Synthesis, Characterization, and Theory of Polymeric Networks and Gels

Polymer science is a technology-driven science. More often than not, technological breakthroughs opened the gates to rapid fundamental and theoretical advances, dramatically broadening the understanding of experimental observations, and expanding the science itself. Some of the breakthroughs involved the creation of new materials. Among these one may enumerate the vulcanization of natural rubber, the derivatization of cellulose, the giant advances right before and during World War II in the preparation and characterization of synthetic elastomers and semi crystalline polymers such as polyesters and polyamides, the subsequent creation of aromatic high-temperature resistant amorphous and semi-crystal line polymers, and the more recent development of liquid-crystalline polymers mostly with n~in-chain mesogenicity. other breakthroughs involve the development of powerful characterization techniques. Among the recent ones, the photon correlation spectroscopy owes its success to the advent of laser technology, small angle neutron scattering evolved from n~clear reactors technology, and modern solid-state nuclear magnetic resonance spectroscopy exists because of advances in superconductivity. The growing need for high modulus, high-temperature resistant polymers is opening at present a new technology, that of more or less rigid networks. The use of such networks is rapidly growing in applications where they are used as such or where they serve as matrices for fibers or other load bearing elements. The rigid networks are largely aromatic. Many of them are prepared from multifunctional wholly or almost-wholly aromatic kernels, while others contain large amount of stiff difunctional residus leading to the presence of many main-chain "liquid-crystalline" segments in the"infinite" network.

Proceedings of an American Chemical Society Division Symposium held in San Francisco, California, April 5-10, 1992

Fractal Aspects of Polymer Networks and Gels.- Fractal Properties of Branched Polymers.- Novel Network Structures: Fractal-Rigid-Flexible Networks.- The Fractal Nature of One-Step Rigid Networks and Their Gels.- Static and Dynamic Light Scattering From Solutions and Gels of RF Particles.- Suppression of Fluctuation-Dominated Kinetics by Mixing.- Rigid and Semiflexible Networks and Gels.- Phase Transitions in Liquid Crystal Polymers.- One-Step and Two-Step Rigid Polyamide Networks and Gels:Similarities and Differences.- New Insights Into Aromatic Polyamide Networks From Molecular Modeling.- Networks With Semi-Flexible Chains.- Mesophase Polysiloxane Networks: Mechanical and Thermomechanical Behavior.- Oriented Liquid Crystalline Network Polymers.- Crosslink Products, Mechanism, and Network Structure of Benzocyclobutene Terminated Bisphenol A Polycarbonates.- Rigid Hypercrosslinked Polystyrene Networks With Unexpected Mobility.- Networks and Gels in Force Fields.- Molecular Modeling of the Mechanical Properties of Crosslinked Networks.- Atomistic Nature of Stress in Polymer Networks.- Investigation of Gelation Processes and Gel Structures by Means of Mechanical Property Measurements.- Theory of Strain-Induced Crystallization in Real Elastomeric Networks.- Kinetics of Gelation Monitored Through Dynamics.- Light Scattering Studies of the Structure of Rigid Polyamide Gels.- Influence of Cure Systems on Dielectric and Viscoelastic Relaxations in Crosslinked Chlorobutyl Rubber.- Flexible Networks and Gels.- Network Formation Theories and Their Application to Systems of Industrial Importance.- Osmotic Properties of Swollen Polymer Networks.- Cyclization During Crosslinking Free-Radical Polymerizations.- Novel Polyfunctional Isocyanates for the Synthesis of Model Networks.- Comparison Between Lightly Crosslinked Ionomeric Materials and Highly Crosslinked Materials Derived From Poly (acrylic acid) With Organostannanes as the Crosslinking Agent.- Contributors.