ISSN:
1434-6036
Keywords:
PACS. 61.41.+e Polymers, elastomers, and plastics[:AND:] 87.15.-v Molecular biophysics - 64.70.-p Specific phase transitions
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract: We study a single self avoiding hydrophilic hydrophobic polymer chain, through Monte-Carlo lattice simulations. The affinity of monomer i for water is characterized by a (scalar) charge , and the monomer-water interaction is short-ranged. Assuming incompressibility yields an effective short ranged interaction between monomer pairs (i,j), proportional to . In this article, we take (resp. ( )) for hydrophilic (resp. hydrophobic) monomers and consider a chain with (i) an equal number of hydro-philic and -phobic monomers (ii) a periodic distribution of the along the chain, with periodicity 2p. The simulations are done for various chain lengths N, in d=2 (square lattice) and d=3 (cubic lattice). There is a critical value p c (d,N) of the periodicity, which distinguishes between different low temperature structures. For p 〉p c , the ground state corresponds to a macroscopic phase separation between a dense hydrophobic core and hydrophilic loops. For p 〈p c (but not too small), one gets a microscopic (finite scale) phase separation, and the ground state corresponds to a chain or network of hydrophobic droplets, coated by hydrophilic monomers. We restrict our study to two extreme cases, and to illustrate the physics of the various phase transitions. A tentative variational approach is also presented.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s100510050531
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