The effect of complexation on miktoarm star polymers

Star polymers are polymers in which multiple linear chains emerge from one common point to form the arms of the star polymer. The properties of the star can be tuned by the number of arms and the arm length. Understanding and predicting the properties of such star polymers is the goal of this work. From the great variety of star polymers, we will focus on polymers which form complexes. Complexation in polymers can occur whenever two different types of polymers attract each other. If the attraction is strong enough, the polymers come close to each other to form a complex. We investigated star polymers in which the two polymer types which attract each other are located in different arms of one star polymer. The architecture of such heteroarm star-shaped block copolymers is called miktoarm star polymer.To study and predict the properties of these polymers, Monte Carlo simulations are used as they are a powerful tool to understand and predict the properties of the modeled systems. The model employed in this work is a coarse-grained model which does not capture the chemical details but rather gives a generic insight into the static properties of the complex forming star polymers. By varying parameters of the model used in these simulations, we obtain a detailed view of the effect of these parameters on the properties of the polymers. The computational effort used in these simulations depends on the efficiency of the simulations, which in turn depends on the parameters used in the Monte Carlo algorithm. To increase the efficiency of our simulations, we developed a novel algorithm which optimizes the simulations on the fly and with little computational overhead. This allows us to use the limited computational time available in a better manner and therefore gain better insights into the subject. Studying the effect of the polymer topology (number of arms in the star polymer) and the composition (length of the arms), we were able to show how the intramolecular complexation depends on these factors and how they affect the resulting structure of the formed complex. Comparing these results from the simulations with experimental results show a qualitative agreement, supporting the validity of our model. As the complexation can hinder some desired polymer properties, we looked at an approach to prevent the complexation. By adding a polymer spacer to the system which spatially separates the complex forming polymers, we propose a way of preventing the complexation. We demonstrate the requirements for the polymeric spacer and the resulting structures. Finally, we investigate the aggregation behavior of the complex forming polymers, and show that the polymers are stable toward aggregation, even at high concentrations