Volumes of aqueous block copolymers based on poly(propylene oxides) and poly(ethylene oxides) in a large temperature range: A quantitative description

Lisi, R. De; Lazzara, Giuseppe; Milioto, Stefana; Muratore, Nicola

doi:10.1016/j.jct.2006.02.002

Cited by 10 publications

(9 citation statements)

References 44 publications

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“…By integrating the E U,C and E U,CD data, we calculated the volume changes for the copolymer self-aggregation processes (DV M ) and CD dethreading (DV D ), respectively. The DV M value for the T1107 in water has the same order of magnitude than that measured for PEO, PPO-based copolymer in isothermal conditions [33].…”

Section: Apparent Molar Volume and Compressibilitysupporting

confidence: 56%

Thermodynamics of cyclodextrin–star copolymer threading–dethreading process

Lazzara

Milioto

Schimmenti

2015

J Therm Anal Calorim

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Section: Apparent Molar Volume and Compressibilitysupporting

confidence: 56%

Thermodynamics of cyclodextrin–star copolymer threading–dethreading process

Lazzara

Milioto

Schimmenti

2015

J Therm Anal Calorim

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“…0.02 mol kg -1 may be ascribed to the L64 aggregation. 23 A further analysis of the plots in Figure 1 highlights that the ∆V t,CD values increase in magnitude with the copolymer molecular weight (MW p ) and the copolymer hydrophilicity.…”

Section: Resultsmentioning

confidence: 90%

Copolymer−Cyclodextrin Inclusion Complexes in Water and in the Solid State. A Physico-Chemical Study

Lazzara

Milioto

2008

J. Phys. Chem. B

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The formation of inclusion complexes (ICs) composed of cyclodextrins (CDs) and poly(ethylene oxides)-poly(propylene oxides)-poly(ethylene oxides) (PEO-PPO-PEO) was studied. To this purpose, native and hydroxypropyl cyclodextrins with different cavity size were chosen. The PEO-PPO-PEO copolymers were selected to study the role of the molecular weight, keeping constant the hydrophilic/hydrophobic ratio, and the hydrophilicity. The volumetric studies at 25 degrees C allowed to determine the equilibrium constant and the volume change for the IC formation in water as well as the IC stoichiometry. Surface tension experiments evidenced that the copolymer and the CD interfacial behavior is controlled by the formation of ICs taking place in the bulk phase. It was proved that the differential scanning calorimetry (DSC) is a valid method to describe quantitatively the IC in the solid state. The combination of volumes, DSC and FTIR techniques together with the geometric information highlighted the following points: (1) the included copolymer is in the amorphous state; (2) the IC composed of native CDs adopts a channel structure with two EO units incorporated into one CD molecule; (3) the IC composed of hydroxypropyl-cyclodextrin is a polymeric structure like a necklace decorated with CD rings. Finally, TGA experiments showed that the thermal stability of the IC depends on the nature of both components.

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“…Experiments almost always measure the heat capacity at constant pressure C p , which has been shown by Artyomov and Freed 10 to be considerably less than incompressible model predictions for the heat capacity C (C ≈ 1.4C p ) by extending a Flory-Huggins type model to compressible systems to accommodate the volume change on polymerization or micellization. 11 They note that the approximate relation of Wheeler et al 12 for the extent of polymerization (equivalent to micellization) Φ predicted from an incompressible model would be larger by the factor 1.4 when measuring C p in a compressible system,…”

Section: B Heat Capacity and Enthalpymentioning

confidence: 98%

Heat capacity anomaly in a self-aggregating system: Triblock copolymer 17R4 in water

Dumancas

Simpson

Jacobs

2015

The Journal of Chemical Physics

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The reverse Pluronic, triblock copolymer 17R4 is formed from poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO): PPO14 - PEO24 - PPO14, where the number of monomers in each block is denoted by the subscripts. In water, 17R4 has a micellization line marking the transition from a unimer network to self-aggregated spherical micelles which is quite near a cloud point curve above which the system separates into copolymer-rich and copolymer-poor liquid phases. The phase separation has an Ising-like, lower consolute critical point with a well-determined critical temperature and composition. We have measured the heat capacity as a function of temperature using an adiabatic calorimeter for three compositions: (1) the critical composition where the anomaly at the critical point is analyzed, (2) a composition much less than the critical composition with a much smaller spike when the cloud point curve is crossed, and (3) a composition near where the micellization line intersects the cloud point curve that only shows micellization. For the critical composition, the heat capacity anomaly very near the critical point is observed for the first time in a Pluronic/water system and is described well as a second-order phase transition resulting from the copolymer-water interaction. For all compositions, the onset of micellization is clear, but the formation of micelles occurs over a broad range of temperatures and never becomes complete because micelles form differently in each phase above the cloud point curve. The integrated heat capacity gives an enthalpy that is smaller than the standard state enthalpy of micellization given by a van't Hoff plot, a typical result for Pluronic systems.

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Volumes of aqueous block copolymers based on poly(propylene oxides) and poly(ethylene oxides) in a large temperature range: A quantitative description

Cited by 10 publications

References 44 publications

Thermodynamics of cyclodextrin–star copolymer threading–dethreading process

Thermodynamics of cyclodextrin–star copolymer threading–dethreading process

Copolymer−Cyclodextrin Inclusion Complexes in Water and in the Solid State. A Physico-Chemical Study

Heat capacity anomaly in a self-aggregating system: Triblock copolymer 17R4 in water

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