Compatibilizing Immiscible Polymer Blends with Sparsely Grafted Nanoparticles

Alkhodairi, Husam; Russell, Sebastian T.; Pribyl, Julia; Benicewicz, Brian C.; Kumar, Sanat K.

doi:10.1021/acs.macromol.0c02108

Cited by 40 publications

(31 citation statements)

References 70 publications

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“…Figure shows morphology predictions as a function of an overcrowding parameter, X , as a function of the ratio of the matrix ( P ) to graft chain length ( N ). This plot is from the work of Alkhodairi et al based on previous works by Kumar et al and Akcora et al , The parameter X is based on the theoretical ideas of Midya et al who proposed a two-layer model where a densely grafted polymer brush (corona) was divided into “dry” and “interpenetrated brush” zones with heights of h dry and h inter , respectively. The interpenetrated zone consists of a significant overlap between grafted layers of surrounding nanoparticles and the matrix, while the chain fragments in the dry zone are so stretched that they do not interact with any chains that do not “belong” to the same polymer-grafted nanoparticles.…”

Section: Resultsmentioning

confidence: 99%

Using Nanofiller Assemblies to Control the Crystallization Kinetics of High-Density Polyethylene

et al. 2021

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Polyethylene-grafted nanoparticles (NPs) are organized into a variety of assemblies in a polydisperse polyethylene melt by tailoring the graft density and molecular weights of the graft chains. Under these conditions, we systematically vary the NP assemble state and study its consequences on crystal nucleation and growth rates. We find that the nucleation rate is suppressed below that of the unfilled polymer for good NP spatial dispersion. However, poorer dispersion, which leads to the formation of NP assemblies, can accelerate nucleation likely by providing multiple heterogeneous sites due to topographical features. We find that a key parameter, the chain overcrowding in the brush, can predict these nucleation trends; in this language, the most enhanced nucleation rate is found when the grafts are the most overcrowded and, hence, the least interpenetrated with the matrix chains. This result is consistent with one other literature result that utilized short crystallizable polyethylene glycol grafts in short polyethylene oxide (PEO) matrices. The growth kinetics were retarded for all nanocomposites, and their temperature dependences were essentially equal to that for the pure polymer (in the absence of NPs); the NPs thus do not affect secondary nucleation, indicating that the transport of the matrix to the growth front is the rate-determining step. Thus, evidently, the increase in matrix viscosity, or reduction in growth rates, is directly determined by the agglomeration state of the NPs. These results are consistent with past works with bare silica NPs in PEO and with silica NPs grafted with amorphous chains in a PEO matrix, suggesting that growth kinetics in these systems apparently follow “universal” behavior. Additionally, there are initial hints that the ratio of the effective surface area of the NP clusters per unit matrix volume provides a unified description of the NP-induced confinement that slows growth kinetics. Our work thus shows that there is an evolving understanding of the role of NPs in crystallization kinetics, in particular, crystal growth where trends appear to be independent of the grafts’ ability to crystallize.

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Section: Resultsmentioning

confidence: 99%

Using Nanofiller Assemblies to Control the Crystallization Kinetics of High-Density Polyethylene

et al. 2021

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“…Grafting polymer chains onto a nanoparticle is a typical strategy to promote miscibility and homogeneity in nanocomposites. − Grafted nanoparticles (GNPs) comprise a hard inorganic (hydrophilic) core and an organic (polymeric) shell; their surfactant-like structure makes them attractive as hybrid building blocks for hierarchical assemblies and functional materials . The presence of grafted chains prevents nanoparticle aggregation, although this strongly depends on the surface coverage.…”

Section: Introductionmentioning

confidence: 99%

“…Most often, GNPs are dispersed in a matrix of polymer chains or oligomers having the same chemistry as the grafted chains. Several theoretical, experimental, and computational approaches have been used in the last 30 years to investigate the structural properties and dynamics of these systems. − …”

