Experimental study of molecular entanglement in polymer networks

Gent, A. N.; Liu, G. L.; Mazurek, M.

doi:10.1002/polb.1994.090320208

Cited by 25 publications

(7 citation statements)

References 17 publications

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“…In addition, the oil-releasing kinetics of SLUG-II was much slower than that of SLUG-I. This was probably due to the strong inter/intraentanglement of the polymer chains of silicone oils and the polymer networks . The polymer chain of silicone oil is reported to preferentially entangle the polymer networks when the MWs of L-PDMSs exceed 21–33k (corresponding to the viscosity over 500–1000 m/Pa·s).…”

Section: Resultsmentioning

confidence: 57%

Transparent Organogel Films Showing Extremely Efficient and Durable Anti-Icing Performance

Urata

Nagashima

Hatton

et al. 2021

ACS Appl. Mater. Interfaces

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Accumulation of ice and snow on solid surfaces causes destructive problems in our daily life. Therefore, the development of functional coatings/surfaces that can effectively prevent ice/snow adhesion by natural forces, such as airflow, vibration, solar radiation, or gravity, is in high demand. In this study, transparent organogel films possessing negligible ice adhesion strength were successfully designed by a simple crosslinking of poly(dimethylsiloxane) (PDMS) in the presence of commercially available oils. Both the molecular weights (MWs) of the infusing oils and their contents in the PDMS matrices have proven to be key parameters for primarily determining the crosslinking density of PDMS matrices and syneresis/nonsyneresis behaviors of our samples, which closely reflected the final surface static/dynamic dewetting and anti-icing properties. By tuning only these two parameters, three different types of transparent organogel films, that is, nonsyneresis organogel (NSG), self-lubricating organogel (SLUG-I, infused with highly mobile oils), and SLUG-II (infused with viscous oils) films, were prepared. Among them, on the SLUG-I films, the lubricating oils were found to be continuously released from the PDMS matrices through syneresis for more than 1 year. Due to this unusual syneresis behavior, the ice adhesion strength became virtually zero, and this excellent anti-icing property also remained almost unchanged even after several cycles of icing/deicing testing. On the other hand, in the case of SLUG-II films, as the lubricated oil layers were too viscous, ice had trouble sliding off the surfaces by gravity. In contrast to these SLUG films, ice adhesion strength on NSG films was markedly decreased by increasing the amount of the infusing oils. In spite of NSG films having no distinct mobile oil layer, the ice adhesion strength reached its minimum of only about 5 kPa.

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Section: Resultsmentioning

confidence: 57%

Transparent Organogel Films Showing Extremely Efficient and Durable Anti-Icing Performance

Urata

Nagashima

Hatton

et al. 2021

ACS Appl. Mater. Interfaces

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“…2,3 These siloxanes, having free radically polymerizable end groups, proved to be of great practical and theoretical interest. 4,5 Due to the polar nature of the hydrogen bonding end groups and the nonpolar nature of the polydimethylsiloxane chain, a transient network is formed wherein the polar end groups tend to associate with each other. The relative strength of the end group association for the various telechelic siloxanes is reflected in their viscosities, with higher viscosities seen in the case of the more strongly associating end groups (e.g., ACMAS and MeStUS).…”

Section: Introductionmentioning

confidence: 99%

“…Functional siloxanes with molecular weights in the range of 5000 to 100,000 have been prepared and studied 2, 3. These siloxanes, having free radically polymerizable end groups, proved to be of great practical and theoretical interest 4, 5. Due to the polar nature of the hydrogen bonding end groups and the nonpolar nature of the polydimethylsiloxane chain, a transient network is formed wherein the polar end groups tend to associate with each other.…”

Section: Introductionmentioning

confidence: 99%

Novel materials based on silicone-acrylate copolymer networks

Mazurek¹,

Kinning²,

Kinoshita³

2001

J. Appl. Polym. Sci.

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This article presents a broad class of materials made by copolymerization of a family of telechelic free radically polymerizable siloxanes with various acrylate monomers that polymerize to form high Tg polymers. Films with properties ranging from strong elastomers to plastics have been obtained by UV‐initiated bulk copolymerization of functional siloxanes dissolved in acrylate monomers (in the presence of a photoinitiator). The molecular weight of the functional siloxanes, the nature of functional endgroups, the choice of (meth)acrylate comonomer, and the siloxane/acrylate ratio all have a rather dramatic effect on the morphology, and thus, on the properties of the copolymeric networks. Physical properties of the materials, such as optical appearance and mechanical and transport properties are correlated with the unique morphologies observed by TEM studies. Unusual properties such as reversible whitening of some of the materials and low Poisson ratios have been attributed to the microcavitation observed when high Tg acrylate domains interfere with the network deformation. Networks composed of high Tg acrylates (major fraction) coreacted with elastomeric siloxanes can provide heat‐shrinkable materials when they are elongated at temperatures higher than the Tg of the corresponding polyacrylates and quenched. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 159–180, 2001

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“…That would lead to the formation within the domains of more than one crosslinking-or chain-extension site, which could maintain an ability to hydrogen bond. It is believed that the liquid silicone rubbers described in this article can provide useful models in the studies of various aspects of rubber elasticity, as pointed out by the earlier work by Gent et al 15 From the same silicone diamine starting materials, telechelic siloxanes with different functional groups were derived. These liquid silicone rubbers are capable of low temperature curing via UV-initiated freeradical polymerization.…”

Section: Discussionmentioning

confidence: 93%

Telechelic siloxanes with hydrogen‐bonded polymerizable end groups. I. Liquid rubbers and elastomers

Leir

Galkiewicz

Kantner

et al. 2010

J of Applied Polymer Sci

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Functional siloxanes are widely used in the synthesis of model networks used in rubber elasticity studies, and various functional siloxanes are also used in the synthesis of silicone rubbers. We present here the results of studies of two classes of telechelic, free-radically polymerizable siloxanes carrying either amide or urea groups attached at both ends of siloxane chain. The presence of polar, hydrogen-bonding end-groups favors the formation of aggregates which is reflected in the drastically increased viscosity of the resulting ''liquid rubbers.'' In addition, such aggregation accounts for high local concentrations of reactive groups thus making it possible to have high molecular weight precursors undergo facile room temperature polymerization. In this article, we study the effect of the nature of these functional groups on the viscosity of polymerizable ''liquid rubbers,'' finding that the different endgroups lead to dramatically different viscosities. We also study the silicone rubber films obtained by a UV-initiated free-radical polymerization of the liquid rubbers, using dynamic mechanical analysis and large-strain uniaxial deformation. We find here that important properties such as plateau modulus and Young's modulus are highly dependent on both endgroup type and precursor molecular weight. The crosslinking of telechelic siloxanes in dilution was also studied to further explore the effect of crosslink density of the mechanical properties of the model networks. Finally, we evaluated the role of dangling ends within the networks through the incorporation of monofunctional macromers.

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Experimental study of molecular entanglement in polymer networks

Cited by 25 publications

References 17 publications

Transparent Organogel Films Showing Extremely Efficient and Durable Anti-Icing Performance

Transparent Organogel Films Showing Extremely Efficient and Durable Anti-Icing Performance

Novel materials based on silicone-acrylate copolymer networks

Telechelic siloxanes with hydrogen‐bonded polymerizable end groups. I. Liquid rubbers and elastomers

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