Influence of the length and grafting density of PNIPAM chains on the colloidal and optical properties of quantum dot/PNIPAM assemblies

Tagit, Oya; Tomczak, Nikodem; Jafarpour, Aliakbar; Jańczewski, Dominik; Han, Ming‐Yong; Vancso, G. Julius; Herek, Jennifer Lynn

doi:10.1088/0957-4484/22/26/265701

Cited by 10 publications

(8 citation statements)

References 45 publications

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“…Anionic and cationic PNIPAM particles were prepared using batch radical polymerization. The cationic microgel was obtained following the protocol of Lo ´pez-Leo ´n et al 20 while for the anionic one we followed the protocol of Tagit et al 22 Polymerizations were performed in batches of 500 ml for the cationic microgel and 350 ml for the anionic one, in a 1000 ml volume capacity reactor. The amounts of each reactant used are shown in Table 1.…”

Section: Synthesis Of Pnipam Microgelsmentioning

confidence: 99%

Anions make the difference: insights from the interaction of big cations and anions with poly(N-isopropylacrylamide) chains and microgels

et al. 2015

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Minute concentrations of big hydrophobic ions have the ability to induce substantial effects in soft matter systems, including novel phases in lipid layers, giant charge inversion in colloids and nanostructuration in polymer surfaces in contact with water. The effects are so strong that the term "soft matter disruptors" was coined to describe their deep impact on interfaces, which goes far beyond that found by using the classical ions considered in lyotropic (Hofmeister) sequences. In these effects, solvation thermodynamics plays a fundamental role. Interestingly, it is possible to obtain big hydrophobic cations and anions with an almost identical size and structure (e.g. Ph4B(-), Ph4As(+)), which only differ in their central atom. Here we employ different techniques (Molecular Dynamics (MD) simulations, electrophoretic mobility and Atomic Force Microscopy (AFM)) to demonstrate the dramatic differences in the interaction of Ph4B(-) and Ph4As(+) with poly(N-isopropylacrylamide) (PNIPAM), a thermoresponsive polymer with expanded (well hydrated) and collapsed (poorly hydrated) states. Although both ions interact strongly with neutral PNIPAM chains and cationic or anionic PNIPAM microgels in the collapsed states, the effects of Ph4B(-) on PNIPAM are always substantially stronger than the effects of Ph4As(+). MD simulations predict that ion-PNIPAM free energy of interaction is four times larger for Ph4B(-) than for Ph4As(+). Electrokinetic and AFM experiments show that, acting as counter-ions, both ions are able to invert the charge of anionic or cationic PNIPAM microgels at minute concentrations, but the charge inversion due to Ph4B(-) is much larger than that obtained with Ph4As(+). Therefore, even for big ions of identical size, shape and valence, the affinity of anions and cations for interfaces is intrinsically different.

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Section: Synthesis Of Pnipam Microgelsmentioning

confidence: 99%

Anions make the difference: insights from the interaction of big cations and anions with poly(N-isopropylacrylamide) chains and microgels

et al. 2015

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“…Resulting composite material exhibits the swelling properties of the polymer matrix and the optical, magnetic or catalytic properties of the inorganic particle. In the last decade, such composite structures have been investigated and hybrid systems hosting, for instance, magnetic iron oxide [49], gold [50,51], silica nanoparticles [52] and quantum dots [53] have already been reported in the literature [54]. By this mean, 2D-organized arrays were synthesized, for instance with hybrid particles containing up to 20% wt% of ZnS, in which interparticles distance can be controlled [55], or 3D nanocrystal with gold hybrids with tunable spacings between gold cores ranging from 50 to 500 nm.…”

Section: Introductionmentioning

confidence: 99%

Encapsulated nanodiamonds in smart microgels toward self-assembled diamond nanoarrays

Girard

Benayoun

Blin

et al. 2013

Diamond and Related Materials

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We report on the successful attempt to synthesize thermoresponsive nanodiamonds hybrid microgels through a straightforward method. Resulting microgels exhibit smart properties, as the reversible collapsing of the structures when raising the temperature, with embedded nanodiamonds. Thanks to the colloidal and smart properties of the microgels, nanoscaled 2D self-assembled arrays of nanodiamonds with varying inter-particle distances were realized, without any lithographic processes, as an illustration of the promising properties of these novel diamond-based microgels. Such assemblies can constitute a first step toward a bottomup elaboration of innovative diamond-based devices.

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“…The study of Quantum dot (QD)-PNIPAm hybrid particles by FCS has also been recently reported [130]. This straightforward study described how FCS can be used to monitor changes in hydrodynamic radii near the LCST for particles having different length PNIPAm chains attached.…”

Section: Phase Transitions At the Lcstmentioning

confidence: 99%

Fluorescence Analysis of Thermoresponsive Polymers

Morris

Ryder

2015

Reviews in Fluorescence

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The use of microscale thin polymer films is widespread in biomedical science and engineering, with applications in areas such as tissue engineering, drug delivery, microfluidic devices, bio-adhesion mediators, and bio-actuators. Much attention is devoted to the use of functional polymers that display stimuliresponsive behavior with the intention of providing "smart" coatings. One potential example is the use of thin thermoresponsive polymer films as drug eluting coatings on medical devices, where not only does the polymer function as a drug reservoir but it also acts as a biocompatibility modulator to improve device performance.Often these thin polymer coatings have to be applied to complex geometries, which can cause problems for in-situ analysis. Another important consideration is the fact that these films have large surface area to mass ratios and thus water uptake can be significant. This is serious because coating stability, device efficacy, and long-term storage are influenced by the physiochemical properties of the polymer which are modulated by water content. Thus, there is a need for a rapid, non-contact, non-destructive, analytical method capable of analyzing thermoresponsive polymers in solution, and in-situ of the solid-state on medical devices. Fluorescence spectroscopy based methods can deal with both sample types and provide additional benefits in terms of high sensitivity and low probe concentrations, which provide for minimal sample disruption. This article gives a brief overview of the application of various fluorescence methods for the physicochemical characterization of thermoresponsive polymers such as poly (N-isopropylacrylamide), PNIPAm.

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Influence of the length and grafting density of PNIPAM chains on the colloidal and optical properties of quantum dot/PNIPAM assemblies

Cited by 10 publications

References 45 publications

Anions make the difference: insights from the interaction of big cations and anions with poly(N-isopropylacrylamide) chains and microgels

Anions make the difference: insights from the interaction of big cations and anions with poly(N-isopropylacrylamide) chains and microgels

Encapsulated nanodiamonds in smart microgels toward self-assembled diamond nanoarrays

Fluorescence Analysis of Thermoresponsive Polymers

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