Large scale alignment of a lamellar block copolymer thin film via electric fields: a time-resolved SFM study

Scanning Force Microscopy as Applied to Conformational Studies in Macromolecular Research

“…[240,241] Time evolution of dynamics of surface relief and phase transition in the structure of block copolymer films were studied upon exposure to vapours [242,243] and also with additionally applied electric field. [244,245] Is was shown that different vapours may destabilise and induce dewetting of thin [246,247] and ultrathin-i.e., with thicknesses smaller than the radius of gyration of the unperturbed molecule R g [248] -polymer films. [249,250] Finally, there is clear understanding now in the literature that the balance of interaction between the substrate and the adsorbed molecules can be finely tuned through the choice of the proper solvent to be used in the vapour exposure in order to promote directed reorganisation and self-assembly.…”

Effects of Electric Fields on Block Copolymer Nanostructures

“…For the electric field studies, films of the respective block copolymers with lamellar orientations perpendicular to the substrate were prepared as reported earlier. This resulted in film thicknesses (d) of 37 ± 2 nm for S 47 H 10 M 43 82 and 745 ± 2 nm for S 50 V 50 78 [9,17,19]. In order to study the influence of the electric field strength on the degree of alignment, ex situ experiments with gradient gold electrodes on a glass substrate were performed.…”

“…Two lamellar block copolymers will now be discussed. Polystyrene-blockpoly(2-hydroxyethyl methacrylate)-block-poly(methyl methacrylate) [S 47 H 10 M 43 82 ; consisting of 47 wt% polystyrene (PS), 10 wt% poly(2-hydroxyethyl methacrylate) (PHEMA) and 43 wt% poly(methyl methacrylate) (PMMA) with a total numberaverage molecular weight (M n ) of 82 kg/mol] and polystyrene-block-poly(2-vinyl pyridine) (S 50 V 50 78 ; consisting of 50% PS and 50% PVP with M n of 78 kg/mol) were synthesized by sequential living anionic polymerization as described in detail elsewhere [9,12,17]. The static dielectric constants of the PS, PMMA, and PVP were 2.4, 3.6, and 7.5, respectively [18].…”

Electric field manipulated nanopatterns in thin films of metalorganic 3-miktoarm star terpolymers

“…The ordering and morphological behavior of the diblock copolymers exhibit two effects of an electric field: an increase in the volume fraction of the PFEMS block by oxidation of the ferrocenyl groups leading to a morphological transformation, and orientation of the dielectric interfaces parallel to E. Microdomains of 3-miktoarm star terpolymers exhibit ordering and a sequence of phase transitions with increasing electric field strength. At moderate field strengths the observed phase transitions can be attributed to the electrostatic energy penalty associated with dielectric interfaces not aligned parallel to E. [20][21][22][23][24][25][26][27][28] At higher electric field strengths the electroactive response of the PFEMS block becomes the dominant factor determining the morphological transition. Such dual responsive behavior facilitates structural switchability and provides a high degree of ordering upon application of electric field stimuli.…”

“…The basic concept determining the behavior of non-metalcontaining block copolymers in electric fields is the unfavorable electrostatic energy of block-block interfaces oriented perpendicular to the electric field vector ( E) with respect to those aligned parallel to E. Electric-field-induced ordering and defect annihilation have been thoroughly investigated since the work of Amundson et al in 1991. [19][20][21][22][23][24][25][26][27][28] Reorientation of dielectric interfaces parallel to the electric field vector is the anticipated response when a certain threshold voltage, dependent on the polymer and annealing conditions, is exceeded.…”