Glass transition of poly(methyl methacrylate) nanospheres in aqueous dispersion

Feng, Shuo; Chen, Yuenan; Mai, BiYun; Wei, WanChu; Zheng, Caixia; Wu, Qing; Liang, Guodong; Gao, Haiyang; Zhu, Fangming

doi:10.1039/c4cp01849d

Cited by 17 publications

(10 citation statements)

References 54 publications

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“…76 The solid and dotted lines represent a best fit to the data for the template-supported PMMA tubes (t tube ≈ 2 R g + 9 nm) and the supported PDMS thin films (thickness ≈ 2 R g + 3 nm). T g,bulk = 9 K. The increase in T g with confinement is due to the attractive hydrogen-bonding interactions between the PMMA ester groups and the hydroxyl groups 8,27,40 on the template surface. These attractive interactions between the polymer and template surface result in decreased segmental mobility near the interface which can propagate into the nanotube interior.…”

Section: Design and Fabrication Of Supported Pmma Nanotubesmentioning

confidence: 99%

“…Understanding the behavior of polymers in other geometries gives insight into the factors which affect T g and opens up the opportunity to better control or tune properties. Recent DSC studies on the T g -confinement behavior of aqueous dispersions of polymer nanospheres and quasi-nanospheres by Priestley and coworkers [37][38][39] and Feng et al 40,41 have reported that T g decreases with decreasing sphere size.…”

Section: Introductionmentioning

confidence: 99%

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Poly(methyl methacrylate) nanotubes in AAO templates: Designing nanotube thickness and characterizing the T-confinement effect by DSC

Tan

Torkelson

2016

Polymer

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We used differential scanning calorimetry (DSC) to study the effect of confinement on the glass transition temperature (T g) of poly(methyl methacrylate) (PMMA) nanotubes supported in anodic aluminum oxide (AAO) templates. We created nanotubes by wetting templates with polymer melts and developed a design equation relating tube thickness (t tube) with bulk radius of gyration (R g): (t tube ≈ 2 R g + 9 nm). The results indicate that t tube depends on overall conformation and size of the polymer coils and can be tuned at the nanoscale by polymer molecular weight. The T g of AAO template-supported PMMA nanotubes increases with decreasing t tube , with T g,tube-T g,bulk = 12 K in 18-nm-thick nanotubes; we attribute the T g increase to hydrogen bonds between PMMA ester side groups and hydroxyl groups on the surface of the γ-Al 2 O 3 templates. Using ellipsometry, we characterized T g-confinement effects for PMMA films supported on Si/SiO x , sputtered Al 2 O 3 and sapphire (α-Al 2 O 3). Films supported on substrates with higher concentrations of surface hydroxyl groups (α-Al 2 O 3 > sputtered-Al 2 O 3 > Si/SiO x) exhibit larger T g-confinement effects. The DSC-determined T g enhancements for nanotubes supported in γ-Al 2 O 3 templates fall between the ellipsometry-determined T g enhancements determined for PMMA films on α-Al 2 O 3 and those for films on sputtered-Al 2 O 3. These results show that molecular weight provides for tunability of polymer nanotube thickness in AAO templates, that there is excellent agreement in confinement effects measured by DSC and by ellipsometry, and that T g can be tuned by modulating the levels of interfacial, polymer-substrate interactions by using surfaces with different chemical or crystallographic properties.

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Section: Design and Fabrication Of Supported Pmma Nanotubesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Poly(methyl methacrylate) nanotubes in AAO templates: Designing nanotube thickness and characterizing the T-confinement effect by DSC

Tan

Torkelson

2016

Polymer

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“…Finally, it is worth recalling that a number of polymer nanocomposites exhibit no experimentally detectable deviations from bulk T g . More recently, a number of works showed negative T g deviations in PS [38,51,193,194] and PMMA [50] nanospheres. This was the case for low silica contents in the polymer.…”

Section: Thermal Glass Transitionmentioning

confidence: 99%

“…This was the case for low silica contents in the polymer. In the works of Feng et al [50,51], it was demonstrated how the presence of a surfactant on the surface of the nanosphere and its nature (ionic or nonionic) has a crucial effect on the magnitude (if any) of deviations from bulk T g . Nanocomposites exhibiting no evidence of deviation from bulk T g are those of PVAc with neat silica [3] and poly(ether imide) (PEI) with carbon fiber [35].…”

