Hyperbranched Poly(ε-caprolactone)s

Abstract

Novel hyperbranched poly(ε-caprolactone)s have been synthesized. The versatile synthesis utilizes AB2 macromonomers and allows the thermo-physical properties of the polymers to be tailored. The ε-caprolactone-based AB2 macromonomers were synthesized through living ring opening polymerization, using aluminum benzyloxide as the initiator. The aluminum benzyloxide initiated polymers were then functionalized with benzylidene-protected 2,2‘-bis(hydroxymethyl) propionic acid and subsequently deprotected to form the α-carboxylic-ω-dihydroxy functional AB2 macromonomers. The AB2 polyesters were condensed into hyperbranched polymers through a room-temperature esterification synthesis using dicyclohexylcarbodiimide (DCC) and 4-(dimethylamino)pyridinium 4-toluenesulfonate (DPTS). All polymers were characterized by 1H NMR, SEC, and DSC. The degree of branching in the hyperbranched polymers was found, by 1H NMR, to be 0.37 ± 0.03, and to be independent of the macromonomer used. Significant flexibility exists in the new approach since the molecular weight and the type of macromonomer can be varied.

Polyester Dendrimers

“…Polyester dendrimers were prepared up to the fourth generation using even sterically congested cores like pentaerythritol in good yields using DMAP and DCC to promote ester formation. Since then, a number of research groups have utilized the benzylidene-protected bis-HMPA as a convenient building block [127,129,130,146,[150][151][152][153]. Synthesis of a dendritic macro-initiator for atom transfer radical polymerization [146].…”

Synthesis of Hyperbranched Poly(ε-caprolactone) Containing Terminal Azobenzene Structure via Combined Ring-Opening Polymerization and “Click” Chemistry

“…Compared with dendrimers obtained from step-by-step synthesis, hyperbranched polymers could be considered as irregular analogues of the dendrimers with narrow polydispersity and predictable molecular weights [16], Moreover, hyperbranched polymers can easily be synthesized by direct one-pot polymerization based on functional ABx-type (x ≥ 2) monomers [17,18], which were better suited for application in highly functionalized globular production. Recently, hyperbranched PCLs (HPCLs) have been increasingly studied, because a homologous series of HPCLs with a range of molecular architectural variations (i.e., different lengths of linear backbone segments and different numbers of branching points) could be obtained by a series of novel synthetic approaches [19][20][21]. For instance, a series of HPCLs were synthesized through the moisture-sensitive catalyst-free polycondensation of AB2 macromonomers, and Jeongsoo Choi et al [22] investigated the thermal characteristics of HPCLs in conjunction with their branching features.…”

“…In 2004, Jeongsoo Choi and his colleagues [23] conducted a detailed study on the crystallization behaviors of three HPCLs with different molecular architectures. However, few methods are available to synthesize HPCLs [19][20][21][22][23].…”

Facile one-spot synthesis of highly branched polycaprolactone

“…[27][28] This author also reported the synthesis of a second CL based AB 2 macromonomer via ring-opening polymerisation (ROP) of CL, using benzyl ester protected MPA and tin octanoate (Sn(Oct) 2 ). 28 Frechet et al reported the preparation of 4-(2-hydroxyethyl)-caprolactone which was then used to produce hyperbranched polyester in a one-pot strategy.…”