Role of cyclization in the synthesis of hyperbranched aliphatic polyesters

Burgath, Armin; Sunder, Alexander; Frey, Holger

doi:10.1002/(sici)1521-3935(20000401)201:7<782::aid-macp782>3.0.co;2-o

Cited by 113 publications

(13 citation statements)

References 16 publications

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“…Among them, reactions of closure of linear chains are of particular interest since they are involved in a number of chemical and biological processes. Examples cover gene regulation by the formation of RNA-hairpins [1,2] or DNA-loops [3,4], the folding of polypeptides [5,6], as well as the appearance of cycles in synthetic polymers [7][8][9]. In the diffusion-controlled regime, the kinetics of contact formation strongly depends on the complex dynamics of the reactive monomers.…”

Section: Introductionsupporting

confidence: 62%

Non-Markovian closure kinetics of flexible polymers with hydrodynamic interactions

Levernier

Dolgushev

Bénichou

et al. 2015

The Journal of Chemical Physics

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This paper presents a theoretical analysis of the closure kinetics of a polymer with hydrodynamic interactions. This analysis, which takes into account the non-Markovian dynamics of the end-toend vector and relies on the preaveraging of the mobility tensor (Zimm dynamics), is shown to reproduce very accurately the results of numerical simulations of the complete non linear dynamics. It is found that Markovian treatments, based on a Wilemski-Fixman approximation, significantly overestimate cyclization times (up to a factor 2), showing the importance of memory effects in the dynamics. In addition, this analysis provides scaling laws of the mean first cyclization time (MFCT) with the polymer size N and capture radius b, which are identical in both Markovian and non-Markovian approaches. In particular, it is found that the scaling of the MFCT for large N is given by T ∼ N 3/2 ln(N/b 2 ), which differs from the case of the Rouse dynamics where T ∼ N 2 . The extension to the case of the reaction kinetics of a monomer of a Zimm polymer with an external target in a confined volume is also presented.

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Section: Introductionsupporting

confidence: 62%

Non-Markovian closure kinetics of flexible polymers with hydrodynamic interactions

Levernier

Dolgushev

Bénichou

et al. 2015

The Journal of Chemical Physics

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“…This observation evidently supports its branched structure of smaller hydrodynamic volume compared to linear polystyrene standard. [13,14] MALDI-ToF analysis further confirmed that 4 indeed bears nearly ten to eleven (trifluoroacetyl)azobenzene residues. Model compound 5 was synthesized following the method, outlined in Schemes 2 to compare the recognition property (Supporting Information: Experimental).…”

Section: Resultsmentioning

confidence: 83%

Chromogenic Signaling of Amine and Diamine with Hyperbranched Polymer Bearing (Trifluoroacetyl)azobenzene Surface Units

Ghosh

Manna

2016

ChemistrySelect

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“…This value was set to 100% for the degradation experiments, and the relative amount of fatty acid released by hydrolysis or enzymatic degradation was calculated from this value. It is worth mentioning that several research groups have reported discrepancies associated with the experimentally determined number of end groups, number‐average molecular weights, and degree of branching of hyperbranched polymers and the theoretical values 17, 18, 41. For the calculation of the amount of fatty acids present in the polymer, the experimental values of the molar mass of the core polymer and the number of hydroxyl groups from Žagar and Žigon16, 17 were considered.…”

Section: Resultsmentioning

confidence: 99%

“…All solvents used in this study were analytical-grade and were used as received. The total amount of fatty acids a Molecular weight (a) was calculated on the basis of the theoretical core-to-monomer ratio, (b) was calculated with the core polymer molar mass determined by the vapor pressure osmometry (data of Burgath et al 41 ), and (c) was calculated with the core polymer molar mass determined by the size exclusion chromatography with detection by multiangle light scattering data of Ž agar and Ž igon. 16,17 b Determined by DSC.…”

Section: Methodsmentioning

confidence: 99%

Enzymatic degradation of hyperbranched polyesters

Mallepally

Смирнова

Arlt

et al. 2009

J of Applied Polymer Sci

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In this work, the enzyme-catalyzed degradation of hyperbranched polyesters (HBPEs) was investigated. Enzymatic degradation experiments were performed in a phosphate buffer in the presence of the lipases Candida cylindracea, Pseudomonas cepacia, Novozym 388, Amano CE, Lipomod 34P, and Cal-B, whereas control experiments were performed in the same system without lipases. The extent of polymer degradation was determined by quantification of the released free fatty acids by gas chromatography. The influence of the alkane chain length and the number of alkane chain end groups on the lipase-catalyzed hydrolysis of esterified HBPEs was investigated systematically. It was found that the increase in the alkane chain length of the end groups diminished the enzymatic degradation of the polymer, whereas the number of end groups had no influence on the degradation rate. The effect of temperature on the rate of degradation was also described. Surface morphological changes that occurred during the degradation were assessed with reflected electron microscopy. The changes in the crystallinity of the polymers after they were subjected to degradation were qualitatively determined with differential scanning calorimetry through the quantification of the enthalpy of melting. The enthalpy of melting of one HBPE sample increased from 79 to 90 and 94 J/g with and without the action of Lipomod 34P, respectively, in 7 days, showing the changes in the crystallinity of the polymer. The results prove that modified HBPEs are an important new class of biodegradable materials with a predictable degradation mechanism, and the degradation can be adjusted on the basis of the molecular engineering.

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Role of cyclization in the synthesis of hyperbranched aliphatic polyesters

Cited by 113 publications

References 16 publications

Non-Markovian closure kinetics of flexible polymers with hydrodynamic interactions

Non-Markovian closure kinetics of flexible polymers with hydrodynamic interactions

Chromogenic Signaling of Amine and Diamine with Hyperbranched Polymer Bearing (Trifluoroacetyl)azobenzene Surface Units

Enzymatic degradation of hyperbranched polyesters

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