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Block copolymer (BCP) thin films have shown high potential as a pattern transfer medium for ultra-fine (<20 nm) features. We introduce an effective approach for performing rapid local annealing of BCP films by focused laser spike (FLaSk) zone annealing, using a moving highly-focused circularly polarized visible wavelength laser spot. A poly(styrene-b-dimethylsiloxane) BCP was transformed from a...
The tensile and compressive properties of triptycene-polycarbonates were tested over 6 orders of magnitude in strain rate. Initially we studied a low molecular weight, low triptycene content PC blended with Iupilon ® PC and then a series of higher molecular weight, higher triptycene content polymers. The PC blend with only 1.9wt% triptycene displayed up to 20% increase in modulus and up to...
Polypyrrole is a leading conducting polymer actuator, but the factors that influence its performance when actuated under load in devices (such as the polymer stiffness) are not yet fully understood. To this end, we have probed the dynamic elastic modulus of polypyrrole in situ during actuation in a variety of electrolytes. As part of this study, we demonstrate that the electroactive response in dilute...
Free-standing polypyrrole films have been stretched or cold rolled to produce uniaxially and biaxially textured films. The oriented films show an increase in conductivity up to 3× when compared to unprocessed films, due to polymer chain alignment. Highly anisotropic active stress and strain are observed for the textured films, with up to 7× larger active strains transverse to the orientation direction...
A poly(l-lactic acid)-block-polystyrene-block-poly(methyl methacrylate) (PLLA-b-PS-b-PMMA) triblock copolymer was synthesized with a crystalline PLLA end block. Single crystals of this triblock copolymer grown in dilute solution could generate uniformly tethered diblock copolymer brushes, PS-b-PMMA, on the PLLA single crystal substrate. The diblock copolymer brushes exhibited responsive, characteristic...
A poly(ethylene oxide)-b-polystyrene (PEO-b-PS) diblock copolymer with a number average molecular weight of PEO blocks, MnPEO=8.8kg/mol, and a number average molecular weight of PS blocks, MnPS=24.5kg/mol, (volume fraction of the PEO blocks, f PEO , was 0.26) exhibited a hexagonal cylinder (HC) phase structure. Small angle X-ray scattering results showed that the PEO cylinder diameter was...
The hierarchical microstructure responsible for the unique energy-absorbing properties of natural materials, like native spider silk and wood, motivated the development of segmented polyurethanes with soft segments containing multiple levels of order. As a first step in correlating the effects of crystallinity in the soft segment phase to the hard segment phase, we chose to examine the morphology...
A polymer blend system consisting of polystyrene grafted onto poly (p-phenylene ethynylene) (PS-g-PPE) and poly (styrene-block-isoprene-block-styrene) triblock copolymer (SIS) yields highly polarized emission due to the unidirectional alignment of the PPE molecules. During the roll casting, the triblock copolymer microphase separates and creates unidirectionally aligned PS cylindrical microdomains...
A high molecular weight polystyrene-block-polyisoprene copolymer was synthesized by anionic polymerization of styrene and isoprene monomers. Polystyrene cylindrical domains in a hexagonal lattice with relatively large periodicity and controlled orientation have been produced through roll casting of the polystyrene-block-polyisoprene copolymer with a total molecular weight of 1.0×10 6 g/mol...
Block copolymers (BCPs) have received great attention for the past 40 years but only within the past decade have they been seriously considered for nanotechnological applications. Their applicability to nanotechnology stems from the scale of the microdomains and the convenient tunability of size, shape, and periodicity afforded by changing their molecular parameters. The use of the tensorial physical...
Roll[hyphen]casting orientation of cylinder microphase separated poly(styrene[hyphen]b[hyphen]butadiene[hyphen]b[hyphen]styrene) triblock copolymers, was analyzed. The mechanical anisotropy of roll[hyphen]cast films, defined as the ratio of Young's modulus obtained parallel and perpendicular to poly(styrene) cylinders, is similar for samples prepared using a dimensionless minimum gap between rolls...
A wide variety of commercial polymeric membranes are manufactured by a non-solvent immersion precipitation process, yet the detailed mechanism and kinetics of membrane formation are poorly understood. We have used a confocal microscope, with fluorescence filters removed, to observe backscatter from precipitating nylon 6 films. Nylon 6 in formic acid/water solutions was spread on a glass substrate,...
We report the morphological characterization of asymmetric miktoarm star block copolymers of the (PS-b-PI)nPS type where n=2,3 (denoted 2DB and 3DB miktoarm stars, respectively) and a symmetric super H-shaped block copolymer of the (PS-b-PI)3PS(PI-b-PS)3 type (denoted SH) which were synthesized by anionic polymerization. The initial volume fraction of PS (φPS) for each copolymer was 0.51–0.56, giving...
A lamellae-forming poly(ethylene oxide)-b-polystyrene (EOS) has been blended with a polystyrene homopolymer (PS) and a PS oligomer (PSO), respectively, to obtain miscible polymer blends (denoted as EOS/PS-32 and EOS/PSO-32, respectively). Both blends exhibit cylindrical microphase morphologies, with the PEO volume fractions being 0.32. The order–disorder transition temperatures (T ODT ) of...
Substituted poly(paraphenylene) derivatives (PX) have recently gained interest due to their unique properties [1–5]. They are amorphous thermoplastics with relatively modest glass transition temperatures (Tg∼150°C), are soluble in various common organic solvents, and yet possess the strongest mechanical properties of any amorphous thermoplastic [6]. However, the blend behavior of these polymers is...
Transmission electron microscopy (TEM) was used to examine the morphology of extruded thermoplastic starch/poly(ethylene-vinyl alcohol) (EVOH) blends. Both the starch and EVOH polymers were found to be very beam sensitive: the maximum allowable beam dosages for the crystalline fraction of both components are estimated at less than 3.5×10 −3 Ccm −2 at 200kV and room temperature. In...
Relaxation of disclination loops created during shear flow of a low molar mass and a polymer liquid crystal were monitored using a special shear stage with a videomicroscope. Loops in the polymer system generally displayed initially highly distorted contours. In the small molecule liquid crystal, the loop contours consistently exhibited very simple, generally convex shapes. In the polymer system,...
Polystyrene-polybutadiene-polystyrene triblock copolymers were roll-cast from toluene solutions to form globally oriented films. As-processed films, containing process-related residual stresses, were exposed to solvent vapours. Three solvents were used in this study: toluene, which is a non-preferential solvent for polystyrene and polybutadiene; methyl-ethyl-ketone, which is a preferential solvent...
Polystyrene-polybutadiene-polystyrene triblock copolymers were roll-cast from toluene solutions to form globally oriented films. Microstructural changes following thermal annealing of films with cylindrical and lamellar morphology were monitored using two-dimensional small angle X-ray scattering, transmission electron microscopy and thermomechanical analysis. The microdomains in the unannealed films...
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