In this paper, the application of instrumented indentation devices to the measurement of the elastic modulus of polymeric materials is reviewed. This review includes a summary of traditional analyses of load‐penetration data and a discussion of associated uncertainties. Also, the use of scanning probe microscopes to measure the nanoscale mechanical response of polymers is discussed, particularly with regard to the associated limitations. The application of these methods to polymers often leads to measurements of elastic modulus that are somewhat high relative to bulk measurements with potentially artificial trends in modulus as a function of penetration depth. Also, power law fits to indentation unloading curves are often a poor representation of the actual data, and the power law exponents tend to fall outside the theoretical range. These problems are likely caused by viscoelasticity, the effects of which have only been studied recently. Advancement of nanoindentation testing toward quantitative characterization of polymer properties will require material‐independent calibration procedures, polymer reference materials, advances in instrumentation, and new testing and analysis procedures that account for viscoelastic and viscoplastic polymer behavior.

A facile approach to unique 3D, patterned polymer brushes is based on visible‐light‐mediated controlled radical polymerization. The temporal and spatial control of the polymerization allows the patterning of polymer brushes from a uniform initiating layer using a simple photomask (see picture). Furthermore, gradient polymer brushes, patterned block copolymers, and complex 3D structures can be obtained by modulating light intensity.

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The fabrication of well-defined, multifunctional polymer brushes under ambient conditions is described. This facile method uses light-mediated, metal-free atom-transfer radical polymerization (ATRP) to grow polymer brushes with only microliter volumes required. Key to the success of this strategy is the dual action of N-phenylphenothiazine (PTH) as both an oxygen scavenger and polymerization catalyst. Use of simple glass cover slips results in a high degree of spatial and temporal control and allows for multiple polymer brushes to be grown simultaneously. The preparation of arbitrary 3D patterns and functional/emissive polymer brushes demonstrates the practicality and versatility of this novel strategy.

Two examples of a new family of water-based, nonstick, hydrophobic polymeric coatings were used to relate wettability to surface composition and adhesion. They were prepared by cross-linking reactive perfluoroalkyl polymeric surfactants, RPPSs, with poly(2-isopropenyl-2-oxazoline). Wettability may be manipulated by varying chemical composition, curing conditions, and degree of cross-linking. Low wettability and nonstick properties result from self-assembly of RPPS-containing chains, surface density and extent of orientation of perfluoroalkyl (R F) groups, and subsequent immobilization by conversion of polar-ionic functionality to covalent cross-links. The wettability was measured by obtaining advancing and receding contact angles and tilt angles of water, 0.10 N HCl, 0.10 N NaOH, and hexadecane. Hexadecane advancing angles are sensitive to R F surface concentration and orientation. Increased RF surface densities and orientation, measured by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS), respectively, are consistent with higher advancing angles. Increased amounts of cross-linking agent decrease hexadecane advancing and receding angles due to lower R F surface densities and orientations. Surface alkylation increases hexadecane contact angle hysteresis (CA hysteresis) and lowers tilt angles by converting more polar sites to less polar but more hexadecane-wettable sites. CA hysteresis appears to be related to heterogeneities of less than 1 µm, as determined by time of flight secondary ion mass spectrometry and surface penetration. Scanning force microscopy indicates that nanometer scale surface roughness is unrelated to CA hysteresis. Receding angles of water and aqueous solutions of HCl and NaOH increase with increased cross-link density, reaching a maximum at 1:1 mole ratio of cross-linking functionalities. Residual COOH groups cause contact angles to decrease with increasing pH. Surface alkylation decreases aqueous CA hysteresis by rendering accessible polar sites less polar and thus less water wettable. Increased cross-linking decreases CA hysteresis by decreasing the difference between wettable and nonwettable areas and ease of penetration of liquid into the surface phase. Low intrinsic adhesion is obtained when surfaces exhibit not only high hexadecane and aqueous receding angles but also low CA hysteresis.

Ein einfacher Zugang zu gemusterten 3D‐Polymerbürsten basiert auf einer durch sichtbares Licht angeregten radikalischen Polymerisation. Die zeitliche und örtliche Kontrolle der Polymerisation ermöglicht die Musterung der Polymerbürsten ausgehend von einer einheitlichen Initiatorschicht durch eine einfache Photomaske (siehe Bild). Durch Änderung der Lichtintensität können unter anderem gemusterte Polymerblöcke und komplexe 3D‐Strukturen aufgebaut werden.

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