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  Institut Theorie der Polymere
  Control of Nanostructure and Morphology

Molecular modelling

• ab-initio calculations of monomer units by application of the software package GAMESS

• Building of linear, hyperbranched and dendritic polymer structures (see below)

• Modelling of molecular crystal structurs as a qualified starting point for RIETVELD Refinement calculations

• RIETVELD Refinement of X-ray powder diffractograms my means of software package BGMN, which includes an own interpreter for a chain model and a force field model (examples are given below: structure investigations of cyclo-tris(2,6-pyridyl) formamidine or high aromatic side chain modified polyesters)

Theoretical aspects of the phase separation and morphology of multi phase block copolymer systems

• Calculation of interaction parameters

• Calculation of phase diagrams by means of mean field approach with respect to the block wise adjustable semiflexibility and/or polydispersity

Molecular modelling, structure investigations and phase separation calculations are performed at a PC cluster (4 double processor PCs and 1 single processor PC) with Linux as operating system including an actual system kernel, where the jobs distributions are performed by means of the OpenPBS batch system. Different software for development and installation of own and foreign software packages (public domain) are available  for compilation, testing and application:

• The C programming language strictly applying the ISO 9899-1990 standard
• MPICH as a powerfull tool for developing parallelized software
• make, gnuplot, Latex, povray, further different shell script languages  and tools from the pool of the current Linux distribution

where stability and velocity are playing an important role to me, more than functionality.

Crystal structures and diffraction patterns:

Cyclic formamidine

Ref.: Friedel, P. et. al., J. Appl. Cryst. (1998) 31, 874-880

 
High aromatic main chain polyester

 Ref.: Jehnichen, D. et. al., Polymer (1998) 39, 1095-1102

Side chain modified polyester

Ref.: Friedel, P. et. al., J. Polym. Sci: Polym. Phys. (2000) 38, 1617-1625

Phase separation of block copolymers:

(Above the lines: area of phase separated block copolymer
Below the lines: area of homogeneous block copolymers)

Influence of blocking degree n in (A-B)_n

Ref.: Benoit, H. et.al. Macromolecules (1988) 21, 1449

Influence of the semiflexibility of diblock copolymers

(Persitent length and monomer length individual abjustable for every block)

Ref.: Friedel, P. et. al. Macromol. Theory Simul. (2003) 11, 785-793

Influence of the polydispersity of the diblock copolymer

(individual adjustable applying the delta-, poisson-, Schultz-Zimm- and/or exponential probability distribution)

Ref.: John, A. et. al. Macromol. Theory Simul. (2004) 13, 702-710

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