Well-founded scientific knowledge from two areas played a key role in the development of Styrolux and Styroflex: this knowledge relates firstly to sequential, anionic polymerization, and secondly to the fundamental structure-property relationships between the molecular architecture, morphology and mechanics of polymers. Skills in both fields are combined to deliver innovative solutions: when the complex structure-property relationships are known, the great architectural variability of the block copolymers can be utilized to customize to any desired application.

Sequential, anionic polymerization opens up a variety of approaches to designing molecular architecture: this is influenced by the method of initiation, the type and quantity of monomers, the chosen solvent, the temperature, the sequence of polymerization steps and the method of stopping the reaction.

 
Knowledge of structure-property relationships at several levels is necessary to optimize synthetic polymers:

• Structure-property relationship between the molecular structure (chemical synthesis) and the morphology of the resulting block copolymers (physical separation processes).
  
• Structure-property relationship between the morphology of the block copolymers and their macroscopic properties such as toughness, rigidity, hardness, transparency, softening temperature, as well as permeation and surface properties.
  
• Structure-property relationships between the chemistry of the basic components and the macroscopic properties.

The scales of magnitude involved here are remarkable: from the microscopic (molecule of several pm) through the mesoscopic (domains about 10 nm) to the macroscopic scale (test specimen about 10 cm). One of the methods used to study the morphology of polymers is transmission electron microscopy. The resulting macroscopic properties can then be linked to the molecular architecture and the morphology. After the individual polymerization steps, the architecture can be studied by GPC. With styrene-butadiene copolymers, not only the architecture but also the microstructure of the butadiene units is important and can be determined by NMR analysis.

The demand for impact-resistant thermoplastics which are simultaneously transparent cannot be met using the conventional methods of radical polymerization. Only by developing sequential, anionic polymerization of styrene and butadiene into a commercial process could these materials be obtained.

The researchers wanted to satisfy completely different requirements when developing Styroflex: the plastic they were looking for was to be a thermoplastic elastomer suitable for use as a thin film in food packaging and as a material in the toy sector.
As with Styrolux, the scientists again used styrene and butadiene as the basic components, and the technology they used was again anionic polymerization. The desired properties were finally obtained by distributing part of the styrene statistically throughout the rubber elastic butadiene block which was thereby enlarged.