Molecular Recoiling in Polymer Thin Film Dewetting

Abstract

The molecular recoiling force stemming from nonequilibrium chain conformation was found to play a very important role in the dewetting stability of polymer thin films. Correct measurements and inclusion of this molecular force into thermodynamic consideration are crucial for analyzing dewetting phenomena and nanoscale polymer chain physics. This force was measured using a simple method based on contour relaxation at the incipient dewetting holes. The recoiling stress was found to increase dramatically with molecular weight and decreasing film thickness. The corresponding forces were calculated to be in the range from 9.0 to 28.2 mN/m, too large to be neglected when compared to the dispersive forces (approximately 10 mN/m) commonly operative in thin polymer films.

Electric field induced microstructures in thin films on physicochemically heterogeneous and patterned substrates

“…Dewetting 1-50 and electric field induced instabilities of thin liquid layers [89][90][91][92][93] and bilayers [48][49][50][81][82][83][84][85][86][87][94][95][96] have emerged as promising techniques for mesoscale pattern formation. Large-area ordered polymer patterns find diverse applications in the fabrication of micro-and optoelectronic devices, biosensors, microfluidic devices and fuel and solar cell technologies.…”

Viscoelastic Thin Polymer Films under Transient Residual Stresses: Two-Stage Dewetting on Soft Substrates

“…One of the striking revelations discovered in these recent experiments is the surprisingly large magnitude of the molecular recoiling force, which can amount up to several times the capillary force [18,20]. In the here presented dewetting experiments, we attempt to temporarily store part of the corresponding energy in the form of deformation energy of an elastic substrate and so try to make the magnitude of these stresses visible.…”

“…It was already demonstrated previously [13,18,20] that residual stresses resulting from film preparation can be significantly larger than capillary forces and, at times shorter than rep , are responsible for the formation of highly asymmetric rims in elastically deformed polymer films. These rims were much larger than ones generated by capillary forces alone [15,16].…”

“…The stability of ultrathin polymer films on various substrates has attracted broad interest due to their ubiquitous applications in numerous fields and the possibility of unveiling molecular processes and the corresponding physics that govern the behavior of polymers under confinement [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. On nonwettable substrates, such ultrathin films (thickness, h < 100 nm) may undergo dewetting driven by capillary (intermolecular) forces [1][2][3][4][5][6][7][8][9][10][11][12][13] and residual stresses within these films [14 -21].…”

“…As a first approximation, the substrate depression (D), measured inside the hole (see Fig. 3), can be considered as a direct indicator of the local strain in the PDMS layer inside the hole, from which the total dewetting force exerted on the film can be estimated [15][16][17][18][19][20]. As shown in Fig.…”