Estimating diffusion coefficients for small molecules in polymers and polymer solutions

Karlsson, Ola; Stubbs, Jeffrey M.; Karlsson, Lina; Sundberg, Donald C.

doi:10.1016/s0032-3861(00)00765-5

Cited by 77 publications

(68 citation statements)

References 19 publications

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“…The composition at which the system turns into a glass according to this interpretation differs from the composition where the water diffusivity shows a rapid change. This behavior, also observed in non-aqueous polymer systems, can be explained in terms of the different properties being investigated (Faldi et al, 1994;Tonge and Gilbert, 2001;Karlsson et al, 2001). D w (T , a w ) represents a property that describes a rate of transport and ultimately ln [D w The molar mass of SOM is assumed to be 150 g for this parameterization.…”

Section: A2 Parameterization Of D W (T a W )mentioning

confidence: 76%

Viscous organic aerosol particles in the upper troposphere: diffusivity-controlled water uptake and ice nucleation?

Lienhard

Huisman

Krieger³

et al. 2015

Atmos. Chem. Phys.

119

193

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Abstract. New measurements of water diffusion in secondary organic aerosol (SOA) material produced by oxidation of α-pinene and in a number of organic/inorganic model mixtures (3-methylbutane-1,2,3-tricarboxylic acid (3-MBTCA), levoglucosan, levoglucosan/NH 4 HSO 4 , raffinose) are presented. These indicate that water diffusion coefficients are determined by several properties of the aerosol substance and cannot be inferred from the glass transition temperature or bouncing properties. Our results suggest that water diffusion in SOA particles is faster than often assumed and imposes no significant kinetic limitation on water uptake and release at temperatures above 220 K. The fast diffusion of water suggests that heterogeneous ice nucleation on a glassy core is very unlikely in these systems. At temperatures below 220 K, model simulations of SOA particles suggest that heterogeneous ice nucleation may occur in the immersion mode on glassy cores which remain embedded in a liquid shell when experiencing fast updraft velocities. The particles absorb significant quantities of water during these updrafts which plasticize their outer layers such that these layers equilibrate readily with the gas phase humidity before the homogeneous ice nucleation threshold is reached. Glass formation is thus unlikely to restrict homogeneous ice nucleation. Only under most extreme conditions near the very high tropical tropopause may the homogeneous ice nucleation rate coefficient be reduced as a consequence of slow condensed-phase water diffusion. Since the differences between the behavior limited or non limited by diffusion are small even at the very high tropical tropopause, condensed-phase water diffusivity is unlikely to have significant consequences on the direct climatic effects of SOA particles under tropospheric conditions.

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Section: A2 Parameterization Of D W (T a W )mentioning

confidence: 76%

Viscous organic aerosol particles in the upper troposphere: diffusivity-controlled water uptake and ice nucleation?

Lienhard

Huisman

Krieger³

et al. 2015

Atmos. Chem. Phys.

119

193

View full text Add to dashboard Cite

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“…Clearly, the present model performs much better for MMA systems than for styrene. Our analysis suggests that this may be due to some inaccuracies in the method used to estimate diffusion coefficients, [56] which is based on a semi-empirical method developed using PMMA as a model system to estimate monomer diffusion coefficients and poly(butyl methacrylate) (PBMA) as a model for the chain length dependence [57,58] for radical diffusion coefficients. It is known that the entanglement length for polystyrene is significantly longer than for PMMA and other methacrylates [59] and this delays the onset and magnitude of the gel effect.…”

Section: Kinetic Predictionsmentioning

confidence: 99%

“…The diffusion coefficient of radical chain i is dependent on the number of monomer repeat units in the chain and the conditions (temperature, T g , monomer concentration) prevalent during the polymerization, as described in detail previously. [15,56] The location of radical i is updated and then the reaction event occurs. Any new species that are created (for example through chain transfer) are placed at new location of radical i.…”

Section: Note Fmentioning

confidence: 99%

Monte Carlo Simulation of Emulsion Polymerization Kinetics and the Evolution of Latex Particle Morphology and Polymer Chain Architecture

Stubbs

Carrier

Sundberg

2008

Macro Theory & Simulations

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Monte Carlo methods were applied to the reaction kinetics and polymer diffusion at play during the dynamics of creating structured latex particles. Reaction kinetic events in both the water phase and the particles are combined with diffusion of polymer radicals in the particles to allow the prediction of the overall polymerization kinetics, including the Trommsdorf gel effect, chain transfer reactions to monomer, chain transfer agents (e.g., thiols) and polymer chains, and chain length dependent termination reactions. This allowed the calculation of latex particle morphology, as well as the polymer molecular weight, gel content and graft level, when applicable. A number of examples are used to provide experimental data with which to compare the Monte Carlo predictions.magnified image

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“…No experimental attempts have been made to measure the AF diffusion coefficient either in the core or in the shell of the coating but it is well known that diffusion coefficients of small molecules in polymeric matrixes change by several orders of magnitudes with the T g of the polymer. 26 Our initial goal was to change independently the T g of the core and of the shell; however, latexes with high shell T g (such as 1 in Table IV) do not form continuous films upon application at room temperature. All the other latexes have shell T g slightly below room temperature, to allow for the formation of a continuous film at room temperature (MFFT around 208C).…”

Section: Release Of Seanine 211 From the Coatingmentioning

confidence: 99%

“…Using the empirical relationships derived by Sundberg et al in Ref. 26, one can calculate the diffusion coefficient at 258C of SeaNine 211 in a polymer (Wt AF 5 10%). If the T g of the core polymer is 1258C, then the calculated diffusion coefficient of AF in the core is found to be around 1.2 3 10 215 cm 2 /s.…”

Section: Release Of Seanine 211 From the Coatingmentioning

confidence: 99%

Transparent antifouling coatings via nanoencapsulation of a biocide

Zhang

Cabane

Claverie

2007

J of Applied Polymer Sci

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Transparent coatings releasing an antifouling agent (AF) can be used to reduce the marine fouling of optical lenses. A variety of water-borne coatings based on poly(methyl methacrylate-co-butyl acrylate) (PMMAco-PBA) were synthesized using a two-stage miniemulsion process. During this process, the AF, SeaNine 211, was nanoencapsulated in domains small enough not to scatter light. The release rate of SeaNine 211 was studied for the polymers of different T g , and found to be sufficient to impart AF properties. However, over time, the coatings were found to develop a whitish aspect (blushing) due to water retrodiffusion.

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Estimating diffusion coefficients for small molecules in polymers and polymer solutions

Cited by 77 publications

References 19 publications

Viscous organic aerosol particles in the upper troposphere: diffusivity-controlled water uptake and ice nucleation?

Viscous organic aerosol particles in the upper troposphere: diffusivity-controlled water uptake and ice nucleation?

Monte Carlo Simulation of Emulsion Polymerization Kinetics and the Evolution of Latex Particle Morphology and Polymer Chain Architecture

Transparent antifouling coatings via nanoencapsulation of a biocide

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