The effect a Co(II) based catalytic chain transfer agent (CCTA) has on the course of the polymerization and the product properties of an emulsion polymerization is governed by the intrinsic activity and the partitioning behavior of the catalyst. The effect on the conversion time history, the molecular weight distribution and the particle size distribution is evaluated in batch emulsion polymerization of methyl methacrylate for three different CCTAs, which cover a range of intrinsic activities and partitioning behaviors. It was demonstrated that radical desorption from the particle phase to the aqueous phase preceded by chain transfer is the main kinetic event controlling the course of the polymerization and the product properties in terms of the particle size distribution. The experimental results show that the aqueous phase solubility of the CCTA is the key parameter controlling the course of the polymerization and the particle size distribution.

An alternative mass transport mechanism, based on collisions between different entities, is used to explain the performance of an extremely hydrophobic catalytic chain transfer agent (i.e. COPhBF) in emulsion polymerization. Mass transport in emulsion polymerization is generally accepted to proceed via the aqueous phase. COPhBF possesses no detectable water-solubility and would therefore be expected to be inefficient for molecular weight control in emulsion polymerization. However, proper molecular weight control using COPhBF has been demonstrated and results are presented that are consistent with the existence of an alternative mass transport mechanism in emulsion polymerization that circumvents the aqueous phase.

Summary: For the application of catalytic chain transfer in (mini)emulsion polymerization, catalyst partitioning and deactivation are key parameters that govern the actual catalyst concentration at the locus of polymerization and consequently the final molecular weight distribution. A global model, based on the Mayo equation, catalyst partitioning and deactivation was developed. The influence of several reaction parameters on the instantaneous number average molecular weight was quantified.

A novel synthetic pathway towards aldehyde end-functionalized polymers is presented from a combination of catalytic chain transfer polymerization (CCTP) and rhodium catalyzed hydroformylation in supercritical carbon dioxide. CCTP allows for the synthesis of well-defined macromonomers in terms of the average molecular weight and the terminal unit carrying the unsaturated bond. The rhodium catalyzed hydroformylation allows for a high selectivity towards aldehyde end-group functionalized polymers. The introduction of the synthetically versatile aldehyde end-group opens up a broad range of possible applications.

Carbon nanotubes were introduced into insulating polystyrene (PS) and poly(methyl methacrylate) (PMMA) by means of a latex-based technique. A systematic study of the effect of the polydispersity index, more particularly the presence of different amounts of low molar mass polymer, on the final composite conductivity was performed. Six latexes with varying molecular weight distributions were prepared by means of conventional free radical emulsion polymerization in the presence of different amounts of chain transfer agent, namely n-dodecyl mercaptan. Composites were prepared with both multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). Shifts in the percolation threshold from 0.9 to 0.6 wt% for MWCNTs and from 0.7 to 0.4 wt% for SWCNTs were observed for PS matrix material, whereas for PMMA matrix material the percolation thresholds shifted from 0.6 to 0.3 wt% for MWCNTs and 0.35 to 0.2 wt% for SWCNTs upon increasing the amount of low molecular weight polymer in the polymer matrix.