The controlled nitroxide-mediated homopolymerization of 9-(4-vinylbenzyl)-9H-carbazole (VBK) and the copolymerization of methyl methacrylate (MMA) with varying amounts of VBK were accomplished by using 10 mol % {tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino} nitroxide relative to 2-({tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]ami-no}oxy)-2-methylpropionic acid (BlocBuilder TM ) in dimethylformamide at temperatures from 80 to 125 C. As little as 1 mol % of VBK in the feed was required to obtain a controlled copolymerization of an MMA/VBK mixture, resulting in a linear increase in molecular weight versus conversion with a narrow molecular weight distribution (M w /M n % 1.3). Preferential incorporation of VBK into the copolymer was indicated by the MMA/VBK reactivity ratios determined: r VBK ¼ 2.7 6 1.5 and r MMA ¼ 0.24 6 0.14. The copolymers were found significantly ''living'' by performing subsequent chain extensions with a fresh batch of VBK and by 31 P NMR spectroscopy analysis. VBK was found to be an effective controlling comonomer for NMP of MMA, and such low levels of VBK comonomer ensured transparency in the final copolymer.

The effects of ice formation and accretion on external surfaces range from being mildly annoying to potentially life-threatening. Ice-shedding materials, which lower the adhesion strength of ice to its surface, have recently received renewed research attention as a means to circumvent the problem of icing. In this work, we investigate how surface wettability and surface topography influence the ice adhesion strength on three different surfaces: (i) superhydrophobic laser-inscribed square pillars on copper, (ii) stainless steel 316 Dutch-weave meshes, and (iii) multiwalled carbon nanotube-covered steel meshes. The finest stainless steel mesh displayed the best performance with a 93% decrease in ice adhesion relative to polished stainless steel, while the superhydrophobic square pillars exhibited an increase in ice adhesion by up to 67% relative to polished copper. Comparisons of dynamic contact angles revealed little correlation between surface wettability and ice adhesion. On the other hand, by considering the ice formation process and the fracture mechanics at the ice-substrate interface, we found that two competing mechanisms governing ice adhesion strength arise on nonplanar surfaces: (i) mechanical interlocking of the ice within the surface features that enhances adhesion, and (ii) formation of microcracks that act as interfacial stress concentrators, which reduce adhesion. Our analysis provides insight toward new approaches for the design of ice-releasing materials through the use of surface topographies that promote interfacial crack propagation.

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9-(4-Vinylbenzyl)-9H-carbazole (VBK) was used as the "controlling" comonomer for nitroxide mediated polymerization with 10 mol % SG1 free nitroxide relative to BlocBuilder initiator at 80 °C of oligo(ethylene glycol) methyl ether methacrylate (8−9 ethylene glycol (EG) units) (OEGMA 8−9 ), 2-(2-methoxyethoxy)ethyl methacrylate (MEO 2 MA) and for an OEGMA 8−9 /MEO 2 MA-mixed feed. The synthesis of MEO 2 MA/VBK and OEGMA 8−9 /VBK copolymers and MEO 2 MA/OEGMA 8−9 /VBK terpolymers exhibited linear increases in number-average molecular weight (M̅ n ) versus conversion X, up until X = 0.6, with final copolymers characterized by relatively narrow, monomodal molecular weight distributions (M̅ w /M̅ n < 1.4, in most cases). A series of MEO 2 MA/OEGMA 8−9 /VBK terpolymers were synthesized and by varying the OEGMA 8−9 :MEO 2 MA feed ratios, the terpolymers exhibited tunable lower critical solution temperatures in water (28 °C < LCSTs < 81 °C). MEO 2 MA/OEGMA 8−9 / VBK terpolymers were deemed sufficiently pseudo-"living" to reinitiate a second batch of MEO 2 MA/OEGMA 8−9 /VBK, with few apparent dead chains, as indicated by the monomodal shift in the GPC chromatograms. The resulting MEO 2 MA/OEGMA 8−9 / VBK block copolymers were designed so that each block exhibited a distinct LCST, which was confirmed by UV−vis and dynamic light scattering. In addition to controlling the terpolymerization, the VBK units imparted thermo-responsive fluorescence into the final copolymers.

The majority of studies performed on the formation of surface features by femtosecond laser radiation focuses on single scan procedures, i.e. solely manipulating the laser beam once over the target area to fabricate different surface topographies. In this work, the effect of scanning stainless steel 304 multiple times with femtosecond laser pulses is thoroughly investigated over a wide range of fluences. The resultant laserinduced surface topographies can be categorized into two different regimes. In the low fluence regime (F Σline,max < 130 J/cm 2 ), ellipsoidal cones (randomly distributed surface protrusions covered by several layers of nanoparticles) are formed. Based on chemical, crystallographic, and topographical analyses, we conclude that these ellipsoidal cones are composed of unablated steel whose conical geometry offers a significant degree of fluence reduction (35-52%). Therefore, the rest of the irradiated area is preferentially ablated at a higher rate than the ellipsoidal cones. The second, or high fluence regime (F Σline,max > 130 J/cm 2 ) consists of laser-induced surface patterns such as columnar and chaotic structures. Here, the surface topography showed little to no change even when the target was scanned repeatedly. This is in stark contrast to the ellipsoidal cones in the first regime, which evolve and grow continuously as more laser passes are applied. Keywords