Characterization of commercial aliphatic hyperbranched polyesters

Žagar, Ema; Žigon, Majda; Podzimek, Štěpán

doi:10.1016/j.polymer.2005.10.142

Cited by 103 publications

(97 citation statements)

References 47 publications

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“…Random statistical procedures are commonly used to study the structure of hyperbranched polymers, but a series of deviations from the ideal situation are expected due to subsitution effects during polymerization, the occurrence of side reactions and intramolecular cyclization [18][19][20][21][22][23][24][25]. The high mass-average molecular weight and polymer dispersity of the resulting polymes can be controlled by means of the addition of small core molecules [18,19,26], a feature that can be easily incorporated into statistical models.…”

Section: Introductionmentioning

confidence: 99%

“…The high mass-average molecular weight and polymer dispersity of the resulting polymes can be controlled by means of the addition of small core molecules [18,19,26], a feature that can be easily incorporated into statistical models. The use of highly branched precursors in polymer networks, including hyperbranched polymers, has been rigorously studied from a theoretical point of view by Dušek and co-workers [27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

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Structural analysis of the curing of epoxy thermosets crosslinked with hyperbranched poly(ethyleneimine)s

Fernández‐Francos

Ramis

2015

European Polymer Journal

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The network build-up process during curing of an epoxy resin using a hyperbranched poly(ethyleneimine) as crosslinking agent has been studied from a theoretical and experimental point of view. A systematic analysis taking into account the stoichiometry of the curing process has been performed. Conversion at gelation has been studied by thermomechanical analysis (TMA) and differential scanning calorimetry (DSC). Crosslinking density has been studied by dynamomechanical analysis (DMA). Gel fraction after extraction in organic solvents has also been determined. The experimental results have been compared with a theoretical network build-up model based on the random recombination of structural fragments, showing good agreement between theory and experimental results, but deviations from the ideal epoxy-amine polycondensation appear as a consequence of the dilution of the hyperbranched crosslinker in off-stoichiometric formulations.  Expressions for relevant pre-gel and post-gel statistical averages are derived.  Experimental validation of predicted crosslinking and gelation is performed.  Nonidealities due to the densely branched structure of the crosslinker are described. ABSTRACTThe network build-up process during curing of an epoxy resin using a hyperbranched poly(ethyleneimine)as crosslinking agent has been studied from a theoretical and experimental point of view. A systematic analysis taking into account the stoichiometry of the curing process has been performed. Conversion at gelation has been studied by thermomechanical analysis (TMA) and differential scanning calorimetry (DSC). Crosslinking density has been studied by dynamomechanical analysis (DMA). Gel fraction after extraction in organic solvents has also been determined. The experimental results have been compared with a theoretical network build-up model based on the random recombination of structural fragments,showing good agreement between theory and experimental results, but deviations from the ideal epoxyamine polycondensation appear as a consequence of the dilution of the hyperbranched crosslinker in offstoichiometric formulations.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural analysis of the curing of epoxy thermosets crosslinked with hyperbranched poly(ethyleneimine)s

Fernández‐Francos

Ramis

2015

European Polymer Journal

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“…As we know, when PNIPAM chains are attached by one end to a flat substrate or curved interface with sufficient density, referred to as a polymer brush, they are crowned and forced to stretch away from the surface to avoid overlapping. In our case, the molecular size of HPG is estimated to be B3 nm; 35,66,76 the grafting of 42 PNIPAM chains from the HPG core results in a densely packed PNIPAM brush surrounding the hydrophilic core and the grafting density can be calculated as B0.67 nm 2 per chain. Therefore, for HPG-PNIPAM, because of the grafted chain crowding and steric repulsion of neighboring chains in the brush, the results of dynamic LLS show a broad phase transition range from 20 to 34 1C.…”

