A study of the radical polymerization of styrene macromonomers having a methacryloyl end group (MA-PSt; Aí" = 4400,12 400) and a vinylbenzyl end group (VB-PSt; Aí" = 4980,13 200) was carried out by using gel permeation chromatography with a laser light scattering detector (LS-GPC) and electron spin resonance spectroscopy (ESR). It was shown that the degree of polymerization of poly(macromonomer)s (Dp) measured by LS-GPC drastically varied with the macromonomer concentration in the feed ([M]); however, there was little difference in the Dp versus [M] curves between MA-PSt and VB-PSt of the same molecular weight. The Dp of poly(macromonomer)s was small (typically less than 10) at low [M] and increased rapidly with an increase in [M] followed by the sudden decrease to Dp = 1 at very high [M], The Dp versus [M] relationship was strongly affected by the molecular weight (Mw) of the macromonomers. These Dp versus[M] relationships were quite similar to Dp (or Rp) versus the degree of conversion relationship of the polymerization system of conventional small monomers in the presence of the gel effect. This indicated that the diffusion-controlled effect in macromonomer systems could be clearly described by [M] and Mv of the macromonomer.It was also shown that time-conversion curves of these macromonomers were monotonic and exhibited no feature of the autoacceleration effect normally observed in the polymerization system of small monomers in the presence of the gel effect. In addition, the polymerization rate (Rp) of MA-PSt was considerably greater than that of VB-PSt of the same molecular weight. ESR spectra of the propagating radical of MA-PSt and VB-PSt were measured to evaluate the concentration of the propagating radicals.From the results of ESR and LS-GPC, the propagation rate constant kp, the termination rate constant kt, and the radical lifetime rp of the macromonomers are evaluated and discussed.

A local segmental mobility was determined by electron spin resonance (ESR) spin-label method for a series of polystyrene (PS) with various molecular weights. Each PS specimen was selectively spin-labeled with stable nitroxide radicals at a chain end or inside sites. Molecular motion at the inside of the chain was compared with that at the chain end from the temperature dependence of ESR spectra of the nitroxide radicals. The transition temperature of molecular motion, T 5.0mT, at which the extreme separation width due to 14 N anisotropic hyperfine splitting is 5.0 mT, increased with an increase in molecular weight. The WLF equation confirmed that the T5.0mT correlated with a glass transition temperature, Tg, of PS. The T5.0mT for the spin-labeled PS at the chain end was ca. 5 K lower than that for the spin-labeled PS at the inside sites due to the enrichment of the specific free volume around the chain end. The transition temperature, T5.0mT, for both labeled PS depended on the molecular weight in accordance with the Unberreiter-Kanig equation for a glass transition. The T5.0mT for the spin-labeled PS at the chain end had a strong dependence on the molecular weight as compared with that at the inside sites because the molecular motion of the chain end was accelerated by an encounter of more than two chain ends. From the molecular weight dependence, we determined the short correlation time for segmental motion of the chain end, ca. 40 s, and the segment size undergoing the segmental motion at the T g. The obtained segment size agreed well with the general segment size reported by others, 5-10 monomeric unit size.

No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work.Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) PrefaceESR or Electron Spin Resonance is a spectroscopic method for studies of paramagnetic species. Species of this kind are of interest both from fundamental viewpoints and for a broad range of applications in materials and polymer sciences, physical chemistry and chemical physics, bio-chemistry and medicine, catalysis and environmental sciences, radiation dosimetry and geological dating, as well as radiation physics and chemistry. The magnetic properties, mainly attributed to the electron spin, can be employed to determine both the structure (at a molecular level) and the amount of paramagnetic species in a sample with the ESR method. This method has been presented from different viewpoints in the past. Previous monographs on ESR spectroscopy have focused on the technique as such, while the general textbooks in physics, chemistry or spectroscopy only briefly explain the applications, which are mainly presented in specialist reviews and in the original literature. The present book is based upon the authors' long experience of teaching the subject to a mixed audience, with backgrounds ranging from physics to biology. It aims both at providing the principles of continuous wave and pulsed ESR techniques and to illustrate the potential of the method by examples of applications. The principles of ESR, multi-resonance and pulsed ESR methods, the analysis of spectra, and multifrequency and high field ESR techniques treated in the first four chapters are thus followed by five chapters exemplifying recent applications in molecular science, in catalysis and environmental science, in polymer science, in spin labeling and molecular dynamics, and in quantitative ESR.Theoretical derivations are in general left out, as they are presented repeatedly in previous works. The necessary theory is instead illustrated by practical examples from the literature. Commonly used computer codes to evaluate experimental ESR data are described with examples. Internet addresses to download the software are given, whenever possible. Formulae employed in those programs are reproduced in appendices, when the original literature references are not easily available. The theory and the application parts are to a large extent independent of each other to allow study of a special subject. For reasons of easy access of data and diagrams several examples from the authors' own work were employed to illustrate certain applications. Exercises included in the theoretical part are mainly concerned with spectra interpretations, as this is the key issue in the ...