Aromatic−Aliphatic Polyesters with Tailored Degree of Branching Based on AB/AB2 and ABB*/AB2 Monomers

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• 作者：Anna Khalyavina ; Falko Schallausky ; Hartmut Komber ; Michael Al Samman ; Wolfgang Radke ; Albena Lederer
• 刊名：Macromolecules
• 出版年：2010
• 出版时间：April 13, 2010
• 年：2010
• 卷：43
• 期：7
• 页码：3268-3276
• 全文大小：881K
• 年卷期：v.43,no.7(April 13, 2010)
• ISSN：1520-5835

文摘

The synthesis and characterization of aromatic−aliphatic polyesters with tailored degree of branching (DB), i.e. hyperbranched (hb), gradually branched, and linear polymers, are described. The dilute solution properties of polymers resulting from two different synthetic approaches are compared. The ABB*/AB₂ approach leads to homopolymers with different DB based on the same AB₂ monomer, 4,4-bis(4′-hydroxyphenyl)pentanoic acid, employing the protection of one phenolic group (B*) in the AB₂ monomer followed by copolymerization with AB₂ monomer at different molar ratios. Because of their identical chemical origin, well-tunable DB, comparable molar masses, an absence of aggregation in common solvents, and high refractive index increments, they are suitable as model systems in branching characterization. Their solution properties are compared to those of polymers obtained by the AB/AB₂ approach. In order to study the influence of the end-groups on thermal and solution polymer properties, all terminal OH groups were modified with tert-butyldimethylsilyl chloride (SY-Cl). A different dependence of the thermal properties on branching was found for OH- and SY-terminated samples produced by the ABB*/AB₂ approach. While the difference in the T_g values between linear and hb structures was found to be 16 °C for SY-terminated samples, nearly identical values were obtained for OH-terminated linear and hb polyesters due to strong effect of hydrogen bond formation.