Surface Segregation Studies of Fluorine-Containing Diblock Copolymers

Abstract

A diblock copolymer of deuterated styrene and isoprene (dPS−PI) with a small volume fraction of isoprene was chemically modified to incorporate pendant fluorinated side chains (“fingers”). The composition distribution of the diblock copolymers within a high molecular weight polystyrene (PS) homopolymer was determined by forward recoil spectrometry. Surface segregation and interfacial segregation of the modified block copolymers from a polystyrene matrix are observed in as-spun films. Equilibrium segregation was achieved on annealing at 160 °C for several days. The segregation isotherms at the air−polymer interface are shown to be quantitatively described by a self-consistent mean field theory (SCMF), and these permit us to estimate an effective Flory parameter which describes the attraction of the fluorinated segments to the surface and their repulsion from the bulk. The change in the surface tension as a result of the adsorption of the block copolymers at the air−homopolymer interface was evaluated from the predictions of SCMF theory and compared with the changes in the water contact angle observed. Advancing water contact angle data are consistent with the presence of a nonuniform layer of PS, CF2, and CF3 segments on the surface of the segregated samples.

Recent Progress in Polymer Solar Cells: Manipulation of Polymer:Fullerene Morphology and the Formation of Efficient Inverted Polymer Solar Cells

“…[141] F-PCBM preferentially segregates a layer 2 nm thick at the top surface due to the lower surface energy from the fluorinated side groups. [142] Via this approach, the FF increased to an impressively high 72%, and was mainly attributed to the surface dipole moment induced by the F-PCBM layer, which decreased the energy barrier between the Al cathode and the PCBM. Nonetheless, this device structure demonstrated an ideal vertical phase separation, with the electron-acceptor material enriched adjacent to the cathode.…”

Silica reinforced triblock copolymer gels

“…Changing the chemical nature of one or both the component blocks can have dramatic effects on the self-assembly of the resultant material. Modification of the polydiene block in polystyrene-polydiene-polystyrene block copolymers has received much attention [35][36][37][38][39][40][41], including the selective hydrogenation of the midblock. Because the transition temperature from a rubbery gel to a plastic fluid (T P ) is too low for many applications, polystyrene has been either replaced by a higher T g block [42][43][44][45] or chemically modified [46][47].…”

Self‐Organized Buffer Layers in Organic Solar Cells

“…It is well-known that materials having a low surface energy such as fluorinated or silicone compounds prefer to migrate to the air/liquid interface during coating. [7][8][9][10] This is called surface segregation, which is driven by the total energy minimization of the system. On the basis of the idea to utilize this phenomenon, we designed and synthesized a novel fullerene derivative with a fluorocarbon chain (F-PCBM), as shown in Figure 1a.…”