Transport in intermediate and high molecular weight hydroxypropylcellulose/water solutions

Phillies, George D. J.; Richardson, C.G.; Quinlan, Carol Ann; Ren, Shisong

doi:10.1021/ma00077a022

Cited by 53 publications

(76 citation statements)

References 15 publications

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“…The coupling model successfully predicts some experimental results on probe diffusion in polymer solutions 11,15,17 and on polymer self-diffusion. 36 -38 First, stretched-exponential functions of (t) describe well g (1) (t) of many polymer systems.…”

Section: Coupling/scaling Analysismentioning

confidence: 70%

Relaxational mode structure for optical probe diffusion in high molecular weight hydroxypropylcellulose

Streletzky

Phillies

1998

J. Polym. Sci. B Polym. Phys.

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We studied translational diffusion of dilute monodisperse spheres (diameters 14 < d < 455 nm) in aqueous 1 MDa hydroxypropylcellulose (0 ≤ c ≤ 7 g/L) at 25°C using quasielastic light scattering. Spectra are highly bimodal. The two spectral modes (“slow,” “fast”) have different physical properties. Probe behavior differs between small (d < Rh) and large (d ≥ Rg) probes; Rh and Rg are the matrix polymer hydrodynamic radius and the radius of gyration, respectively. We examined the dependences of spectral lineshape parameters on d, c, scattering vector q, and viscosity η for all four probe‐size and mode‐type combinations. We find three time scale‐separated modes: (1) a large‐probe slow mode has properties characteristic of particle motion in a viscous medium; (2) a large‐probe fast mode and small‐probe slow modes share the same time scale, and have properties characteristic of probe motion coupled to internal chain dynamics; and (3) a small‐probe fast mode has properties that can be attributed to the probe sampling local chain relaxations. In the analysis, we also attempted to apply the coupling/scaling (CS) model of Ngai and Phillies [Ngai, K. L., Phillies, G. D. J. J. Chem. Phys., 105, 8385 (1996)] to analyze our data. We find that the second mode is described by the coupling/scaling model for probe diffusion; the first and third modes do not follow the predictions of this model. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 3087–3100, 1998

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Section: Coupling/scaling Analysismentioning

confidence: 70%

Relaxational mode structure for optical probe diffusion in high molecular weight hydroxypropylcellulose

Streletzky

Phillies

1998

J. Polym. Sci. B Polym. Phys.

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“…This crossover property is found also in other many-body relaxation systems besides glass-formers [7,[56][57][58][59][60][61][62], and hence it is a general property. The magnitude of t c depends on the intermolecular potential V (r ).…”

Section: Guides From Experimentsmentioning

confidence: 55%

Guides to solving the glass transition problem

Ngai¹,

Prevosto²,

Capaccioli³

et al. 2008

J. Phys.: Condens. Matter

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Relaxation in glass-forming substances is necessarily a many-body problem because of intermolecular interactions and constraints. Results from molecular dynamics simulations and experiments are used to reveal the critical elements and general effects originating from many-body relaxation, but not dealt with in conventional theories of the glass transition. Although many-body relaxation is still an unsolved problem in statistical mechanics, these critical elements and general effects will serve as guides to the construction of a satisfactory theory of the glass transition. This effort is aided by concepts drawn from the coupling model, whose predictions have been shown to be consistent with experimental facts.

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“…19 Because of its convenient physical properties and wide accessibility HPC has been used extensively in studies of polymer dynamics. 13,15,18,[20][21][22][23] The polymer has numerous pharmaceutical and food industry applications as it is FDA-approved for food and clinical consumption. 24,25 In particular, HPC polymer is used as a tablet binder 26,27 due to its high cohesiveness, binding strength, hardness, and low friability.…”

Section: Introductionmentioning

confidence: 99%

“…References 13,21 Therefore, the usage of cumulants in these systems is not advisable. In addition, refs.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Spectral time moment analysis of microgel deswelling. Effect of the heating rate

Streletzky¹,

McKenna²

2008

J Polym Sci B Polym Phys

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Microgel nanoparticles were synthesized in aqueous solutions of neutral polymer hydroxypropylcellulose (HPC) through the self-association of amphiphilic HPC molecules and the subsequent cross linking at room temperature. Dynamic Light Scattering was used to study the transport properties of HPC microgels below and above the volume phase transition. Highly nonexponential, multimodal microgel spectra were observed and successfully analyzed by spectral time moment analysis. This article expands earlier results and focuses on the effect of the heating rate on microgel deswelling. During the fast heating two identified microgel modes with apparent hydrodynamic radii (R H ) of 25-30 nm and 400-650 nm collapse into one mode with R H = 100−150 nm. This indicates the shrinkage of microgel size distribution and an apparent decrease in the radius of larger microgels. During the slow heating, however, both microgel-identified modes remain present above T c . Although equally represented below the transition, the dominance of larger microgels' mode increases almost two fold with rising temperature above 40• C. Moreover, R H for this mode increases from 250-300 nm to about 800-850 nm with a multi-step temperature change from 40 to 42.5• C, indicating the growth (and not shrinkage) of microgels. The second mode is represented by the temperature independent R H , but its contribution goes down from about 50% to less than 10%.

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Transport in intermediate and high molecular weight hydroxypropylcellulose/water solutions

Cited by 53 publications

References 15 publications

Relaxational mode structure for optical probe diffusion in high molecular weight hydroxypropylcellulose

Relaxational mode structure for optical probe diffusion in high molecular weight hydroxypropylcellulose

Guides to solving the glass transition problem

Spectral time moment analysis of microgel deswelling. Effect of the heating rate

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