Homopolymer random walks

Polyethylene is a man-made homopolymer. Its chemical synthesis is well understood. It is a random walk polymer with little secondary or tertiary structure. A batch can largely be characterised by its molecular weight distribution, and its rheology can be related to these parameters by developed rules of polymer behaviour. The action of specific chemicals as plasticisers can be used to modulate these bulk properties in a predictable way, allowing the nature and characterisation of its glass to fluid transition to be predicted. 

Helfand E (1975) Theory of inhomogeneous polymers fundamentals of the Gaussian random-walk model. J Chem Phys 62 999-1005 Hildebrand JH (1936) The solubility of non-electrolytes. Reinhold, New York Hoy KL (1985) Tables of solubility parameters. Union Carbide Corporation, Solvent and Coatings Materials Research and Development Department, South Charleston Hu WB (1998) Structural transformation in the collapse transition of the single flexible homopolymer model. J Chem Phys 109 3686-3690... 

A comparison has been made of the simulation of AB block copolymers as self-avoiding walks on lattices and as random walks with a mean field expression of block incompatibility. In contrast to the case with di-blocks, the A part of BAB tri-blocks is appreciably more expanded than the homopolymer, thus reducing the possibility that in poor solvent the B parts might coalesce to form a ring. ... 

In a melt of homopolymers, the excluded volume interaction is effectively screened. There is no tendency for a chain to swell beyond the ideal random-walk dimension. Only the prefactor, or more precisely the persistence length, is governed by the very local monomer-monomer interactions. The mean-square end-to-end distance of a chain of length N has the form... 

The basic features of folding can be understood in tenns of two fundamental equilibrium temperatures that detennine tire phases of tire system [7]. At sufficiently high temperatures (JcT greater tlian all tire attractive interactions) tire shape of tire polypeptide chain can be described as a random coil and hence its behaviour is tire same as a self-avoiding walk. As tire temperature is lowered one expects a transition at7 = Tq to a compact phase. This transition is very much in tire spirit of tire collapse transition familiar in tire theory of homopolymers [10]. The number of compact... 

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