Branched polyesters: recent advances in synthesis and performance

McKee, Matthew G.; Ünal, Serkan; Wilkes, Garth L.; Long, Timothy Edward

doi:10.1016/j.progpolymsci.2005.01.009

Cited by 277 publications

(267 citation statements)

References 142 publications

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“…Unfortunately, because it has generally proved impossible to determine DB by either solution or solid state 13 C NMR, average contraction factors parameters such as and ′ , have typically been used in previous literature reports to describe the DB of the branched polymers. 1,[46][47] The mathematical equations that describe these parameters can be found in the ESI (Section S.4). They are calculated based on the mean radius of gyration and intrinsic viscosity of the polymer respectively, where the mean square radius of gyration ‹ 2 › is related to the hydrodynamic volume of a polymer, 44,47 and is measured using light scattering methods.…”

Section: Degree Of Branching (Db) By Gpc-malls and Gpc-viscometermentioning

confidence: 99%

“…1,[46][47] The mathematical equations that describe these parameters can be found in the ESI (Section S.4). They are calculated based on the mean radius of gyration and intrinsic viscosity of the polymer respectively, where the mean square radius of gyration ‹ 2 › is related to the hydrodynamic volume of a polymer, 44,47 and is measured using light scattering methods. At the same molecular weight, is defined as the ratio of 2 of a branched species compared to that of a linear polymer.…”

Section: Degree Of Branching (Db) By Gpc-malls and Gpc-viscometermentioning

confidence: 99%

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Facile one-spot synthesis of highly branched polycaprolactone

et al. 2014

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Reported is the first solvent-free (bulk) synthesis of degradable/bioresorbable, highly branched polymers via tin octanoate Sn(Oct 2 ) catalysed controlled ring opening copolymerisation (ROP) of mono and di-functional lactone monomers that proceed to near quantitative conversion. The successful isolation of solvent soluble, highly branched structures was shown to be dependent on both the concentration of the di-functional monomer and the overall reaction time. Comparison with analogous systems utilising controlled radical polymerisation (CRP) to form the highly/hyper branched polymers suggested significant experimental differences between the two chain growth methods. The maximum proportion of di-functional monomer without gelation ensuing was found to be 0.6 equivalents w.r.t. mono-functional monomer (c.f. 1 with CRP) and the onset of significant levels of branching occurred at approximately 90% conversion (c.f. ~70% with CRP). These differences and significant disparity in reaction times were attributed to (a) the coordination and insertion (C+I) propagation mechanism adopted by the Sn catalyst and (b) the presence of additional trans-esterification reactions at high conversion. Evidence is presented to support the conclusion that there are two mechanisms contributing to the overall branching process in the ROP system at high conversion. First, the C+I mechanism promotes growth of linear polymer until approximately 90% conversion, after which both the C+I and transesterification processes contribute to the interchain branching process. The branched nature of the molecular structures was supported by confirmation plots generated from static light scattering. This data demonstrated that the polymers synthesised exhibit varying degrees of branching, consistent with the di-functional monomer (4, concentration in the feed. The degree of branching was calculated using 3 different methods 2 and the results were shown to be independent of method. Finally, DSC analysis of the polymers demonstrated correlation between the degree of branching achieved and the observed T m for the material where increased branching leads to a drop in the recorded T m .

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Section: Degree Of Branching (Db) By Gpc-malls and Gpc-viscometermentioning

confidence: 99%

Section: Degree Of Branching (Db) By Gpc-malls and Gpc-viscometermentioning

confidence: 99%

Facile one-spot synthesis of highly branched polycaprolactone

et al. 2014

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“…Their physical properties such as solubility in different solvents or glass transition temperature can be easily tailored by chemical modification of the functional end groups. In contrast to hyperbranched polyesters, 12 they are much more stable against acidic or basic hydrolysis. Thus, in the last two decades, hyperbranched polymers have attracted increasing attention from both an academic and industrial point of view, because of their high potential for advanced nanomaterials, novel biomaterials, and as rheology modifiers.…”

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confidence: 94%

Hyperbranched aliphatic polyether polyols

Schömer

Schüll

Frey

2012

J. Polym. Sci. A Polym. Chem.

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Hyperbranched polymers, dendritic macromolecules with branch-on-branch structures, have become an important polymer class since the early 1990s. They combine several advantages of the perfectly branched dendrimers with easy accessibility, typically in a one-step synthesis. Hyperbranched polyethers are a particularly interesting class of chemically stable and often biocompatible materials. Multifunctional hyperbranched polyethers with controllable molar mass and comparably low polydispersities can been prepared using hydroxyl-functional epoxides or oxetanes for polymerization via anionic and cationic polymerization mechanisms. Here, we review the progress in the preparation, characterization, and application of these uniquely versatile aliphatic polyether polyols. Their unusual mechanical, thermal, and solution properties render them useful for a variety of applications, for example, as building blocks for various complex macromolecular architectures or in biomedical applications.

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“…The hydrophobic core serves as a carrier environment for hydrophobic drugs, and the hydrophilic outer shell stabilizes the micelles in solution [6,7]. Although most of the amphiphilic copolymers studied for drug delivery system are made of block copolymers, graft copolymers have gained increasing attention due to the adjustable backbone and side chains [8,9]. In particular, graft copolymers containing a great quantity of side chains chemically attached onto a linear backbone possess confined and compact structures compared with block copolymers [10,11].…”

Section: Introductionmentioning

confidence: 99%

Fluorescence Studies on Self-association of Biodegradable Pyrene-labeled Poly(L-lysine) Grafted with Poly(caprolactone)

Kimura

Fukushima

2014

J. Photopol. Sci. Technol.

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The biodegradable amphiphilic graft copolymer (PolyLysPy-PCL) containing hydrophilic pyrene end-labeled poly(L-lysine) (PolyLysPy) backbone and hydrophobic polycaprolactone (PCL) side chains was synthesized by the amide condensation of PolyLysPy and PCL. PolyLysPy was prepared from ring-opening polymerization of N-ε-benzyloxycarbonyl-L-lysine N-carboxyanhydride (Lys(Z)-NCA) initiated by 1-pyrenemethylamine and followed by removing the side-chain protective groups. PCL was prepared from the enzymatic ring-opening polymerization of ε-caprolactone by a porcine pancreas lipase. The structures and number-average molecular weights (Mn) of the graft copolymer and its precursors were confirmed and investigated by the 1 H NMR measurement. The self-assembly of the graft copolymer in water/DMSO mixture solution was examined by fluorescent signals assigned to the pyrene moiety. The increase in the grafting percent of PCL to a PolyLysPy polymer backbone can facilitate the self-assembly by the hydrophobic interaction of associated PCL grafts.

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Branched polyesters: recent advances in synthesis and performance

Cited by 277 publications

References 142 publications

Facile one-spot synthesis of highly branched polycaprolactone

Facile one-spot synthesis of highly branched polycaprolactone

Hyperbranched aliphatic polyether polyols

Fluorescence Studies on Self-association of Biodegradable Pyrene-labeled Poly(L-lysine) Grafted with Poly(caprolactone)

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