Section: Thermal Glass Transitionmentioning

confidence: 99%

“…Nanocomposites exhibiting no evidence of deviation from bulk T g are those of PVAc with neat silica [3] and poly(ether imide) (PEI) with carbon fiber [35]. The opposite was shown for nanospheres made of a polar polymer, PMMA [50]. Similarly to polymer nanocomposites the radius of curvature of the spheres may play a role in determining the magnitude of T g deviations.…”

Section: Thermal Glass Transitionmentioning

confidence: 99%

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Effect of Confinement Geometry on Out-of-Equilibrium Glassy Dynamics

Cangialosi

2015

Non-Equilibrium Phenomena in Confined Soft Matter

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Glassy dynamics under nanoscale confinement have been subject of under intense debate in soft matter physics in the last 20 years. Scientific impetus in the field was provided by the increasing employment of glasses confined at the nanoscale. Furthermore, investigation of confined glasses may deliver information of the still unsolved problem of the glass transition. Within this context, the present chapter critically discusses the experimental findings in the field. Special attention is devoted to literature dealing with polymers under 1-D confinement, that is, thin polymer film. Results on different confinement geometries, such as polymer nanocomposites and nanospheres, are discussed as well. In discussing these results, we emphasize how the out-of-equilibrium dynamics, that is, the glass transition temperature (T g ) and the spontaneous evolution towards equilibrium in the so-called physical aging regime, is in numerous cases decoupled from the equilibrium dynamics, namely the rate of spontaneous fluctuations in the glass former. In particular, arguments based exclusively on the modification of the rate of spontaneous fluctuations in confinement are not able to provide a comprehensive description of the deviation of the T g and the rate of physical aging. In the search for the factors affecting the out-of-equilibrium dynamics in confinement, we show solid experimental evidence that this is mainly determined by the amount of free interface. In this sense the crucial role of irreversible chain adsorption is highlighted. Finally a framework, based on free volume holes diffusion (FVHD), to describe the entire phenomenology of glassy dynamics in confinement is reviewed. This is able to catch the enhancement of the out-of-equilibrium dynamics, that is, the T g depression and the speed-up of physical aging in confinement, with no need to invoke any acceleration of the rate of spontaneous fluctuations of the polymer.

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A Self‐Assembling Octahedral Aggregate of Poly(methyl methacrylate) Nanospheres on a Silver Substrate

Chen

Zhang

et al. 2015

ChemPlusChem

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Al arge-area, self-assembling, octahedral aggregatec omposed of poly(methylm ethacrylate) nanospheres( PMMA-NS)w as constructed by using ao ne-step electrodeposition approach from an aqueous solution containing AgNO 3 and PMMA-NS as sacrificiale lectrolytes. The surfacec hain geometry of the product was revealed by Ramans pectroscopy. The results revealed that the orientationo fc hains of the PMMA-NSo ctahedron is differentf rom that of the nonaggregatedP MMA-NS because of the interfacial interactions between the polymer chain and Ag metal. This can be explained by the crystal surface free energy of the octahedral Ag substrate, which gives rise to diverse conformations of the PMMA molecular chain at different surfacer egions of the silver substrate. In addition, the adsorptive properties of PMMA-NS octahedra are such that the adsorbent-adsorbate system is cost-effective,e fficient and fast for the removal of dyes from contaminated wastewater.

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Glass transition of poly(methyl methacrylate) nanospheres in aqueous dispersion

Cited by 17 publications

References 54 publications

Poly(methyl methacrylate) nanotubes in AAO templates: Designing nanotube thickness and characterizing the T-confinement effect by DSC

Poly(methyl methacrylate) nanotubes in AAO templates: Designing nanotube thickness and characterizing the T-confinement effect by DSC

Effect of Confinement Geometry on Out-of-Equilibrium Glassy Dynamics

A Self‐Assembling Octahedral Aggregate of Poly(methyl methacrylate) Nanospheres on a Silver Substrate

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