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Memory effects in annealed hybrid gold nanoparticles/block copolymer bilayers.

Torrisi V, Ruffino F, Licciardello A, Grimaldi MG, Marletta G - Nanoscale Res Lett (2011)

Bottom Line: The effect of the polymer chain mobility onto the organization of gold nanoparticle layer was assessed by heating the obtained hybrid PnBuA-b-PAA/Au NPs bilayer at T >Tg.The nanoparticles' distribution onto the different copolymer domains was found strongly affected by the annealing treatment, showing a peculiar memory effect, which modifies the AFM phase response of the Au NPs layer onto the polar domains, without affecting their surfacial composition.The effect is discussed in terms of the peculiar morphological features induced by enhanced mobility of polymer chains on the Au NPs layer.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN), Department of Chemical Sciences, University of Catania and CSGI, Viale A, Doria 6, 95125, Catania, Italy. vanna.torrisi@gmail.com.

ABSTRACT
We report on the use of the self-organization process of sputtered gold nanoparticles on a self-assembled block copolymer film deposited by horizontal precipitation Langmuir-Blodgett (HP-LB) method. The morphology and the phase-separation of a film of poly-n-butylacrylate-block-polyacrylic acid (PnBuA-b-PAA) were studied at the nanometric scale by using atomic force microscopy (AFM) and Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS). The templating capability of the PnBuA-b-PAA phase-separated film was studied by sputtering gold nanoparticles (NPs), forming a film of nanometric thickness. The effect of the polymer chain mobility onto the organization of gold nanoparticle layer was assessed by heating the obtained hybrid PnBuA-b-PAA/Au NPs bilayer at T >Tg. The nanoparticles' distribution onto the different copolymer domains was found strongly affected by the annealing treatment, showing a peculiar memory effect, which modifies the AFM phase response of the Au NPs layer onto the polar domains, without affecting their surfacial composition. The effect is discussed in terms of the peculiar morphological features induced by enhanced mobility of polymer chains on the Au NPs layer.

No MeSH data available.


Height distribution of the micelles after each deposition step of as deposited and annealed samples: Micelles height versus annealing time (d) and relative height distribution of micelles size of PnBuA-b-PAA film before sputtering (a), after sputtering (b), after thermal annealing (c).
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Figure 3: Height distribution of the micelles after each deposition step of as deposited and annealed samples: Micelles height versus annealing time (d) and relative height distribution of micelles size of PnBuA-b-PAA film before sputtering (a), after sputtering (b), after thermal annealing (c).

Mentions: In order to exclude the first hypothesis, we consider the height of circular domains (obtained by section analysis) versus annealing time. Such a graphic (Figure 3) shows that the height of circular domains remains constant (〈z〉 = 1.69 nm) after annealing treatment. From the AFM images the circular domains' height distributions were determined by using a software (Nanoscope IIIa) that defines each circular domains area by the surface image sectioning of a plane that was positioned at half micelle height. Each height distribution of circular domains was calculated on a statistical population of 50 circular domains. Each distribution was then fitted by a Gaussian function (the continuous line in each figure) which peak position was taken as the mean value and which FWHM (full width at half maximum) as the deviation on such mean value. The graphic of Figure 3 shows us that annealing process does not change circular domains' height and this fact allows us to exclude the first hypothesis: the preferential diffusion of gold driven by block copolymer template. On the other hand, the thermodynamic basis of hypotheses 1 and 2 is the surface-free energy minimization of the hybrid gold/polymer system. In fact, generally, cluster growth is regulated by the vapour pressure at the surfaces of the cluster, P(R), depending on the curvature of the surface and it is driven by the minimization of the total surface free energy. For spherical clusters with a radius R, the vapour pressure at the surface of the cluster is given by the following relation according to the Gibbs-Thompson equation [38]


Memory effects in annealed hybrid gold nanoparticles/block copolymer bilayers.

Torrisi V, Ruffino F, Licciardello A, Grimaldi MG, Marletta G - Nanoscale Res Lett (2011)

Height distribution of the micelles after each deposition step of as deposited and annealed samples: Micelles height versus annealing time (d) and relative height distribution of micelles size of PnBuA-b-PAA film before sputtering (a), after sputtering (b), after thermal annealing (c).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211219&req=5

Figure 3: Height distribution of the micelles after each deposition step of as deposited and annealed samples: Micelles height versus annealing time (d) and relative height distribution of micelles size of PnBuA-b-PAA film before sputtering (a), after sputtering (b), after thermal annealing (c).
Mentions: In order to exclude the first hypothesis, we consider the height of circular domains (obtained by section analysis) versus annealing time. Such a graphic (Figure 3) shows that the height of circular domains remains constant (〈z〉 = 1.69 nm) after annealing treatment. From the AFM images the circular domains' height distributions were determined by using a software (Nanoscope IIIa) that defines each circular domains area by the surface image sectioning of a plane that was positioned at half micelle height. Each height distribution of circular domains was calculated on a statistical population of 50 circular domains. Each distribution was then fitted by a Gaussian function (the continuous line in each figure) which peak position was taken as the mean value and which FWHM (full width at half maximum) as the deviation on such mean value. The graphic of Figure 3 shows us that annealing process does not change circular domains' height and this fact allows us to exclude the first hypothesis: the preferential diffusion of gold driven by block copolymer template. On the other hand, the thermodynamic basis of hypotheses 1 and 2 is the surface-free energy minimization of the hybrid gold/polymer system. In fact, generally, cluster growth is regulated by the vapour pressure at the surfaces of the cluster, P(R), depending on the curvature of the surface and it is driven by the minimization of the total surface free energy. For spherical clusters with a radius R, the vapour pressure at the surface of the cluster is given by the following relation according to the Gibbs-Thompson equation [38]

Bottom Line: The effect of the polymer chain mobility onto the organization of gold nanoparticle layer was assessed by heating the obtained hybrid PnBuA-b-PAA/Au NPs bilayer at T >Tg.The nanoparticles' distribution onto the different copolymer domains was found strongly affected by the annealing treatment, showing a peculiar memory effect, which modifies the AFM phase response of the Au NPs layer onto the polar domains, without affecting their surfacial composition.The effect is discussed in terms of the peculiar morphological features induced by enhanced mobility of polymer chains on the Au NPs layer.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN), Department of Chemical Sciences, University of Catania and CSGI, Viale A, Doria 6, 95125, Catania, Italy. vanna.torrisi@gmail.com.

ABSTRACT
We report on the use of the self-organization process of sputtered gold nanoparticles on a self-assembled block copolymer film deposited by horizontal precipitation Langmuir-Blodgett (HP-LB) method. The morphology and the phase-separation of a film of poly-n-butylacrylate-block-polyacrylic acid (PnBuA-b-PAA) were studied at the nanometric scale by using atomic force microscopy (AFM) and Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS). The templating capability of the PnBuA-b-PAA phase-separated film was studied by sputtering gold nanoparticles (NPs), forming a film of nanometric thickness. The effect of the polymer chain mobility onto the organization of gold nanoparticle layer was assessed by heating the obtained hybrid PnBuA-b-PAA/Au NPs bilayer at T >Tg. The nanoparticles' distribution onto the different copolymer domains was found strongly affected by the annealing treatment, showing a peculiar memory effect, which modifies the AFM phase response of the Au NPs layer onto the polar domains, without affecting their surfacial composition. The effect is discussed in terms of the peculiar morphological features induced by enhanced mobility of polymer chains on the Au NPs layer.

No MeSH data available.