Principles of Polymer Chemistry, Second Edition was written for advanced undergraduate and graduate students in polymer chemistry, along with practicing chemists who need a reference guide. Many important events have taken place since the First Edition was published in 1995, and they are updated here. For example, sections have been included on controlled/living free radical polymerization, and sections on metathesis type polymerization and metallocene catalysts were expanded. The book was also expanded to include discussions of thermodynamics of elasticity, thermodynamics of polymeric solutions, and rheology and viscoelasticity. A chapter on degradation of polymers was also added.