Polymers in 2-D confinement

Frielinghaus, Henrich; Frielinghaus, Xiuli; Ruocco, Nino; Allgaier, Jürgen; Pyckhout‐Hintzen, Wim; Richter, Dieter

doi:10.1039/c3sm50644d

Cited by 9 publications

(11 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results have shown that the degree of nanoconfinement influences the structure–property correlation of layered silicate/polyelectrolyte nanocomposites, especially for intercalated polymers which can experience different degree of intercalation, as described by Morgan and Gilman . Polymer size and gallery spacing define different confinement regimes, as described theoretically by de Gennes and supported by these and other experimental results …”

Section: Resultssupporting

confidence: 74%

See 1 more Smart Citation

Viscoelasticity and Dynamics of Confined Polyelectrolyte/Layered Silicate Nanocomposites: The Influence of Intercalation and Exfoliation

Romo-Uribe

Cardoso

2017

Macro Chemistry & Physics

View full text Add to dashboard Cite

The influence of different confinement regimes on the linear viscoelastic properties of a polyelectrolyte, the protonated poly‐[(dimethylamino) ethyl methacrylate] (PDMAEMAH), is investigated. PDMAEMAH is reinforced with the layered silicate montmorillonite (MMT). Neat MMT and MMT treated with sulfobetaine and ammonia‐based surfactants (MMT/SB and MMT/NH, respectively) are utilized. Transmission electron microscopy and X‐ray scattering show that MMT and MMT/NH produce intercalated morphology, whereas MMT/SB produces an exfoliated morphology. Thus, the polyelectrolyte is under different confinement regimes. The confinement produces the increase of glass transition temperature Tg; however, the increase is larger for the (highly confined) intercalated morphology. Master curves are constructed applying time–temperature superposition. Strikingly, the viscoelastic spectra evidence that the intercalated morphology produces twofold increase of rubber‐like modulus, whereas the exfoliated morphology produces over fourfold reduction of rubber‐like modulus, both at 3 wt% clay concentration. The reduction of rubber‐like modulus suggests that an exfoliated morphology produces disruption of the entanglement density. Analysis in the segmental relaxation regime shows that the intercalated morphology induces longer relaxation times, that is, more dynamics retardation, in correlation with the increase of glass transition temperature. This research paves the road for better understanding of viscoelastic behavior and dynamics of molten polyelectrolytes under confinement.

show abstract

Section: Resultssupporting

confidence: 74%

“…[55] Polymer size and gallery spacing define different confinement regimes, as described theoretically by de Gennes [34] and supported by these and other experimental results. [25,56]…”

Section: Linear Viscoelastic Behaviormentioning

confidence: 99%

Viscoelasticity and Dynamics of Confined Polyelectrolyte/Layered Silicate Nanocomposites: The Influence of Intercalation and Exfoliation

Romo-Uribe

Cardoso

2017

Macro Chemistry & Physics

View full text Add to dashboard Cite

show abstract

“…In view of these results, it is suggested that disparate, sometimes contradictory, results reported for some polymer‐clay nanocomposites would need to be revised in terms of the degree of nanoconfinement, especially as intercalated polymers experience different degree of intercalation, as described by Morgan and Gilman . Polymer size and gallery spacing define different confinement regimes, as described theoretically by de Gennes and supported by experimental results …”

Section: Resultsmentioning

confidence: 82%

“…32 Polymer size and gallery spacing define different confinement regimes, as described theoretically by de Gennes 33 and supported by experimental results. 34…”

Section: (A) (B)mentioning

confidence: 99%

Polymers in 2D confinement: A nanoscale mechanism for thermo‐mechanical reinforcement

