Ph.D. DEFENSE COMMITTEE

Advisor:  Professor Sanjay Rastogi (Chemical Engineering)

Chair:  Professor Nikos Hadjichristidis (Chemistry)

External Committee Member:  Professor Theo Tervoort (ETH Zürich Institut für Polymere)

Internal Committee Member:  Professor Javier Ruiz-Martinez (Chemical Engineering)

Additional Committee Members:  Professor Luigi Cavallo (Chemistry)  and Dr. Ameur Louhichi (KAUST Research Scientist)

Abstract

Polypropylene is a versatile semi-crystalline polymer known for its mechanical, thermal, and chemical properties. The development of ultra-high molecular weight isotactic polypropylene has been challenging due to its high melt viscosity, which complicates traditional processing methods. Recent advancements in catalyst technology and processing techniques have opened new possibilities for producing high-performance UHMWiPP.

This dissertation explores the development of advanced polypropylene materials with exceptional mechanical properties. The purpose of this research is to synthesize UHMWiPP with low entanglement density and high molecular weight, enabling enhanced mechanical properties and processability. The study explores the use of advanced catalyst systems and solvent-free solid-state processing methods to achieve these objectives.

The methods and processes used in this research include the synthesis of UHMWiPP using hafnium-pyridyl amido catalysts activated by trityl tetrakis(pentafluorophenyl) borate. The study investigates the effects of polymerization conditions on molecular weight, tacticity, and entanglement density. Characterization techniques such as hightemperature gel permeation chromatography, rheological analysis, nuclear magnetic resonance, differential scanning calorimetry, scanning electron microscopy, and transmission electron microscopy are employed to analyze the synthesized polymers.