<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Bachhar, Nirmalya</style></author><author><style face="normal" font="default" size="100%">Kurnaraswamy, Guruswamy</style></author><author><style face="normal" font="default" size="100%">Kumar, Sanat K.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Core-size dispersity dominates the self-assembly of polymer grafted nanoparticles in solution</style></title><secondary-title><style face="normal" font="default" size="100%">Macromolecules</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2019</style></year><pub-dates><date><style  face="normal" font="default" size="100%">JUL </style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">52</style></volume><pages><style face="normal" font="default" size="100%">4888-4894</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;In polymer-grafted nanoparticles (PGN), covalent tethering of apolar polymer chains to a polar inorganic nanoparticle core induces the formation of self-assembled aggregates. Since the nature of these aggregates determines bulk mechanical and transport properties, it is of importance to understand the factors that determine the underlying assembly processes. In the literature, the solution assembly of PGNs has been understood in analogy to small-molecule amphiphiles. However, in any experimental realization, PGNs are invariably characterized by additional structural complexity, such as the distributions in the inorganic core size and in the grafted chains (both in their length and grafting density). These strongly influence the assembly of amphiphilic PGNs. We have previously demonstrated that dispersity in core size qualitatively affects the structure of PGN aggregates, and Jayaraman et al. demonstrated the effect of grafted chain-length dispersity. The combined effects of dispersity in the size of the core and grafted chains have not been explored previously. Here, we develop a model that builds on the work of Daoud and Cotton to explore a wide parameter space of PGN with dispersity simultaneously in core size and grafted chain length. We demonstrate that dispersity in core size is the dominant factor affecting the self-assembled solution structure of PGN aggregates. Our work suggests the importance of focusing on synthetic strategies for control of core-size dispersity to control aggregate structure in PGN.&lt;/p&gt;
</style></abstract><issue><style face="normal" font="default" size="100%">13</style></issue><work-type><style face="normal" font="default" size="100%">Article</style></work-type><custom3><style face="normal" font="default" size="100%">&lt;p&gt;Foreign&lt;/p&gt;
</style></custom3><custom4><style face="normal" font="default" size="100%">&lt;p&gt;4.784&lt;/p&gt;
</style></custom4></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Suresh, Karthika</style></author><author><style face="normal" font="default" size="100%">Chowdhury, Arindam</style></author><author><style face="normal" font="default" size="100%">Kumar, Sanat K.</style></author><author><style face="normal" font="default" size="100%">Kumaraswamy, Guruswamy</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Critical role of processing on the mechanical properties of cross-linked highly loaded nanocomposites </style></title><secondary-title><style face="normal" font="default" size="100%">Macromolecules</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2019</style></year></dates><volume><style face="normal" font="default" size="100%">52</style></volume><pages><style face="normal" font="default" size="100%">5955-5962</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Polymer &lt;span class=&quot;hitHilite&quot;&gt;nanocomposites&lt;/span&gt; are frequently not at equilibrium-therefore, &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; structure and &lt;span class=&quot;hitHilite&quot;&gt;properties&lt;/span&gt; critically depend &lt;span class=&quot;hitHilite&quot;&gt;on&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; protocol followed in their preparation. Here, we demonstrate that &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; elastic-brittle transition in &lt;span class=&quot;hitHilite&quot;&gt;highly&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;loaded&lt;/span&gt; ice-templated polymer &lt;span class=&quot;hitHilite&quot;&gt;nanocomposites&lt;/span&gt; is sensitively determined by &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; conformation &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; polymer chains during nanocomposite preparation. Macroporous polymer &lt;span class=&quot;hitHilite&quot;&gt;nanocomposites&lt;/span&gt; are synthesized using two preparation pathways, both exhibiting minor modifications &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; ice-templating method wherein an aqueous dispersion &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; nanoparticles, polymers, and cross-linkers is frozen. In one method, &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; matrix polymer is &lt;span class=&quot;hitHilite&quot;&gt;cross-linked&lt;/span&gt; in &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; presence &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; ice, whereas in &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; other method, &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; ice is removed by freeze-drying before &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; polymer is &lt;span class=&quot;hitHilite&quot;&gt;cross-linked&lt;/span&gt;. Although all measurable structural metrics are practically identical for &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; two composites, they exhibit qualitatively different &lt;span class=&quot;hitHilite&quot;&gt;mechanical&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;properties&lt;/span&gt;. &lt;span class=&quot;hitHilite&quot;&gt;Nanocomposites&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;cross-linked&lt;/span&gt; in &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; presence &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; ice show exceptional resilience, recovering elastically from large