Densely Packed Tethered Polymer Nanoislands: A Simulation Study

COordinated Responsive Arrays of Surface-Linked polymer islands (CORALS) allow for the creation of molecular surfaces with novel and switchable properties. Critical components of CORALs are the uniformly distributed islands of densely grafted polymer chains (nanoislands) separated by regions of bare surface. The grafting footprint and separation distances of nanoislands are comparable to that of the constituent polymer chains themselves. Herein, we characterize the structural features of the nanoislands and semiflexible polymers within to better understand this critical constituent of CORALs. We observe different characteristics of grafted semiflexible polymers depending on the polymer island’s size and distance from the center of the island. Specifically, the characteristics of the chains at the island periphery are similar to isolated tethered polymer chains (full flexible chains), while chains in the center of the island experience the neighbor effect such as chains in the classic polymer brush. Chains close to the edge of the islands exhibit unique structural features between these two regimes. These results can be used in the rational design of CORALs with specific interfacial characteristics and predictable responses to external stimuli. It is hoped that this the discussion of the different morphologies of the polymers as a function of distance from the edge of the polymer will find applications in a wide variety of systems.

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Oil Deposition on Polymer Brush-Coated NF Membranes

Membranes ◽

10.3390/membranes9120168 ◽

2019 ◽

Vol 9 (12) ◽

pp. 168 ◽

Cited By ~ 1

Author(s):

Anh Vu ◽

Naama Segev Mark ◽

Guy Z. Ramon ◽

Xianghong Qian ◽

Arijit Sengupta ◽

...

Keyword(s):

Membrane Fouling ◽

Membrane Surface ◽

Polymer Brush ◽

Operating Mode ◽

Feed Solution ◽

Polymer Chains ◽

Membrane Properties ◽

Solution Temperature ◽

Oil Droplets ◽

Grafted Polymer

Membrane-based processes are attractive for treating oily wastewaters. However, membrane fouling due to the deposition of oil droplets on the membrane surface compromises performance. Here, real-time observation of the deposition of oil droplets by direct confocal microscopy was conducted. Experiments were conducted in dead-end and crossflow modes. Base NF 270 nanofiltration membranes as well as membranes modified by grafting poly(N-isopropylacrylamide) chains from the membrane surface using atom transfer radical polymerization were investigated. By using feed streams containing low and high NaCl concentrations, the grafted polymer chains could be induced to switch conformation from a hydrated to a dehydrated state, as the lower critical solution temperature for the grafted polymer chains moved above and below the room temperature, respectively. For the modified membrane, it was shown that switching conformation of the grafted polymer chains led to the partial release of adsorbed oil. The results also indicate that, unlike particles such as polystyrene beads, adsorption of oil droplets can lead to coalescence of the adsorbed oil droplets on the membrane surface. The results provide further evidence of the importance of membrane properties, feed solution characteristics, and operating mode and conditions on membrane fouling.

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Rational design of Ag nanoparticle/polymer brush and its application in electroless deposition to fabricate adhesion-enhanced copper pattern for functional flexible electronics

Journal of the Taiwan Institute of Chemical Engineers ◽

10.1016/j.jtice.2021.06.034 ◽

2021 ◽

Author(s):

Ruxia Zhang ◽

Chengmei Gui ◽

Junjun Huang ◽

Guisheng Yang

Keyword(s):

Flexible Electronics ◽

Rational Design ◽

Electroless Deposition ◽

Polymer Brush ◽

Ag Nanoparticle

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Graft Polymers Derived from Natural Rubber

Rubber Chemistry and Technology ◽

10.5254/1.3542530 ◽

1956 ◽

Vol 29 (1) ◽

pp. 99-105 ◽

Cited By ~ 1

Author(s):

G. F. Bloomfield ◽

F. M. Merrett ◽

F. J. Popham ◽

P. Mc L. Swift

Keyword(s):

Tensile Strength ◽

Natural Rubber ◽

Methyl Methacrylate ◽

Transfer Reaction ◽

Polymer Chains ◽

Vinyl Monomers ◽

Grafted Polymer ◽

Polymeric Chains ◽

Graft Polymers ◽

Direct Growth

Abstract Graft polymers result when vinyl monomers are polymerized in the presence of natural rubber, either in solution or as latex, and some of the polymeric chains become attached to the rubber molecules. The properties of the natural rubber can be widely modified according to the nature and the amount of the grafted polymer. The polymer-modified natural rubber appears to be produced by direct growth of polymer chains on to rubber molecules rather than by a transfer reaction involving the rubber. Graft polymers of styrene and methyl methacrylate with natural rubber can be compounded and cured to give light-colored articles of good tensile strength, and rubber-methyl methacrylate graft polymers have outstanding flex-cracking and fatigue resistance.

