Polymer surface structure

Surface properties are important to the physical and chemical behavior of polymers. Similar to smaller molecules, polymer surface structures can be determined using a variety of techniques including AES, near-field optical microscopy, electron microscopy, SPM, SIMS, and certain IR and MS procedures. 

Biological and physiological criteria are related to the specific applications of biomaterials in the body. Fundamentals of blood compatibility are analyzed expertly in the overview by Hoffman (16) included in this volume. Blood-compatible biomaterials should not cause cancer or teratological effects, and they should not be toxic. Toxicity may be related to functional groups of the polymer surface structure, or to migration of residual monomers under quiescent or flow conditions. 

Despite the diflBculties of interpretation of these measurements and of identification of the various anomalies, the diflFusion coeflBcient is a valuable parameter which provides structural information at a level that no other technique can provide. Furthermore, because diflFusion proceeds inwards from a polymer surface, the surface is the prime structural unit studied by this technique. DiflFusion analysis is expected to be an important tool for investigating the eflFect of processing on polymer surface structure. 

Chen, J., Zhuang, H., Zhao, J., Gardella Jr., J.A. Solvent effects on polymer surface structure. Surf Interface Anal. 31, 713-720 (2001)... 

IPN An Easy Waterborne Process for Polymer Surface Structuration... 

For selected materials with MDI or DBDI obtained by us, we examined the polymer surface structure by means of SEM, under three conditions (a) initially after synthesis, on original PUs sheets (b) while stretching the polymers to a 300% strain amplitude (c) on materials recovered after rupture. SEM was performed on the... 

CONTROL OF POLYMER SURFACE STRUCTURE BY TAILORED GRAFT COPOLYMERS... 

Hexemer, A., Sivaniah, E., Kramer, E.J. et al. (2004) Managing polymer surface structure using surface active block copolymer mixtures. Journal of Polymer Science Part B-Polymer Physics, 42,411 20. 

Another area where it appears that rapid progress will be possible in the future is the friction and wear of polymer surfaces. This area is important in a number of practical applications ranging from the behavior of thin layers of polymers as lubricants for magnetic disk heads to the lifetime of polymer protective coatings for ship hulls affected by wear due to waterborne debris. In the related area of drag reduction, a currently dormant field, precise control of polymer surface structure or the use of slowly released soluble polymers, which might affect hydrodynamics, may offer new approaches. 

The lubricating properties of tears are an important feature in normal blinking. Kalachandra and Shah measured the coefficient of friction of ophthalmic solutions (artificial tears) on polymer surfaces and found no correlation with viscosity, surface tension or contact angle [58]. The coefficient of friction appears to depend on the structure of the polymer surfaces and decreases with increasing load and sliding speed. 

Other topics recently studied by XPS include the effects of thermal treatment on the morphology and adhesion of the interface between Au and the polymer trimethylcy-clohexane-polycarbonate [2.72] the composition of the surfaces and interfaces of plasma-modified Cu-PTFE and Au-PTFE, and the surface structure and the improvement of adhesion [2.73] the influence of excimer laser irradiation of the polymer on the adhesion of metallic overlayers [2.74] and the behavior of the Co-rich binder phase of WC-Co hard metal and diamond deposition on it [2.75]. 

In the many reports on photoelectron spectroscopy, studies on the interface formation between PPVs and metals, focus mainly on the two most commonly used top electrode metals in polymer light emitting device structures, namely aluminum [55-62] and calcium [62-67]. Other metals studied include chromium [55, 68], gold [69], nickel [69], sodium [70, 71], and rubidium [72], For the cases of nickel, gold, and chromium deposited on top of the polymer surfaces, interactions with the polymers are reported [55, 68]. In the case of the interface between PPV on top of metallic chromium, however, no interaction with the polymer was detected [55]. The results concerning the interaction between chromium and PPV indicates two different effects, namely the polymer-on-metal versus the metal-on-polymer interface formation. Next, the PPV interface formation with aluminum and calcium will be discussed in more detail. 

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