compression for very high nanoparticle loadings-in some instances, above 90% by weight. Here, &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;critical&lt;/span&gt; particle loading for &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; elastic- brittle transition is dependent &lt;span class=&quot;hitHilite&quot;&gt;on&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; molecular weight &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; polymer. In comparison, samples &lt;span class=&quot;hitHilite&quot;&gt;cross-linked&lt;/span&gt; after freeze-drying appear structurally identical but turn brittle at much lower particle loadings (about 60% by weight), independent &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; matrix polymer molecular weight. We rationalize these differences in terms &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; conformational state &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; polymer during cross- linking. In &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; former case, polymer chains are in good solvent during nanocomposite preparation, while after lyophilization, they are in a poor solvent. &lt;span class=&quot;hitHilite&quot;&gt;The&lt;/span&gt; large spatial extent &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; well-solvated chains and chain-chain overlap during cross-linking results in &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; formation &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; intermolecular cross-links, and we obtain elastic &lt;span class=&quot;hitHilite&quot;&gt;nanocomposites&lt;/span&gt; even at high nanoparticle loadings. In contrast, for chains in collapsed conformations in a bad solvent, chain connectivity during cross-linking is achieved only for much lower particle loadings. Our results reiterate that &lt;span class=&quot;hitHilite&quot;&gt;the&lt;/span&gt; sensitivity &lt;span class=&quot;hitHilite&quot;&gt;of&lt;/span&gt; polymer conformations to different &lt;span class=&quot;hitHilite&quot;&gt;processing&lt;/span&gt; methods can result in large differences in &lt;span class=&quot;hitHilite&quot;&gt;properties&lt;/span&gt;, even though their consequences &lt;span class=&quot;hitHilite&quot;&gt;on&lt;/span&gt; structural characteristics are effectively indistinguishable.&lt;/p&gt;
</style></abstract><issue><style face="normal" font="default" size="100%">15</style></issue><work-type><style face="normal" font="default" size="100%">Article</style></work-type><custom3><style face="normal" font="default" size="100%">&lt;p&gt;Foreign&lt;/p&gt;
</style></custom3><custom4><style face="normal" font="default" size="100%">&lt;p&gt;&lt;span class=&quot;jhHeader_impact&quot;&gt;5.997&lt;/span&gt;&lt;/p&gt;
</style></custom4></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Biswas, Bipul</style></author><author><style face="normal" font="default" size="100%">Misra, Mayank</style></author><author><style face="normal" font="default" size="100%">Bisht, Anil Singh</style></author><author><style face="normal" font="default" size="100%">Kumar, Sanat K.</style></author><author><style face="normal" font="default" size="100%">Kumaraswamy, Guruswamy</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Colloidal assembly by directional ice templating</style></title><secondary-title><style face="normal" font="default" size="100%">Soft Matter </style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2021</style></year><pub-dates><date><style  face="normal" font="default" size="100%">APR </style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">17</style></volume><pages><style face="normal" font="default" size="100%">4098-4108</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;We investigate directional ice templating of dilute aqueous colloidal particle dispersions and examine the nature of the assemblies that result. We coat micron-size polystyrene colloids with cross-linkable polymer (polyethyleneimine, PEI), add cross-linker, and subject this dispersion to unidirectional freezing. We work at sufficiently low colloid concentrations, such that the particles do not percolate on freezing. When the aqueous dispersion freezes, ice crystals force polymer-coated particles and cross-linker into close proximity. This results in the formation of cross-linked clusters of particles at ice crystal boundaries. We vary the particle volume fraction from phi similar to 2.5 x 10(-3) to phi similar to 5.0 x 10(-2) and observe that there is a transition from isolated single particles to increasingly large sized clusters. Most of the clusters formed under these conditions are either linear, two-particle wide chains, or sheet-like aggregates. The probability (P-n) of clusters containing n particles (n &amp;gt; 2) obeys a power law P-n similar to n(-eta), where eta strongly depends on the particle concentration in the dispersion, varying from 2.10 (for phi similar to 5.0 x 10(-2)) to 3.03 (for phi similar to 2.5 x 10(-3)). This change in eta is qualitatively different from the case of isotropic freezing, where eta is particle concentration-independent and depends only on the ice nucleation density. To understand the differences between isotropic and directional ice templating, we performed lattice simulations of a highly simplified model, where ice crystals grow at a constant rate to force clustering. We ignore hydrodynamic interactions and ice growth instabilities. Despite ignoring these experimental details, the simulations capture the experimental results, nearly quantitatively. As the ice crystals grow and the space available to the colloids ``closes up'' so that the particles cluster to form aggregates, crystallization protocol-induced differences in the geometry of these ``closed up'' spaces determine the scaling behaviour of P-n.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">15</style></issue><work-type><style face="normal" font="default" size="100%">Article</style></work-type><custom3><style face="normal" font="default" size="100%">&lt;p&gt;Foreign&lt;/p&gt;</style></custom3><custom4><style face="normal" font="default" size="100%">3.679</style></custom4></record></records></xml>