Polymer Brushes for Molecular Transport - Paul Braun Research ...

3.3 Results...............................................................................................................................35
3.3.1 XPS characterization................................................................................................36
3.3.2 FTIR characterization of PNIPAAm brushes ..........................................................37
3.3.3 X-ray reflectometry of PNIPAAm brushes..............................................................38
3.3.4 AFM of patterned PNIPAAm brushes.....................................................................39
3.3.5 Thickness and contact angle measurements ............................................................41
3.3.6 Thermal response of PNIPAAm brushes.................................................................42
3.3.7 Fluorescence studies ................................................................................................43
3.3.7.1 Fluorescence spectroscopy and fluorescence microscopy..............................43
3.3.7.2 FRAP in unpatterned PNIPAAm brushes.......................................................44
3.3.7.3 FRAP in patterned PNIPAAm brushes...........................................................45
3.4 Discussion.........................................................................................................................46
3.5 Conclusions.......................................................................................................................52
3.6 References.........................................................................................................................53
CHAPTER 4: DIFFUSION OF PRODAN IN POLY(OLIGOETHYLENE GLYCOL
ACRYLATE) BRUSHES.....................................................................................56
4.1 Introduction.......................................................................................................................56
4.1.1 PEO used in ion transport applications....................................................................56
4.1.2 PEO for biomedical applications .............................................................................58
4.1.3 Oligoethylene glycol containing polymer brushes ..................................................59
4.1.4 Poly(oligoethylene glycol acrylate) brushes for molecular transport......................59
4.2 Experimental.....................................................................................................................60
4.2.1 Materials ..................................................................................................................60
4.2.2 Instrumentation ........................................................................................................60
4.2.3 POEGA brush formation and patterning..................................................................61
4.2.3.1 Unpatterned brush formation ..........................................................................61
4.2.3.2 Patterning of POEGA brush............................................................................62
4.2.4 Characterization of POEGA brushes .......................................................................63
4.3 Results and Discussion .....................................................................................................63
4.3.1 XPS, FTIR and ToF SIMS characterizations...........................................................63
4.3.2 Water contact angle measurements..........................................................................65
4.3.3 Thickness measurements .........................................................................................66
4.3.3.1 POEGA brushes in dry state and water-submerged state ...............................66
4.3.3.2 POEGA brush saturated with water vapor......................................................68
4.3.4 Fluorescence studies of unpatterned POEGA brushes.............................................69
4.3.4.1 Fluorescence spectroscopy of Prodan in POEGA brush.................................69
4.3.4.2 Diffusion of Prodan in POEGA brush ............................................................70
4.3.4.3 Comparison of diffusion coefficients by FRAP experiments and
calculations based on Williams-Landel-Ferry (WLF) equation .....................73
4.3.5 Patterned POEGA brushes via microcontact printing method ................................74
4.3.5.1 AFM of the patterned POEGA brushes ..........................................................74
4.3.5.2 Diffusion of Prodan in the patterned POEGA brushes ...................................77
4.3.6 Patterned POEGA brushes via photolithography and reactive ion etching .............78
4.3.6.1 AFM of the patterned POEGA brushes ..........................................................78
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