Section: Introductionmentioning

confidence: 99%

Universal Polymeric-to-Colloidal Transition in Melts of Hairy Nanoparticles

et al. 2021

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Two different classes of hairy self-suspended nanoparticles in the melt state, polymer-grafted nanoparticles (GNPs) and star polymers, are shown to display universal dynamic behavior across a broad range of parameter space. Linear viscoelastic measurements on well-characterized silica-poly(methyl acrylate) GNPs with a fixed core radius (R core) and grafting density (or number of arms f) but varying arm degree of polymerization (N arm) show two distinctly different regimes of response. The colloidal Regime I with a small N arm (large core volume fraction) is characterized by predominant low-frequency solidlike colloidal plateau and ultraslow relaxation, while the polymeric Regime II with a large N arm (small core volume fractions) has a response dominated by the starlike relaxation of partially interpenetrated arms. The transition between the two regimes is marked by a crossover where both polymeric and colloidal modes are discerned albeit without a distinct colloidal plateau. Similarly, polybutadiene multiarm stars also exhibit the colloidal response of Regime I at very large f and small N arm. The star arm retraction model and a simple scaling model of nanoparticle escape from the cage of neighbors by overcoming a hopping potential barrier due to their elastic deformation quantitatively describe the linear response of the polymeric and colloidal regimes, respectively, in all these cases. The dynamic behavior of hairy nanoparticles of different chemistry and molecular characteristics, investigated here and reported in the literature, can be mapped onto a universal dynamic diagram of f/[R core 3/ν0)1/4] as a function of (N armν0 f)/(R core 3), where ν0 is the monomeric volume. In this diagram, the two regimes are separated by a line where the hopping potential ΔU hop is equal to the thermal energy, k B T. ΔU hop can be expressed as a function of the overcrowding parameter x (i.e., the ratio of f to the maximum number of unperturbed chains with N arm that can fill the volume occupied by the polymeric corona); hence, this crossing is shown to occur when x = 1. For x > 1, we have colloidal Regime I with an overcrowded volume, stretched arms, and ΔU hop > k B T, while polymeric Regime II is linked to x < 1. This single-material parameter x can provide the needed design principle to tailor the dynamics of this class of soft materials across a wide range of applications from membranes for gas separation to energy storage.

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“…The second blending mechanism assumes that the two polymeric materials do not dissolve in each other and form the interface between components. This mechanism is referred to as immiscible blending [20,53,[139][140][141][142]. Finally, the third mechanism implies that one polymeric material partially dissolves into another polymeric material during the heterogeneous phase.…”

Section: Polyphenylsulfone Blended With the Polymermentioning

confidence: 99%

Recent Advancements in Polyphenylsulfone Membrane Modification Methods for Separation Applications

2022

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Polyphenylsulfone (PPSU) membranes are of fundamental importance for many applications such as water treatment, gas separation, energy, electronics, and biomedicine, due to their low cost, controlled crystallinity, chemical, thermal, and mechanical stability. Numerous research studies have shown that modifying surface properties of PPSU membranes influences their stability and functionality. Therefore, the modification of the PPSU membrane surface is a pressing issue for both research and industrial communities. In this review, various surface modification methods and processes along with their mechanisms and performance are considered starting from 2002. There are three main approaches to the modification of PPSU membranes. The first one is bulk modifications, and it includes functional groups inclusion via sulfonation, amination, and chloromethylation. The second is blending with polymer (for instance, blending nanomaterials and biopolymers). Finally, the third one deals with physical and chemical surface modifications. Obviously, each method has its own limitations and advantages that are outlined below. Generally speaking, modified PPSU membranes demonstrate improved physical and chemical properties and enhanced performance. The advancements in PPSU modification have opened the door for the advance of membrane technology and multiple prospective applications.

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Compatibilizing Immiscible Polymer Blends with Sparsely Grafted Nanoparticles

Cited by 40 publications

References 70 publications

Using Nanofiller Assemblies to Control the Crystallization Kinetics of High-Density Polyethylene

Using Nanofiller Assemblies to Control the Crystallization Kinetics of High-Density Polyethylene

Universal Polymeric-to-Colloidal Transition in Melts of Hairy Nanoparticles

Recent Advancements in Polyphenylsulfone Membrane Modification Methods for Separation Applications

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