Adhesion between Solid Surfaces in Polymer Melts:  Bridging of Single Chains

Sun, Gexiao; Butt, Hans‐Jürgen

doi:10.1021/ma0497714

Cited by 36 publications

(40 citation statements)

References 33 publications

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“…These attractive interactions decrease the mobility of the PDMS chains and hence increase the film viscosity. The spontaneous spreading of a PDMS droplet on Si indicates that the interaction between these materials is highly favourable, with PDMS chains adsorbing strongly at the interface, as has previously been reported [12,[20][21]. In comparison, a PDMS droplet deposited on the CF x O y film exhibited a 40 o contact angle, suggesting that the interaction between PDMS chains and the CF x O y film is less favourable than the interaction between PDMS and SiO 2 .…”

Section: Interpretation Of Resultssupporting

confidence: 61%

“…In cases where extreme confinement of molecules is conferred, liquid films were made to behave as if they were solids [9][10]. Similarly, researchers such as Ducker [11] and Butt [12] have used atomic force microscopy to study the lubrication behaviour, slip properties, and interfacial molecular organisation of thin liquid polymer films. Butt and co-workers have also studied the propensity of molecules to form brush-like layers at the solid/liquid interface, due to the end groups present in the molecular chains [13].…”

Section: Introductionmentioning

confidence: 99%

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Controlling thin liquid film viscosity via modification of substrate surface chemistry

Bowen

Cheneler

Adams

2013

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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The viscosity of thin films of liquid poly(dimethylsiloxane) have been studied on silicon and fluoropolymer-coated silicon by means of a perturbation technique applied using colloid probe atomic force microscopy. The liquid film supported by a silicon substrate exhibited a greater viscosity than the bulk liquid, due to the strong interaction between the molecules near to the liquid/solid interface. In comparison, the liquid film supported by a fluoropolymer-coated substrate exhibited a similar viscosity to the bulk liquid, due to the weak interaction between the liquid and the fluoropolymer surface. This demonstrates the possibility to control the viscosity of thin liquid films via selection of the substrate chemical properties.Keywords poly(dimethylsiloxane), thin film, viscosity, fluoropolymer, atomic force microscopy 2 1. Introduction Thin film structure and dynamics are topics of significant research interest, with applications in fields as diverse as electronics, healthcare technologies and biomedical engineering. It is well-established that the properties of ultrathin films can vary as a function of the film thickness [1-4] with polymer chain segments at the film/substrate interface exhibiting decreased mobility compared with the bulk film, whereas segments at the free surface exhibit greater mobility than the bulk film. The effect of this anisotropy affects the properties of materials which include viscosity [1], glass transition temperatures [2-3], diffusion coefficients [4], and rheological properties [5]. For systems where there was a favourable interaction between the film and the surface chemical moieties of the supporting substrate, the properties of the film differed from those of the bulk. Granick and co-workers have employed techniques such as the surface forces apparatus and extensively studied the properties of polymer melts, showing that geometric confinement reduces polymer chain mobility regardless of the presence or absence of favourable intermolecular interactions [6][7][8]. In cases where extreme confinement of molecules is conferred, liquid films were made to behave as if they were solids [9][10]. Similarly, researchers such as Ducker [11] and Butt [12] have used atomic force microscopy to study the lubrication behaviour, slip properties, and interfacial molecular organisation of thin liquid polymer films. Butt and co-workers have also studied the propensity of molecules to form brush-like layers at the solid/liquid interface, due to the end groups present in the molecular chains [13].

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Section: Interpretation Of Resultssupporting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Controlling thin liquid film viscosity via modification of substrate surface chemistry

Bowen

Cheneler

Adams

2013

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…Bridging forces have also been observed on the single molecule level with the AFM (see Section 11). They have also been observed in polymer melts [845].…”

Section: Steric Forcesmentioning

confidence: 69%

“…Experiments about the stretching behavior of a molecule have been performed with polymers in different solvents [833,845,[1062][1063][1064][1065][1066][1067][1068][1069][1070][1071][1072][1073][1074][1075][1076][1077], DNA [1078][1079][1080], RNA [1081] and other macromolecules [1082][1083][1084][1085][1086].…”

Section: Molecule Stretchingmentioning

confidence: 99%

Force measurements with the atomic force microscope: Technique, interpretation and applications

Butt

Cappella

Kappl

2005

Surface Science Reports

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3,246

2,949

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“…TiO 2 nanoparticles with average diameter of 20 nm were distributed homogeneously on the silicon wafer were prepared as described in detail before [176]. …”

Section: Surface Preparationmentioning

confidence: 99%

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

et al. 2006

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To optimize the handling of fine powders in industrial applications, understanding the interaction forces between single powder particles is fundamental. The forces between colloidal particles dominate the behavior of a great variety of materials, including paints, paper, soil, and many industrial processes. With the invention of the atomic force microscope (AFM), the direct measurement of the interaction between single micron-sized particles became possible. The adhesional contact between a particle and a substrate is a parameter for analyzing pull-off force data generated by AFM. The aim of this study was to understand surface interactions between fine particles. I measured the adhesion forces between AFM tips or particles attached to AFM cantilevers and different solid samples. Smooth and homogeneous surfaces such as silicon wafer, mica, or highly oriented pyrolytic graphite (HOPG), and more rough and heterogeneous surfaces such as iron particles or patterns of TiO 2 nanoparticles on silicon wafer were used. First, I addressed to the wellknown issue that AFM adhesion experiment results show wide distributions of adhesion forces rather than a single value. My experimental results show that variations in adhesion forces comprise fast (i.e., from one force curves to the next) random fluctuations and slower fluctuations, which occur over tens or hundreds of consecutive measurements. Slow fluctuations are not likely to be the result of variations in external factors such as lateral position, temperature, humidity, and so forth because those were kept constant. Even if two solid bodies are brought into contact under precisely the same conditions (same place, load, direction, etc.) the result of such a measurement will often not be the same as for the previous contact. The measurement itself will induce structural changes in the contact region which can change the value for the next adhesion force measurement.In the second part I studied the influence of humidity on the adhesion of nanocontacts. Humidity was adjusted relatively fast to minimize tip wear during one experiment. For hydrophobic surfaces, no signification change of adhesion force with humidity was observed. Adhesion force-versus-humidity curves recorded with hydrophilic surfaces either showed a maximum or continuously increased. I demonstrate that the results can be interpreted with simple continuum theory of the meniscus force. The meniscus force is calculated based on a model that includes surface roughness and takes into account different AFM tip (or particle) shapes by a two-sphere-model.Experimental and theoretical results show that the precise contact geometry has a critical influence on the humidity dependence of the adhesion force.Changes of tip geometry on the sub-10-nm length scale can completely change adhesion force-versus-humidity curves. Our model can also explain the differences between earlier AFM studies, where different dependencies of the adhesion force on humidity were observed.Keywords: Atomic force microscopy (AFM), cantile...

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Adhesion between Solid Surfaces in Polymer Melts: Bridging of Single Chains

Cited by 36 publications

References 33 publications

Controlling thin liquid film viscosity via modification of substrate surface chemistry

Controlling thin liquid film viscosity via modification of substrate surface chemistry

Force measurements with the atomic force microscope: Technique, interpretation and applications

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

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