Growth of Polymer Nanorods with Different Core–Shell Dynamics via Capillary Force in Nanopores

Sha, Ye; Li, Linling; Wang, Xiaoliang; Wan, Yuanxin; Yu, Jie; Xue, Gi; Zhou, Dongshan

doi:10.1021/ma5017715

Cited by 24 publications

(33 citation statements)

References 61 publications

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“…While this perturbation length scale is smaller than the 12 nm threshold observed by Itagaki et al, Barbaro and Steiner suggest that lower entanglement density could be responsible for reductions in viscosity measured in films as thick as 100 nm . Contrary to this, the quenching ratio of dyes attached to separate PS or PnBMA chains confined to AAO nanopores have been shown to increase with decreasing pore size indicating greater entanglement density under cylindrical hard confinement …”

Section: Fluorescence Measurements Of Diffusion and Mobilitymentioning

confidence: 76%

“…[201] Contrary to this, the quenching ratio of dyes attached to separate PS or PnBMA chains confined to AAO nanopores have been shown to increase with decreasing pore size indicating greater entanglement density under cylindrical hard confinement. [202,203] Fluorescence techniques have been utilized to study the complex dynamics of polymer systems over a variety of length and timescales. Rotational mobility and reorientation of dyes provided insight into the dynamic heterogeneities that broaden upon confinement, also illustrating the presence of a high mobility surface layer.…”

Section: Fluorescence Measurements Of Diffusion and Mobilitymentioning

confidence: 99%

See 1 more Smart Citation

21st Century Advances in Fluorescence Techniques to Characterize Glass‐Forming Polymers at the Nanoscale

Burroughs

Christie

Gray

et al. 2017

Macro Chemistry & Physics

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properties. [9,10] While fluorescence has been used extensively to characterize bulk properties of polymers, including glass transition temperature (T g ) [11][12][13] and polymerization conversion, [13] it is particularly well-suited to study polymers at the nanoscale. This is largely due to the fact that fluorescence techniques enable sensitive and location-specific measurements with high resolution.In this review, we focus on the use of both steady-state and transient fluorescence techniques to characterize physical properties of polymers over nanoscale dimensions. This length scale can refer to film thickness in single-component polymer films, interparticle spacing in nanocomposites, domain spacing in phaseseparated block copolymers, and distance from the polymer-polymer interface in multicomponent immiscible blends. Several geometries characterized via fluorescence are shown in Figure 1. Prior to delving into specific contributions, the basic principles and techniques of fluorescence are presented as well as a brief introduction to the behavior of confined polymers. We then present recent advances in fluorescence techniques for polymer physical characterization under confinement with regards to the glass transition temperature, physical aging, mobility and diffusion, and mechanical response. Through this examination of the literature, we illustrate the unique ability of fluorescence to characterize polymers in confined and complex geometries, providing insights into the influences of interfaces and nanostructure on material properties through sensitive, location-specific measurements. We conclude with a view toward future areas of research in which fluorescence has the potential to be impactful. Introduction to FluorescenceWhen a molecule absorbs energy via light, an electron is excited to a higher energy state, returning to the ground state through either radiative or nonradiative deactivation. This electronic excitation and return to the ground state is a combination of three photophysical processes: absorption, luminescence, and nonradiative decay. [33] Fluorescence is a luminescent process in which the excited-state electron returns to the ground state by emitting a photon, i.e., light. As shown in a simplified Jablonski Polymer CharacterizationCharacterization of polymers at the nanometer-length scale has become increasingly important with the growth and expansion of nanotechnology. Due to limitations of sensitivity and specificity that persist with traditional materials characterization techniques, there is a growing need to develop new tools to measure the properties of confined polymer systems. Within the past 20 years, fluorescence characterization techniques have emerged to address this challenge. This review focuses on the employment of fluorescence techniques such as temperature-and time-dependent steady-state intensity, fluorescence recovery after photobleaching, and nonradiative energy transfer to study polymer behavior at the nanoscale. Properties discussed include glass transition temperatur...

