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Synthetic Library Fabrication Tools II
 

2. Microchannel Confined Surface Initiated Polymerization (uSIP)

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Molecular Weight Gradients (I)
By filling a channel at different flow rates, the slope of the gradient is controlled (inset), while kinetic information is identical for both rates.
 
Solution Composition Gradients (II)
The kapp of 2-hydroxyethyl methacrylate (HEMA) is dependent on solvent. In a water-methanol gradient, a molecular weight (thickness) gradient of polymer is obtained.
    
 
Statistical Copolymer Gradients (II, cont.)
If a gradient between two monomer concentrations is established (e.g. n-butyl methacrylate; nBMA and N,N-dimethylamino- ethyl methacrylate; DMAEMA), a gradient in statistical copolymer composition is obtained on the surface.
 
    
 
Patterning (III)
Stamps can be removed and reapplied. Initiation efficiency is retained in grafted areas and in previously stamp protected areas.
 
 
Micropatterning (III, cont.)
In micrometer wide channels with smaller depths (< 1 um), capillary forces quickly draw monomer solutions into the pattern.
 
      
 

3. Organic Droplet Phases as Microreactors in Microfluidic Devices
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Microfluidic devices prepared from the thiolene adhesive enable stabilization of organic droplet phases.

Droplet size and spacing can be controlled by the relative flow rates of the two phases

 
Small molecule chemistry
Following color loss during bromination of styrene enables reaction progress tracking.
  
 
Monomer droplets are polymerized using a UV spot source and characterized with Raman spectroscopy. Goals include varying droplet composition and use of arrays of particles as polymer libraries
 
Confinement of channel walls can impose asymmetry retained in final polymer particle.
     
 
 

Future Work

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Future work includes:
  • The preparation of libraries of statistical and block copolymers in solution and on surfaces using methods 1 and 2 above.
  • Preparation of combinatorial particle arrays using method 3.
  • Incorporation of additional spectroscopic and/or chromatographic characterization capabilities on chip.
  • Integration of synthetic methods with other NCMC technology including phase mapping and SPM reference materials initiatives.
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    Publications

    1
     
    T. Wu, Y. Mei, J.C. Cabral, C. Xu and K.L. Beers, "A New Synthetic Method for Controlled Polymerization using a Microfluidic System" J. Am. Chem. Soc., 2004, 126, 7880-7881.

    C. Xu, T. Wu, C. M. Drain, J. D. Batteas and K.L.Beers, “Microchannel Confined Surface Initiated Polymerization" Macromolecules, in press.

    Z. Cygan, J. T. Cabral, K. L. Beers and E. J. Amis, “Microfluidic Platform for Organic Phase Microreactors” submitted.

    K. L. Beers, J. T. Cabral, H. J. Walls, E. J. Amis, “High Throughput Measurements of Polymer Fluids for Formulations” Proc. Mater. Res. Soc., 2004, 804, JJ7.4.1.

    C. Xu, T. Wu, C. M. Drain, J. D. Batteas and K. L. Beers, “Synthesis of Gradient

    Copolymer Brushes via Surface Initiated Atom Transfer Radical

    Copolymerization,” Polym. Prepr. Am. Chem. Soc. Div. Pol. Chem., 2004,

    45(2), 667.

    T. Wu, Y. Mei, C. Xu and K. L. Beers, “Phase Transition of PDMAEMA-b-PEG in

    Aqueous Solution Dependence on Molecular Mass and Compositions,” PMSE

    Prepr. Am. Chem. Soc. Div. Pol. Chem., 2004, 91, 1006.
     

    NIST Contributors:
    1
     
    Tao Wu, Chang Xu, Zuzanna T. Cygan, Ying Mei, Kathryn L. Beers* and Eric J. Amis
     
     
     
    		 
    		 
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