Kinetics of high density functional polymer nanocomposite formation by tuning enthalpic and entropic barriers

Abstract

High density functional polymer nanocomposites (PNCs) with high degree of dispersion have recently emerged as novel materials for various thermo-mechanical, optical and electrical applications. The key challenge is to attain...

Microscopic temperature-dependent structural dynamics in polymer nanocomposites: role of the graft–matrix chain interfacial entropic effect

“…14 The dynamics are observed to be dependent on the entropic parameter f and the length scale under investigation. The relaxation time (t KWW ), which was probed using QENS, increases slightly for low-f but decreases significantly for high-f compared with pristine PS, in contrast to earlier observations 13,[15][16][17] on similar systems at a longer length and time scales. The observations are, however, consistent with the graft chain-lengthdependent dispersion and viscosity as proposed by Kumar et al 42,43 In addition, we also observe a wave-vector-dependent dynamical cross-over from Gaussian behavior, at smaller wave vectors, to non-Gaussian behavior at larger wave vectors.…”

“…DPGNPs were synthesized through a grafting-to method as discussed in our earlier reports. 13,17,19 The DPGNPs were characterized well using thermogravimetric analysis (Mettler Toledo), transmission electron microscopy (TEM; Technai G2 F30), small angle X-ray scattering (SAXS; Nanostar, Bruker Germany), and differential scanning calorimetry (DSC; TA instruments) -see ESI † for details 45 . The overall size of the DPGNP (d DPGNP ), as estimated via SAXS, is 6.9 nm (ESI, † Fig.…”

“…Moreover, additional parameters such as the size of the NPs and the width of interfacial layer (IL) have been found to influence the viscoelastic properties of the PNCs. [13][14][15][16][17][18] While the structure and dynamics of pristine polymer melts are largely determined by entropic effects in PNCs, a strong enthalpic effect is introduced between the NP and the matrix chains [17][18][19] that strongly alters their structure and dynamics. With polymer-grafted NPs (PGNPs), which are used widely to enhance the dispersion at high loadings in PNCs, an additional entropic effect is introduced due to size mismatch between the graft and matrix chains, even for chemically identical monomers.…”

Addressing Nanocomposite Systems via 3D-SCFT: Assessment of Smearing Approximation and Irregular Grafting Distributions

“…Polymer-grafted nanoparticles (PGNPs) are quite promising for the manufacturing of membrane − and composite materials − for gas separation, biological, , mechanical reinforcement, − and optical applications . Theoretical frameworks and computer simulations are very useful in guiding and interpreting experimental studies and help resolve major design issues of industrial interest. ,− A variety of theoretical and simulation methodologies have been employed to address systems of PGNPs and brushes, such as the polymer reference interaction site model (PRISM), self-consistent field theory (SCFT), − density functional theory (DFT), − molecular dynamics (MD), − dissipative particle dynamics (DPD), − as well as machine-learning frameworks. , In addition to these studies, scaling laws for the height of the polymer brush have been proposed to describe the structural behavior of grafted chains in the solid/polymer interfacial region over a broad range of experimental conditions. ,− …”

Enhanced efficiency of water desalination in nanostructured thin-film membranes with polymer grafted nanoparticles

“…43 Here, we demonstrate the fabrication of an ultra-selective TFC-PA membrane with remarkable salt rejection performance even at desirably large J w . We achieve this goal by depositing a controlled number, N (1 ≤ N ≤ 7), of PGNP layers on modified TFC-PA membranes using the Langmuir-Blodgett (LB) method [44][45][46] (see Methods section, ESI Fig. S4 †).…”