2 Light Scattering, a New Technique for Polymers
In 1956, Walther Burchard, a Diploma Physicist, entered the institute and built up the
new light scattering (LS) technique. After 7 months, reliable LS measurements could
be performed. The required molar mass determination of the enzymatically synthesized amylose was possible after full derivatization of the OH-groups with phenyl
isocyanate that led to good solubility in organic solvents. Since amylose and cellulose
differ chemically solely by the type of the glycosidic bond, the derivatized cellulose
was also included in this study. The structural influence of the different glycosidic
links could clearly be demonstrated [1].
3 Branched Polymers
Amylose is present in starch to about 20%, the rest is the highly branched amylopectin. At that time the molar mass and macromolecular size was unknown. The
complexity of branched structures was frightening to most chemists and the study of
amylopectin was avoided. In 1967, Professor Manfred Gordon (Essex University at
Colchester, UK), gave a lecture on the powerful possibilities of branching theory to
calculate the molar mass averages M w and M n , and some important properties on the
elastic modulus of networks formed after gelation in a randomly crosslinking system.
The unperturbed radius of gyration was also calculated. In Colchester in 1969, the
branching theory was extended to static and dynamic light scattering by Kanji
Kajiwara, Walther Burchard, and Manfred Gordon [2]. Two years later, the theory
of AB 2 polycondensates (now better known as “hyperbranched” (hb)-polymers) was
developed [3] and proved to be helpful for interpreting such polymers. At that time
the paper did not attract much interest.
4 Chain Stiffness and Excluded Volume Effects
Chain stiffness and the effects of excluded volume became the dominating issue in
the years between 1980 and the start of the new millennium. Percolation simulations
indicated strong effects on the unperturbed polymer conformations due to excluded
volume interactions [4]. With specially synthesized model substances (prepared by
the Burchard group), the transition from mean-field to highly perturbed conformation
was explored [5–17]. Studies in 1996 [8] on randomly branched, and in 2004 on
hyperbranched polymers [8, 18–20], showed that the fractal conception could be
quantitatively adjusted to the scattering behavior of linear and branched structures
over the whole q-domain and offered valuable insight into the structure in space [16].
152
W. Burchard
In 1956, Walther Burchard, a Diploma Physicist, entered the institute and built up the
new light scattering (LS) technique. After 7 months, reliable LS measurements could
be performed. The required molar mass determination of the enzymatically synthesized amylose was possible after full derivatization of the OH-groups with phenyl
isocyanate that led to good solubility in organic solvents. Since amylose and cellulose
differ chemically solely by the type of the glycosidic bond, the derivatized cellulose
was also included in this study. The structural influence of the different glycosidic
links could clearly be demonstrated [1].
3 Branched Polymers
Amylose is present in starch to about 20%, the rest is the highly branched amylopectin. At that time the molar mass and macromolecular size was unknown. The
complexity of branched structures was frightening to most chemists and the study of
amylopectin was avoided. In 1967, Professor Manfred Gordon (Essex University at
Colchester, UK), gave a lecture on the powerful possibilities of branching theory to
calculate the molar mass averages M w and M n , and some important properties on the
elastic modulus of networks formed after gelation in a randomly crosslinking system.
The unperturbed radius of gyration was also calculated. In Colchester in 1969, the
branching theory was extended to static and dynamic light scattering by Kanji
Kajiwara, Walther Burchard, and Manfred Gordon [2]. Two years later, the theory
of AB 2 polycondensates (now better known as “hyperbranched” (hb)-polymers) was
developed [3] and proved to be helpful for interpreting such polymers. At that time
the paper did not attract much interest.
4 Chain Stiffness and Excluded Volume Effects
Chain stiffness and the effects of excluded volume became the dominating issue in
the years between 1980 and the start of the new millennium. Percolation simulations
indicated strong effects on the unperturbed polymer conformations due to excluded
volume interactions [4]. With specially synthesized model substances (prepared by
the Burchard group), the transition from mean-field to highly perturbed conformation
was explored [5–17]. Studies in 1996 [8] on randomly branched, and in 2004 on
hyperbranched polymers [8, 18–20], showed that the fractal conception could be
quantitatively adjusted to the scattering behavior of linear and branched structures
over the whole q-domain and offered valuable insight into the structure in space [16].
152
W. Burchard