only one parameter in the fit. The model also adequately describes the Raman excitation profile. The good agreement between the model and the experimental results confirms the basic premise of the model that the individual polymer chains in solution contain a distribution of chain lengths which determine the absorption characteristics of the solutions. 

The quenching of benzophenone phosphorescence has been used by Mar and Winnik (1981) as a photochemical probe of hydrocarbon chains in solution. The bimolecular reaction for quenching the triplet state of 4-methoxy-carbonylbenzophenone [24] by 1-pentene occurs at rates which are below the diffusion limit by two to three orders of magnitude. Consequently, the intramolecular quenching reactions of to-alkenyl esters of benzophenone-4-carbo-xylic acid [25] occurs under conformational control. In [25] the point of... 

Early interest in the relation between the shape of chain molecules and solvent in ring-closure reactions can be traced in the work of Salomon (1936a). More recently, the problem has been given much attention by Winnik (1977). Though being small (see p. 64), the corresponding effects on the ease of cyclisation are believed to be of considerable importance in probing the shape of hydrocarbon and other flexible chains in solution. 

Cifra, P. and Bleha, T. Conformer populations and the excluded volume effect in lattice simulations of flexible chains in solutions, Polymer, 34 (1993). 3716-3722... 

Lemak, A. S. and Balabaev, N. K. (1996). Molecular dynamics simulation of a polymer chain in solution by collisional dynamics method, J. Comput. Chem., 17, 1685-1695. 

Mechanistic and theoretical aspects of the reactivity of macromolecular chains in solution... 

C., and Fushman, D. Structural properties of polyubiquitin chains in solution,/ Moi Biol, 2002, 324, 637-47. 

These hosts consist of chains weakly bonded to one another. One example is a series of compounds of Mo and Se, in which cubes of Mo and Se are arranged in chains, and can accommodate guest ions between the chains (Chevrel and Sergent, 1982). In these compounds, it is possible to remove the intercalated ions and separate the chains in solution (Tarascon et al., 1985). 

For small chains in solution the translational diffusion significantly contributes to the overall decay of Schain(Q>0- Therefore precise knowledge of the centre of mass diffusion is essential. Combing dynamic light scattering (DLS) and NSE revealed effective collective diffusion coefficients. Measurements at different concentrations showed that up to a polymer volume fraction of 10% no concentration dependence could be detected. All data are well below the overlap volume fraction of (p =0.23. Since no -dependence was seen, the data may be directly compared with the Zimm prediction [6] for dilute solutions ... 

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