Degree of branching in hyperbranched polymers
作者:
D. Hölter,
A. Burgath,
H. Frey,
期刊:
Acta Polymerica
(WILEY Available online 1997)
卷期:
Volume 48,
issue 1‐2
页码: 30-35
ISSN:0323-7648
年代: 1997
DOI:10.1002/actp.1997.010480105
出版商: Akademie Verlag GmbH
数据来源: WILEY
摘要:
AbstractTopological considerations concerning the ratio of linear, imperfectly branched, dendritic and terminal units in hyperbranched polymers based on AB2, AB3and ABm(m≥2) type monomers are summarized. The reaction of AB2monomers with a core molecule of the structure Bfis also treated. For larger hyperbranched polymers based on AB2monomers the fraction of terminal units has to be equal to the number of dendritic units. A general expression for the degree of branching (DB) is derived for AB2systems, which is based on the number of dendritic and linear units. The expression is valid for low molecular weight as well as high molecular weight hyperbranched polymers in contrast to the commonly used expression based on dendritic, linear and terminal units. DB may not exceed 0.5 in hyperbranched polymers based on AB2systems (0.44 in AB3systems). Furthermore, a general expression for DB in hyperbranched polymers based on ABmmonomers is derived. Consequences for signal ratios in NMR‐spectra of hyperbranched polymers are discussed. The expressions presented allow verification of NMR‐integration ratios obtained experimentally on the basis of model comp
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