-
[show abstract]
[hide abstract]
ABSTRACT: Patterned polymer structures with different functionalities have many potential applications. Directed assembly of polymer blends using chemically functionalized patterns during spin-coating has been used to fabricate the patterned polymer structures. For bridging the gap between laboratorial experiments and manufacturing of nanodevices, the polymer blends structures are required to be precisely patterned into nonuniform geometries in a high-rate process, which still is a challenge. In this Article, we demonstrated for the first time that by decreasing the interfacial tension between two polymers polystyrene and poly(acrylic acid) via adding a compatibilizer (polystyrene-b-poly(acrylic acid) ), a polystyrene/poly(acrylic acid) blend was precisely patterned into nonuniform geometries in a high-rate fashion. The patterned nonuniform geometries included angled lines with angles varied from 30° to 150°, T-junctions, square arrays, circle arrays, and arbitrary letter-shaped geometries. The reduction in the interfacial tension improved the line edge roughness and the patterning efficiency of the patterned polymer blends. In addition, the commensurability between characteristic length and pattern periodicity for well-ordered morphologies was also expanded with decreasing interfacial tension. This approach can be easily extended to other functional polymers in a blend and facilitate the applications of patterned polymer structures in biosensors, organic thin-film electronics, and polymer solar cells.
Langmuir 05/2012; 28(27):10238-45. · 4.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Poly�methyl methacrylate� �PMMA� substrates were ablated through a fast femtosecond �fs� laser
scanning process to create patterns for enhanced protein binding. Typically, two patterns with lines
and grids were produced and the protein binding was evaluated by studying the adsorption of
fluorescein isothiocyanate �FITC�-labeled bovine serum albumin �BSA�. It was found that the
adsorption of FITC-BSA was increased up to tenfold on both patterns compared with the untreated
PMMAsurface, indicating the potential application of the fs laser ablated PMMAsurfaces as protein
assay substrates.
Applied Physics Letters 04/2011; 98:171101. · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: a b s t r a c t The directed self-assembly of polymer-polymer-solvent ternary blends on heterogeneously functional-ized substrate is investigated with a three dimensional numerical model. The numerical simulation results are quantitatively verified by the experimental results. The phase separation of PS-PMMA-DMF blends are spin coated on a substrate functionalized by ODT/NH 2 on Au surface. While many simulation parameters are set to the experimental conditions, other unmeasurable material constitutive model parameters are estimated from the real experiment observations. The effects of the spin speed, pattern periodicity, PS/PAA composition ratio, and the PAA molecular weight are investigated in both the experiments and numerical simulation. The simulation results are verified by comparison to the experimental results. During the verification process, numerical optimization methods are employed to determine the unmeasurable physical parameters. Quantitative methods are introduced for assessment of the results.
02/2011;
-
[show abstract]
[hide abstract]
ABSTRACT: Directed assembly of polymer blends using chemically heterogeneous patterns during spin-coating can be used to produce nanopatterned polymer structures. Well-ordered morphologies are obtained when the characteristic length of a polymer blend is commensurate with pattern periodicity. In this paper, spin-coating speed and solution concentration were used to control the characteristic length of a polystyrene (PS)/poly(acrylic acid) (PAA) blend. With increasing spin speed or reducing solution concentration, the characteristic length decreased. Critical spin speeds or solution concentrations that produced the required characteristic length commensurate with the given pattern periodicity were predicted. Well-ordered morphologies were obtained when spin speed or solution concentration was close to the critical value. A new method of image analysis was introduced to quantitatively evaluate the quality of replication of the underlying pattern. The range of commensurability between characteristic length and pattern periodicity for well-ordered morphologies was investigated. When the range of commensurability was within 20%, well-ordered morphologies were produced.
11/2010;
-
Macromolecular Materials and Engineering 07/2010; 295(8):701 - 708. · 1.99 Impact Factor
-
Small 11/2009; 5(24):2788-91. · 8.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: a b s t r a c t Block copolymers are of increasing interest because of their nanometer-scale morphologies, which can be utilized in a range of applications, including nanolithography. Orientation of the domains can be controlled by part design and processing conditions in injection molding. In this work the surface morphology and alignment of block copolymers by mechanical flow fields from injection molding was investigated using a styrene–ethylene/butylene–styrene triblock copolymer (SEBS) and compared with the morphology induced by spin coating. Compared with the isotropic morphology found by spin coating and annealing, the surface domains were oriented in the flow direction. Increasing mold temperature and injection velocity enhanced the degree of orientation, whereas melt temperature had little effect. Smaller characteristic lengths were produced with higher mold temperatures and injection velocities.
