Branched Versus Linear Polyisoprene: Flory–Huggins Interaction Parameters for their Solutions in Cyclohexane

Eckelt, John; Samadi, Fatemeh; Wurm, Frederik R.; Frey, Holger; Wolf, Bernhard

doi:10.1002/macp.200900191

Cited by 12 publications

(13 citation statements)

References 44 publications

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“…The volumetric fraction of the rubber was obtained on the basis of equilibrium swelling experiments at 25 ± 0.2 °C using the solvents toluene ( ρ s (toluene) = 865.3 kg m −3 , χ (toluene) = 0.391)31 and cyclohexane ( ρ s (cyclohexane) = 771.1 kg m −3 , χ (cyclohexane) = 0.394) 32. The experimental procedure to determine the gravimetric data was the following.…”

Section: Methodsmentioning

confidence: 99%

Shape‐Memory Natural Rubber: An Exceptional Material for Strain and Energy Storage

Heuwers

Beckel

Krieger

et al. 2013

Macro Chemistry & Physics

108

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Shape‐memory polymers (SMPs) are smart, responsive materials with numerous potential applications. Based on previously introduced shape‐memory natural rubber (SMNR), which shows exceptional properties such as strain storage of 1000%, cold storage, cold programmability, and mechanical and thermal triggers tunable both during and after programming, different SMNRs regarding their shape‐memory parameters are investigated. Furthermore, their energy‐storage capability and their mechanical properties are explored. SMNRs show fixity ratios of up to 94% and excellent recovery ratios of up to 100% whereas strains even above 1000% can be stored. Energies of up to 4.88 J g−1 can be stored with efficiencies of up to 53.30%. Further, the Young's modulus of SMNR can be switched by two orders of magnitude upon triggering or programming.

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Section: Methodsmentioning

confidence: 99%

Shape‐Memory Natural Rubber: An Exceptional Material for Strain and Energy Storage

Heuwers

Beckel

Krieger

et al. 2013

Macro Chemistry & Physics

108

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“…The three parameters of the above equation suffice to describe and to rationalize all experimental findings examined so far: Typical solutions of linear homopolymers14 as well as of linear copolymers (random15 and block16); furthermore it can be applied successfully to branched macromolecules17 and to mixtures of low molecular weight components 18. In the limit of infinite dilution eq 6 simplifies to containing only the leading parameters of the present approach.…”

Section: Theoretical Backgroundmentioning

confidence: 78%

“…This section deals with the question, to which extent the differences in thermodynamic behavior of linear and of branched oligomers, as manifested in vapor pressures, vapor pressure osmometry, and cloud point curves, can be rationalized in terms of molecular architecture. To this end the dissimilar system specific parameters of eq 6 are analyzed for the two types of O‐DMS and the present results are compared with earlier findings17 concerning linear and branched polyisoprenes (PI) of higher molar mass and lower branching density.…”

Section: Resultsmentioning

confidence: 94%

Branched versus linear oligo(dimethylsiloxane): Differences in their thermodynamic interaction with solvents

Samadi

Eckelt

Wolf

et al. 2010

J Polym Sci B Polym Phys

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The thermodynamic behavior of linear and of branched oligo(dimethylsiloxane) (O‐DMS) solutions was studied by means of vapor pressure measurements and vapor pressure osmometry at different temperatures for the thermodynamically favorable solvent THF. The branched material required for that purpose was synthesized and afterwards fractionated by means of the single solvent acetone to eliminate components of low degrees of branching. The Flory‐Huggins interaction parameters, χ, for the systems THF/O‐DMS as a function of composition pass a minimum at all temperatures (25, 40, and 60 °C) in the case of the branched material. For the unbranched oligomer such a minimum is only observed at 60 °C. At 40 °C the results are ambigous whereas the dependence is definitely linear at 25 °C. This exceptional behavior of the linear product at the latter temperature is tentatively attributed to the formation of favorable orientational order in the pure state under these conditions. At high oligomer concentrations THF interacts more favorably with the branched material, however, this preference is reversed upon dilution. All measured composition dependencies of χ can be modeled quantitatively by an approach accounting for chain connectivity and for the ability of the oligomers to change their conformation upon dilution. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1309–1318, 2010

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“…According to Raoult's law, the vapour pressure of the considered solution should change linearly (straight line in Figure 1) from the vapour pressure of the solvent to zero pressure, because the vapour pressure of the pure polymer is zero. However, the experimental data, taken from the literature [61], are far away from Raoult's law. Additionally, the experimental data in Figure 1 clearly shows the impact of polymer architecture on the thermodynamic properties.…”

Section: Flory-huggins Theorymentioning

confidence: 99%

“…They figured out that there are significant differences in the cloud point pressure. Vapour pressure measurements for polymer solutions made from polyisoprene (linear and branched) and cyclohexane, performed by Eckelt et al [61], demonstrates the influence of the degree of branching on the solution properties. According to these results [59][60][61] it can be stated that the calculation of phase equilibria of branched polymers needs the consideration of polymer architecture in the thermodynamic equations.…”

Section: Introductionmentioning

confidence: 98%

Phase Diagrams for Systems Containing Hyperbranched Polymers

et al. 2012

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Abstract:Hyperbranched polymers show an outstanding potential for applications ranging from chemistry over nanotechnology to pharmacy. In order to take advantage of this potential, the underlying phase behaviour must be known. From the thermodynamic point of view, the modelling of these phase diagrams is quite challenging, because the thermodynamic properties depend on the architecture of the hyperbranched polymer as well as on the number and kind of present functional end groups. The influence of architecture can be taken into account via the lattice cluster theory (LCT) as an extension of the well-known Flory-Huggins theory. Whereas the Flory-Huggins theory is limited to linear polymer chains, the LCT can be applied to an arbitrary chain architecture. The number and the kind of functional groups can be handled via the Wertheim perturbation theory, applicable for directed forces between the functional groups and the surrounding solvent molecules. The combination of the LCT and the Wertheim theory can be established for the modelling or even prediction of the liquid-liquid equilibria (LLE) of polymer solutions in a single solvent or in a solvent mixture or polymer blends, where the polymer can have an arbitrary structure. The applied theory predicts large demixing regions for mixtures of linear polymers and hyperbranched polymers, as well as for mixtures made from two hyperbranched polymers. The introduction of empty lattice sites permits the theoretical investigation of pressure effects on phase behaviour. The calculated phase diagrams were compared with own experimental data or to experimental data taken from literature. OPEN ACCESSPolymers 2012, 4 73

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Branched Versus Linear Polyisoprene: Flory–Huggins Interaction Parameters for their Solutions in Cyclohexane

Cited by 12 publications

References 44 publications

Shape‐Memory Natural Rubber: An Exceptional Material for Strain and Energy Storage

Shape‐Memory Natural Rubber: An Exceptional Material for Strain and Energy Storage

Branched versus linear oligo(dimethylsiloxane): Differences in their thermodynamic interaction with solvents

Phase Diagrams for Systems Containing Hyperbranched Polymers

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