Section: Thermoresponsivity Of Unimolecular Polymeric Micellesmentioning

confidence: 76%

“…Hyperbranched polymers, which are the imperfect analogs of dendrimers, can be used as a potential alternative because they can be obtained conveniently in a single step and in high yield. 20,[33][34][35] From a practical point of view, the amphiphilic hyperbranched macromolecules have potential practical applications. [36][37][38] Therefore, it is interesting to use hyperbranched polymers as the favorable starting materials for the synthesis of a globular amphiphile with unimolecular micellar properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of thermoresponsive unimolecular polymeric micelles with a hydrophilic hyperbranched poly(glycidol) core

Luo

Zhang

et al. 2010

Polym J

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This paper describes the reversible phase transition behavior of a thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) shell at the surface of a hydrophilic core. Reversible addition-fragmentation transfer (RAFT) polymerization of N-isopropylacrylamide was conducted using a hydrophilic hyperbranched poly(glycidol) (HPG)-based macroRAFT agent. At lower temperatures (o30 1C), the resultant multiarm star block copolymer (HPG-PNIPAM) exists as unimolecular micelles, with hydrophilic HPG as the core and a densely grafted PNIPAM brush as the shell. In laser light scattering (LLS) studies, the concentration used for HPG-PNIPAM is 5Â10 À6 g ml À1 , to avoid any possible aggregation between dendritic unimolecular micelles above the lower critical solution temperature (B32 1C) of PNIPAM. What we observe for the phase transition of HPG-PNIPAM involves only unimolecular process. A combination of dynamic and static LLS studies of HPG-PNIPAM in aqueous solution reveals a reversible phase transition on heating and cooling.

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“…El HBPAM, presentó una perdida (14 %), la cual aparece entre 125 y 206°C; está perdida es debida a la descomposición térmica de compuestos de bajo peso molecular (cadenas de HBPAM que posiblemente experimentaron reacciones de intercambio hidroxi-ester, o unidades de HBPAM que reaccionaron a través de una reacción de eterificación intermolecular), esto ya ha sido observado para poliésteres polioles altamente ramificados [23], [24]. Este compuesto presenta una segunda perdida a 275°C (86 %), la cual es atribuida a compuestos de mayor peso molecular (HBP con unidades de AM injertadas).…”

Section: El Amunclassified

Polietileno de baja densidad funcionalizado con un poliéster poliol altamente ramificado maleinizado

Ararat

Murillo

2016

ing.cienc.

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ResumenEn este trabajo, polietileno de baja densidad (PEBD) fue modificado en estado fundido con un poliester poliol altamente ramificado maleinizado (HBPAM), usando varias proporciones de peróxido de dicumilo (0.5, 1.0, 1.5 y 2.0 %). El análisis infrarrojo mostró las señales de grupos OH, C=O, -COOR y -C=C-del HBPAM en el espectro de las muestras funcionalizadas (PEBD-g-HBPAM). El grado de injerto (GI) fue entre 9.14 y 9.82 %. El índice de fluidez de las muestras PEBD-g-HBPAM fue más bajo que el del PEBD, y no exhibió una dependencia con el contenido de peróxido de dicumilo y GI. Excepto para la muestra obtenida con un 2.0 % de peróxido de dicumilo, todas las temperaturas de fusión de las muestras de PEBD-g-HBPAM fueron similares a la del PEBD. La entalpia de fusión de las muestras de PEBD-g-HBPAM disminuyó con la concentración de peróxido de dicumilo y GI. El módulo ténsil de estas muestras fue más alto que el del PEBD, pero la elongación a la ruptura fue más baja.

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Characterization of commercial aliphatic hyperbranched polyesters

Cited by 103 publications

References 47 publications

Structural analysis of the curing of epoxy thermosets crosslinked with hyperbranched poly(ethyleneimine)s

Structural analysis of the curing of epoxy thermosets crosslinked with hyperbranched poly(ethyleneimine)s

Synthesis of thermoresponsive unimolecular polymeric micelles with a hydrophilic hyperbranched poly(glycidol) core

Polietileno de baja densidad funcionalizado con un poliéster poliol altamente ramificado maleinizado

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