10/2009;
-
[show abstract]
[hide abstract]
ABSTRACT: A unique interaction has been found between protein G' (a truncated recombinant bacterial "alphabet" protein which aligns by noncovalent attachment to the antibody stem) and poly(methyl methacrylate), a thermoplastic polymer substrate, which can be easily fabricated using high-rate processes. Significantly improved orientation efficiency with traditional passive adsorption for this system (termed ALYGNSA) has been achieved as compared to the same assay performed on a polystyrene substrate with protein G'. Results were consistent with an average alignment of 80% of the human immunoglobulin G capture antibody which translated into a 30% to 50% improved alignment over an array of industry standards tested. Laser scanning confocal microscopy confirmed the immunological results. Studies of additional poly(methyl methacrylate) polymer derivatives and protein biolinker (A and AG) combinations have been conducted and have revealed different degrees of antibody alignment. These findings may lead to additional novel noncovalent methods of antibody orientation and greater sensitivity in immunological assays.
Analytical and Bioanalytical Chemistry 01/2009; 393(5):1531-8. · 3.78 Impact Factor
-
Advanced Materials 12/2008; 21(7):794 - 798. · 13.88 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The spinodal phase decomposition of an immiscible binary polymer blend system is investigated with numerical models in two-dimensional and three-dimensional (3D). The effect of the elastic energy is included. The mechanism of the evolution of the phase separation is studied and the characteristic length R(t) is shown to be proportional to t(13). In the case when the phase separation is directed by a heterogeneously functionalized substrate, the increase in the characteristic length is divided into two stages by a critical time. The R(t) approximately t(13) diagram can be fitted with a straight line in both the first and second stages. The slope of the fitting line significantly decreases after the critical time. The compatibility of the resulting pattern to the substrate pattern is also measured by a factor C(S). It is observed that there is also a critical time in the evolution of the compatibility for the cases with and without elastic energy. The critical time of C(S) is identical with the respective critical time of R(t). The lateral and vertical composition profiles functionalized substrate is observed with the 3D model. The difference mechanism of the cases with and without elastic energy is discussed.
The Journal of chemical physics 07/2008; 128(22):224909. · 3.09 Impact Factor
-
Macromolecular Rapid Communications 11/2006; 27(21):1826 - 1832. · 4.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Phase separation of an asymmetric immiscible binary polymer system in an elastic field with the existence of a patterned substrate was numerically studied in 2D and 3D. An unconditionally stable method for time marching the Cahn-Hilliard equation was employed in the numerical simulation. Compare to the conventional interface tracing mechanism, this diffusion controlled system is characterized by the thick interface with composition gradient. The evolution mechanisms were studied. It can be observed that the The characteristic length, R(t), of the phase separation morphology patterns was measured with Fast Fourier Transform method. The power law of increase of R(t) was investigated. In our numerical study R(t) 1/3 increased linearly with time. The influence of the material composition, the attraction factor on the template and the gradient energy coefficient between the two polymers on the result patterns were also observed in this study. The analytical results were compared with experiment. Qualitative and quantitative correspondence can be observed between the numerical results and the experiment results.
-
[show abstract]
[hide abstract]
ABSTRACT: The spinodal decomposition of a polymer-polymer-solvent ternary system was investigated in a 3-dimensional numerical model. The Cahn-Hilliard equation was employed to describe the free energy profile of the domain. A heterogeneously func-tionalized substrate was also implemented into the model to sim-ulate the effect of substrate attraction. The mechanism of the morphology evolution was studied quantitatively. The well estab-lished linear relationship of the characteristic length, R(t) with t 1 3 can be observed in the simulation results. The compatibility of the result pattern and the pattern on the substrate was measured by a scalar, C s . The influence of the solvent concentration on the refinement of the result pattern was studied in this work. A crit-ical time can be observed from the evolution of the value of C s . The morphology evolution of a system considering the solvent evaporation was also studied. INTRODUCTION The polymer self-assembly directed by the heterogeneously functionalized substrate can be used to replicate the polymer products with features in nano scales, which can be used in many fields including lithographic processes, biosensors, and semicon-ductor devices [1, 2].The phase separation of polymer blends di-rected by patterned substrate has been extensively studied [3–7].
-
-
-
Jason Chiota, John Shearer, Ming Wei, Carol Barry, Joey Mead
