ATOM TRANSFER RADICAL POLYMERIZATION FROM PLASMACHEMICAL NANOFILMS

Surface tethered bottle-brush co-polymers are prepared by ATRP grafting of the macroinitiator brush backbone onto plasmachemical deposited poly(vinylbenzyl chloride) initiator nanofilms, followed by ATRP growth of the side chains (bristles). Lateral force scanning probe microscopy demonstrates that poly(glycidyl methacrylate)-graft-poly(sodium 4-styrenesulfonate) bottle-brush decorated surfaces give rise to an enhancement in lubrication. Patterned polymer brushes are fabricated using molecular scratchcard lithography, where a functional top nanolayer (acting as a resist) is selectively removed using a scanning probe tip to expose underlying ATRP initiator sites. The lateral spreading of grafted polymer brush patterns across the adjacent functional resist surface is reversibly actuated by solvent exposure. Macroporous poly(vinylbenzyl chloride) scaffolds are used for ATRP initiation to generate polymer brushes and thereby actuate pore size. These functionalised macroporous scaffolds are fabricated by a decoupled two-step approach comprising plasmachemical deposition of the host material followed by spontaneous emulsion formation using amphiphilic species. Finally, charge nanopatterning onto polymer film surfaces is accomplished by using an SPM probe tip to create localised corona discharge electrification. The efficacy of surface charging is shown to correlate strongly to the polymer substrate hydrophilicity. Localised plasma generation using a scanning probe microscope tip is then demonstrated to actuate the movement of ATRP surface grafted polyelectrolyte and polyzwitterionic brushes. The raising or retraction of polymer brushes can be controlled by varying the SPM tip polarity

Molecularly controlled epoxy network nanostructures

AbstractEpoxy thermosets continue to be used in a variety of coatings, adhesives, and structural composites. Nanostructural heterogeneities have been proposed to determine the physical properties of these materials, but the presence and origin of these features is disputed. Here, we combine nano-chemical imaging and nano-thermal analysis to establish a connection between internal crosslinking and the appearance of nanoscale chemical heterogeneities in epoxy resins. Deflection of an AFM probe is used as a local sensor to detect photothermal expansion in response to infrared excitation, and nanoscale lateral variations are detected in response to illumination at wavenumbers associated with crosslinking. Furthermore, these heterogeneous chemical features correspond to an increased range of local thermal transitions, and only arise within highly cross-linked resins; lightly cross-linked specimens are found to be homogeneous