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It's Not Just Structural: Social Movements are not Homogenous Responses to Structural Features, but Networks shaped by Organisational Strategies and Status

Sociological Research Online ◽

10.5153/sro.1856 ◽

2009 ◽

Vol 14 (1) ◽

pp. 26-41 ◽

Cited By ~ 5

Author(s):

Clare Saunders

Keyword(s):

Structural Features ◽

Political Opportunity ◽

Opportunity Structures ◽

Government Institutions ◽

Political Opportunities ◽

The Status ◽

Political Opportunity Structures ◽

The Uk ◽

Different Characteristics ◽

Environmental Organisation

Political opportunity structures are often used to explain differences in the characteristics of movements in different countries on the basis of the national polity in which they exist. However, the approach has a number of weaknesses that are outlined in this article. The article especially stresses the fact that such broad-brush approaches to political opportunity structures fail to account for the different characteristics of movement organisations within the same polity. The article therefore recommends using a more fine-tuned approach to political opportunities, taking into account that the strategies and status of organisations affect the real political opportunities they face. This fine-tuned approach is used to predict how the status and strategy of environmental organisations might influence the extent to which different types of environmental organisations in the UK network with one-another. We find that organisations that face an open polity - those with a moderate action repertoire and a constructive relationship with government institutions - tend not to cooperate with those with a radical action repertoire and negative relations with government institutions. On the other hand, those that vary their action repertoires, and which have variable status according to the issues involved or campaign targets, have a much broader range of network links with other types of organisations. Thus, there is much more diversity in types of environmental organisation in the UK than the broad-brush to political opportunity structures would account for. Nonetheless, it does seem that environmental organisations are aware of how their own behaviours might influence (non-structural) political opportunities, and that they mould their strategies and networking patterns around this awareness.

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Avian Pattern Recognition Receptor Sensing and Signaling

Veterinary Sciences ◽

10.3390/vetsci7010014 ◽

2020 ◽

Vol 7 (1) ◽

pp. 14 ◽

Cited By ~ 5

Author(s):

Sabari Nath Neerukonda ◽

Upendra Katneni

Keyword(s):

Pattern Recognition ◽

Rational Design ◽

Animal Species ◽

Critical Role ◽

Functional Characterization ◽

Structural Features ◽

Present Review ◽

Vaccine Adjuvants ◽

Microbial Defense ◽

Recognition Receptor

Pattern recognition receptors (PRRs) are a class of immune sensors that play a critical role in detecting and responding to several conserved patterns of microorganisms. As such, they play a major role in the maintenance of immune homeostasis and anti-microbial defense. Fundamental knowledge pertaining to the discovery of PRR functions and their ligands continue to advance the understanding of immune system and disease resistance, which led to the rational design and/or application of various PRR ligands as vaccine adjuvants. In addition, the conserved nature of many PRRs throughout the animal kingdom has enabled the utilization of the comparative genomics approach in PRR identification and the study of evolution, structural features, and functions in many animal species including avian. In the present review, we focused on PRR sensing and signaling functions in the avian species, domestic chicken, mallard, and domestic goose. In addition to summarizing recent advances in the understanding of avian PRR functions, the present review utilized a comparative biology approach to identify additional PRRs, whose functions have been well studied in mammalians but await functional characterization in avian.

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Effect of Structure of Polymers Grafted from Graphene Oxide on the Compatibility of Particles with a Silicone-Based Environment and the Stimuli-Responsive Capabilities of Their Composites

Nanomaterials ◽

10.3390/nano10030591 ◽

2020 ◽

Vol 10 (3) ◽

pp. 591 ◽

Cited By ~ 2

Author(s):

Monika Zygo ◽

Miroslav Mrlik ◽

Marketa Ilcikova ◽

Martina Hrabalikova ◽

Josef Osicka ◽

...

Keyword(s):

Molecular Weight ◽

Graphene Oxide ◽

Radical Polymerization ◽

Polymer Brushes ◽

Silicone Oil ◽

Polymer Chains ◽

Butyl Methacrylate ◽

Raman Shift ◽

Stimuli Responsive ◽

Grafted Polymer

This study reports the utilization of controlled radical polymerization as a tool for controlling the stimuli-responsive capabilities of graphene oxide (GO) based hybrid systems. Various polymer brushes with controlled molecular weight and narrow molecular weight distribution were grafted from the GO surface by surface-initiated atom transfer radical polymerization (SI-ATRP). The modification of GO with poly(n-butyl methacrylate) (PBMA), poly(glycidyl methacrylate) (PGMA), poly(trimethylsilyloxyethyl methacrylate) (PHEMATMS) and poly(methyl methacrylate) (PMMA) was confirmed by thermogravimetric analysis (TGA) coupled with online Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Various grafting densities of GO-based materials were investigated, and conductivity was elucidated using a four-point probe method. Raman shift and XPS were used to confirm the reduction of surface properties of the GO particles during SI-ATRP. The contact angle measurements indicated the changes in the compatibility of GOs with silicone oil, depending on the structure of the grafted polymer chains. The compatibility of the GOs with poly(dimethylsiloxane) was also investigated using steady shear rheology. The tunability of the electrorheological, as well as the photo-actuation capability, was investigated. It was shown that in addition to the modification of conductivity, the dipole moment of the pendant groups of the grafted polymer chains also plays an important role in the electrorheological (ER) performance. The compatibility of the particles with the polymer matrix, and thus proper particles dispersibility, is the most important factor for the photo-actuation efficiency. The plasticizing effect of the GO-polymer hybrid filler also has a crucial impact on the matrix stiffness and thus the ability to reversibly respond to the external light stimulation.

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