Polymer chemistry is that branch of one, which deals with the study of synthesis and properties of macromolecules. Polymers are formed by polymerization of monomers. A polymer is chemically described by its degree of polymerisation, molar mass distribution, tacticity, copolymer distribution, the degree of branching, by its end-groups, crosslinks, crystallinity and thermal properties such as its glass transition temperature and melting temperature. Polymers in solution have special characteristics with respect to solubility, viscosity and gelation. The work of Henri Braconnot in 1777 and the work of Christian Schnbein in 1846 led to the discovery of nitrocellulose, which, when treated with camphor produced celluloid. Polymer chemistry touches many scientific disciplines and is vital in fields that develop products such as plastics and synthetic fibres; agricultural chemicals; paints and adhesives; and biomedical applications such as artificial skin, prosthetics, and the nicotine patch that helps smokers overcome their smoking habit. It is estimated that as many as 50% of all chemists will work in polymer science in some capacity during their careers. 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.