Romo-Uribe

2017

Polymers for Advanced Techs

View full text Add to dashboard Cite

Acrylate-clay nanocomposites, a 2D confined system, exhibited unusual increase of thermo-mechanical properties. The nature of this reinforcement can be ascribed to chain dynamics modification and therefore investigated via dynamic mechanical analysis. Transmission electron microscopy and dynamic light scattering showed a strong nanoconfined regime, 2R h ≫ d 001 , where R h is the polymer's hydrodynamic radius and d 001 is the clay gallery spacing.The geometrical constraints to polymer dynamics led to significant enhancement of the thermo-mechanical properties. Adding only 1 wt% nanoclay, the glass transition temperature increased significantly, ΔT g = T g − T g,bulk~1 0°C, and the dynamic modulus E′ increased 10-fold.Analysis of dynamic mechanical spectra showed an increase of relaxation time τ, ie, polymer dynamics retardation. Furthermore, the mechanical damping tan δ was strongly attenuated evidencing the reduction of viscous dissipation. The activation energy E a of the α-transition increased as the confined macromolecules needed to overcome higher energy barriers to achieve configurational rearrangements. The considerable increase of mechanical modulus cannot be explained by polymer composite models, rather it was associated to a "nano-effect," scaling with the degree of confinement as E/E matrix~( 2R h /d 001 )n . This study paves the road for further understanding of polymer dynamics under 2D confinement and the reinforcement mechanism of thermo-mechanical properties. 1-3 Hybrid nanoparticles are also successful to produce nanocomposites with more robust physical properties and are also being used to produce smart, shape memory polymeric networks with tailored thermo-mechanical properties. 4,5The addition of nanoclays, ie, layered silicates, to glassy and semicrystalline polymers has produced nanocomposites with enhanced mechanical, thermal, and barrier properties. For recent reviews, see Paul and Robeson 3 and Ray and Okamoto. 6 It is noted however that polymers (glassy and semicrystalline) with nanoclay concentrations in excess of 10 wt% led to relatively modest enhancement of mechanical properties, and the degree of property enhancement varies broadly according to the type of nanoclay used and the surface treatment. Furthermore, the concentration of nanoclays used also varies greatly and higher concentrations (>10%) appear contrary to the assumption that rather small concentrations of nanofiller would enhance the physical properties. 2,3It is believed that the macromolecular nanoconfinement found in, for instance, intercalated morphologies of layered silicate nanocomposites would be responsible to a larger extent for the changes of thermomechanical properties. For instance, confinement has induced lowering or increasing of the glass transition temperature, T g , in glassy polymer nanocomposites. The reduction of T g in confined small molecule glassy materials was first documented by McKenna et al. 7 The confinement in polymer nanocomposites is understood as (1) polymer chains constrained to layere...

show abstract

“…Furthermore, two-dimensional confinement in closed flat spaces can result in a order-disorder shape transition [34] similar to that of SW. One advantage of confinement in the flat twodimensional case is that it can be compared with the experiment [42,55,27,19]. However, in the literature as far as we know, even in the semiflexible ideal chain there is not a systematic study of the SW transition in a flat and bounded region.…”

Section: Introductionmentioning

confidence: 99%

Stochastic curvature of enclosed semiflexible polymers

Castro-Villarreal

Ramírez

2019

Phys. Rev. E

View full text Add to dashboard Cite

The conformational states of a semiflexible polymer enclosed in a compact domain of typical size a are studied as stochastic realizations of paths defined by the Frenet equations under the assumption that stochastic "curvature" satisfies a white noise fluctuation theorem. This approach allows us to derive the Hermans-Ullman equation, where we exploit a multipolar decomposition that allows us to show that the positional probability density function is well described by a Telegrapher's equation whenever 2a/ p > 1, where p is the persistence length. We also develop a Monte Carlo algorithm for use in computer simulations in order to study the conformational states in a compact domain. In addition, the case of a semiflexible polymer enclosed in a square domain of side a is presented as an explicit example of the formulated theory and algorithm. In this case, we show the existence of a polymer shape transition similar to the one found by Spakowitz and Wang [Phys. Rev. Lett. 91, 2 (2003)] where in this case the critical persistence length is * p a/8 such that the mean-square end-to-end distance exhibits an oscillating behavior for values p >

show abstract

Polymers in 2-D confinement

Cited by 9 publications

References 33 publications

Viscoelasticity and Dynamics of Confined Polyelectrolyte/Layered Silicate Nanocomposites: The Influence of Intercalation and Exfoliation

Viscoelasticity and Dynamics of Confined Polyelectrolyte/Layered Silicate Nanocomposites: The Influence of Intercalation and Exfoliation

Polymers in 2D confinement: A nanoscale mechanism for thermo‐mechanical reinforcement

Stochastic curvature of enclosed semiflexible polymers

Contact Info

Product

Resources

About