Date of Award

12-2006

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

Jimmy W. Mays

Committee Members

Mark Dadmun, John Turner, Roberto Benson

Abstract

Anionic polymerization based upon high vacuum technique has been used to synthesize different star polymers using varying linking techniques. In particular chlorosilanes, divinylbenzene, and polyhedral oligomeric silsesquioxane (POSS) chlorosilane derivatives were used in the synthesis of star polymers. These polymers, along with polymers synthesized by others, have been characterized by a range of methods in this work.

A series of polyisoprene (PI) stars were synthesized from dimethylaminopropyllithium (DMAPLi) and subsequently hydrogenated to form poly (ethylene-co-propylene) (PEP) these were characterized by size exclusion chromatography (SEC) coupled with online two angle laser light scattering (TALLS). These polymers were synthesized in an attempt to make a new series of viscosity index improvers as an oil additive. The polymers were characterized by differential scanning calorimetry and thermal gravimetric analysis.

A novel process for producing eight arm star polymers was explored using a Polyhedral Oligomeric Silsesquioxane (POSS) modified with chlorosilanes as the linking agent. The arms of these stars were prepared polybutadiene prepared anionically. A study of the effect of living end-groups was also explored by endcapping the living polybutadiene with a polystrylanion and the linking efficiency was monitored. These polymers were also characterized by SEC coupled with TALLS.

A series of polystyrene (PS) combs and centipedes were used to gather information about the intrinsic viscosity ([η]), radius of gyration (Rg), and hydrodynamic volume as compared to linear PS polymers of a comparable molecular weight. These values were examined under good solvent and theta solvent conditions. The g’ and g parameters were examined for comb and centipede type polymer architectures and compared to literature values. The validity of a new theory SEC separation was explored using the hydrodynamic volume to explain the primary means of separation in SEC columns.

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