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Section: Fluorescence Measurements Of Diffusion and Mobilitymentioning

confidence: 76%

Section: Fluorescence Measurements Of Diffusion and Mobilitymentioning

confidence: 99%

21st Century Advances in Fluorescence Techniques to Characterize Glass‐Forming Polymers at the Nanoscale

Burroughs

Christie

Gray

et al. 2017

Macro Chemistry & Physics

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“…FRET has been proven as a spectroscopic ruler for characterizing the distance between fluorescent donor and acceptor [29]. Usually, by controlling the labeling strategies of such chromophores, different kinds of physical properties sensitive to distance can be explored [3,34,35,36,37,38,39]. For linear polymer chains, there exists two types of intrachain labeling strategies: random labeling, where the two chromophores are attached randomly onto one single chain together, and chain-end labeling, where the fluorescent acceptor and donor are fixed at the ends of polymer chains with the aid of site-specific ATRP and click chemistry (seen in Figure 1b) [31,40,41].…”

Section: Resultsmentioning

confidence: 99%

Conformational Transitions of Polymer Chains in Solutions Characterized by Fluorescence Resonance Energy Transfer

Qin

Sha

et al. 2018

Polymers

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The critical overlap concentration C* is an important concept in polymer solutions and is defined as the boundary between dilute and semidilute regimes. In this study, the chain conformational changes of polystyrene (PS) with both high (Mn = 200,000 Da) and low (Mn = 13,000 Da) molecular weights in cis-decalin were compared by intrachain fluorescence resonance energy transfer (FRET). The random labeling of donor and acceptor chromophores strategy was employed for long PS chains, whereas chain-end labeling was used for short PS chains. By monitoring the spectroscopic intensity ratio between acceptor and donor, the concentration dependence on chain conformation from dilute to semidilute solutions was determined. Both long and short chains exhibit a conformational transition concentration, above which the polymer chains begin to collapse with concentration significantly. Interestingly, for randomly labeled polymer long chains, such concentration is consistent with C* determined from the viscosity result, below which only slight conformational change of polymer chain takes place. However, for the chain-end labeled short chain, the conformational transition concentration takes place earlier than C*, below which no significant polymer conformation change is observed.

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“…Previous FRET studies usually investigated the interchain distances by labeling fluorescent donor and acceptor chromophores on separate polymer chains . The intrachain conformational changes could also be characterized by intrachain FRET .…”

Section: Introductionmentioning

confidence: 99%

Associated inter‐ and intrachain conformational transitions in polystyrene solutions

Chen

Sha

Gao

et al. 2017

J Polym Sci B Polym Phys

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Understanding the conformational changes of polymeric chains in solutions is an essential and integral part of polymer physics. By increasing the concentration of polymer solutions from dilute to semidilute regime, the critical chain overlapping has been reported at the concentration termed as C*. In this study, the associated inter‐ and intrachain conformational transitions in polystyrene (PS) solutions are reported. By comparing the spectroscopic intensity ratio versus concentration for an intrachain PS system, a break point was observed in good solvent which coincided with the theoretically predicted C*. Moreover, the intrachain conformation showed no obvious change below C*, while significant collapse started to occur above C*. This result reveals a new insight in polymer physics, since traditionally the size of polymer chains is considered to decrease weakly regarding the concentration change in the semidilute regime. It is important to find such an abrupt intrachain conformational transition between the dilute and semidilute solutions and provide the first experimental observation that inter‐ and intrachain conformational transitions are correlated to one the other. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1373–1379

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Growth of Polymer Nanorods with Different Core–Shell Dynamics via Capillary Force in Nanopores

Cited by 24 publications

References 61 publications

21st Century Advances in Fluorescence Techniques to Characterize Glass‐Forming Polymers at the Nanoscale

21st Century Advances in Fluorescence Techniques to Characterize Glass‐Forming Polymers at the Nanoscale

Conformational Transitions of Polymer Chains in Solutions Characterized by Fluorescence Resonance Energy Transfer

Associated inter‐ and intrachain conformational transitions in polystyrene solutions

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