Real-Space Identification of Intermolecular Bonding with Atomic Force Microscopy

Zhang, Jun; Chen, Pengcheng; Yuan, Bo; Ji, Wei; Cheng, Zhihai; Qiu, Xiaohui

doi:10.1126/science.1242603

Cited by 400 publications

(361 citation statements)

References 27 publications

Supporting

Mentioning

340

Contrasting

Unclassified

Order By: Relevance

“…4(f)]. Note that in the case of atomically resolved AFM images of molecules using CO tips [8,[51][52][53][54], forces of shorter range are explored and the atomic contrast is dominated by Pauli repulsion [8,55]. In addition, there the interpretation is further complicated by the non-planarity of the sample and the tilting of the CO tip [52,56].…”

Section: Discussionmentioning

confidence: 99%

Investigating atomic contrast in atomic force microscopy and Kelvin probe force microscopy on ionic systems using functionalized tips

et al. 2014

View full text Add to dashboard Cite

Noncontact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM) have become important tools for nanotechnology; however, their contrast mechanisms on the atomic scale are not entirely understood. Here we used chlorine vacancies in NaCl bilayers on Cu(111) as a model system to investigate atomic contrast as a function of applied voltage, tip height, and tip functionalization. We demonstrate that the AFM contrast on the atomic scale decisively depends on both the tip termination and the sample voltage. On the contrary, the local contact potential difference (LCPD) acquired with KPFM showed the same qualitative contrast for all tip terminations investigated, which resembled the contrast of the electric field of the sample. We find that the AFM contrast stems mainly from electrostatic interactions but its tip dependence cannot be explained by the tip dipole alone. With the aid of a simple electrostatic model and by density functional theory we investigate the underlying contrast mechanisms.

show abstract

Section: Discussionmentioning

confidence: 99%

Investigating atomic contrast in atomic force microscopy and Kelvin probe force microscopy on ionic systems using functionalized tips

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Whereas different tip functionalizations have been reported [2,3], CO was used most often, and is now being widely applied [2][3][4][5][6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Image correction for atomic force microscopy images with functionalized tips

et al. 2014

View full text Add to dashboard Cite

It has been demonstrated that atomic force microscopy imaging with CO-functionalized tips provides unprecedented resolution, yet it is subject to strong image distortions. Here we propose a method to correct for these distortions. The lateral force acting on the tip apex is calculated from three-dimensional maps of the frequency shift signal. Assuming a linear relationship between lateral distortion and force, atomic force microscopy images could be deskewed for different substrate systems.

show abstract

“…In addition, previous studies of the intermolecular hydrogen bonds between phenolic hydroxyls 21 24 , concur that closely stacked catechols at surfaces provide strong intermolecular hydrogen bonds when brought into contact. The synchrotron near-edge X-ray absorption fine structure (NEXAFS; Fig.…”

mentioning

confidence: 97%

Surface-initiated self-healing of polymers in aqueous media

et al. 2014

View full text Add to dashboard Cite

Polymeric materials that intrinsically heal at damage sites under wet or moist conditions are urgently needed for biomedical and environmental applications [1][2][3][4][5][6] . Although hydrogels with self-mending properties have been engineered by means of mussel-inspired metal-chelating catechol-functionalized polymer networks 7-10 , biological self-healing in wet conditions, as occurs in self-assembled holdfast proteins in mussels and other marine organisms 11,12 , is generally thought to involve more than reversible metal chelates. Here we demonstrate self-mending in metal-free water of synthetic polyacrylate and polymethacrylate materials that are surface-functionalized with mussel-inspired catechols. Wet self-mending of scission in these polymers is initiated and accelerated by hydrogen bonding between interfacial catechol moieties, and consolidated by the recruitment of other non-covalent interactions contributed by subsurface moieties. The repaired and pristine samples show similar mechanical properties, suggesting that the triggering of complete self-healing is enabled underwater by the formation of extensive catechol-mediated interfacial hydrogen bonds.All polymeric materials suffer damage in the course of their functional lifetimes. Few, if any, completely heal at damage sites. Despite recent progress in the design of self-mending polymeric materials based on crack-activated crosslinking 1 , light 2 , heat 3 or other external stimuli 4 , these remain less than perfectly healed, and, in the case of polymers in wet environments, self-healing technologies are even more limited than those engineered for dry conditions. Mussel adhesive holdfasts exhibit significant self-healing capabilities 11,12 , although the molecular mechanisms involved are poorly understood. Notwithstanding this, the selfmending adhesion and cohesion of isolated dopa (3,4-dihydroxyphenyl-L-alanine)-containing adhesive proteins were shown to rely critically on maintaining dopa in an acidic and reducing environment 13,14 . Significantly different conditions are required to recapitulate the self-healing cohesion of tris-dopa-Fe 3+ -mediated complexes in proteins and polymers [7][8][9]15 . Such results increasingly suggest the importance of dopa, but also its subtle and diverse interfacial reactivity vis-à-vis the traditional and still widely held view that dopa, and catechols generally, function primarily as crosslinkers after their 2-electron oxidation to quinones 16 . To better assess the contribution of catechol to polymer selfhealing in a reducing (pH 3), metal-free wet environment, we prepared a material from common, water-insoluble synthetic acrylic polymers having a catechol-functionalized surface. These materials are completely self-healing in a process initiated by catecholmediated interfacial hydrogen bonding, and consolidated by followup interactions (for example, hydrophobic and steric) after a brief compression (∼6 × 10 4 Pa). The crucial and robust roles played by

show abstract

Real-Space Identification of Intermolecular Bonding with Atomic Force Microscopy

Cited by 400 publications

References 27 publications

Investigating atomic contrast in atomic force microscopy and Kelvin probe force microscopy on ionic systems using functionalized tips

Investigating atomic contrast in atomic force microscopy and Kelvin probe force microscopy on ionic systems using functionalized tips

Image correction for atomic force microscopy images with functionalized tips

Surface-initiated self-healing of polymers in aqueous media

Contact Info

Product

Resources

About