Microphase-Separated PE/PEO Thin Films Prepared by Plasma-Assisted Vapor Phase Deposition

Abstract

Immiscible polymer blends tend to undergo phase separation with the formation of nanoscale architecture which can be used in a variety of applications. Different wet-chemistry techniques already exist to fix the resultant polymeric structure in predictable manner. In this work, an all-dry and plasma-based strategy is proposed to fabricate thin films of microphase-separated polyolefin/polyether blends. This is achieved by directing (-CH2-)100 and (-CH2-CH2-O-)25 oligomer fluxes produced by vacuum thermal decomposition of poly(ethylene) and poly(ethylene oxide) onto silicon substrates through the zone of the glow discharge. The strategy enables mixing of thermodynamically incompatible macromolecules at the molecular level, whereas electron-impact-initiated radicals serve as cross-linkers to arrest the subsequent phase separation at the nanoscale. The mechanism of the phase separation as well as the morphology of the films is found to depend on the ratio between the oligomeric fluxes. For polyolefin-rich mixtures, polyether molecules self-organize by nucleation and growth into spherical domains with average height of 22 nm and average diameter of 170 nm. For equinumerous fluxes and for mixtures with the prevalence of polyethers, spinodal decomposition is detected that results in the formation of bicontinuous structures with the characteristic domain size and spacing ranging between 5 × 10(1) -7 × 10(1) nm and 3 × 10(2)-4 × 10(2) nm, respectively. The method is shown to produce films with tunable wettability and biologically nonfouling properties.

Nanophase‐separated poly(acrylic acid)/poly(ethylene oxide) plasma polymers for the spatially localized attachment of biomolecules

“…The chemical composition of the ppPEO films and ppAA NPs was analyzed by XPS (Figure and Table ). Similar to the earlier findings, ppPEO is able to retain the ether groups of the original PEO structure, and the ether group content reaches 78 at.% for these specific conditions (Figure a). Smaller contribution from the C–C– and the C═O‐based groups is related to the formation of cross‐links and insignificant chemical transformations that occur during the plasma polymerization process.…”

“…In the plasma polymerization community, microscale patterning was done typically by the sequential deposition of two different films using a mask . Our group has also shown that plasma copolymers demonstrating nanoscale phase separation can be produced by the plasma‐assisted vapor‐phase codeposition of two immiscible polymers . The method takes advantage of the ability of certain polymers to decompose thermally under vacuum, which releases oligomers .…”

Hydrolysis of PLA-like Plasma Polymer Films with Varying Degree of Crosslinking

“…Plasma polymerization from a thermally degraded solid polymer (plasma-assisted vacuum thermal evaporation) is most directly related to classical Physical Vapour Deposition (PVD) processes, but it utilizes plasma in the second step of the process. Long fragments of partially thermally decomposed bulk polymer fly through low-pressure plasma and they form a plasma polymer [9][10][11][12][13]. This method is able to produce thin films with relatively easily controllable cross-linking degree, as was demonstrated e.g.…”

“…Most often, PLA is synthetised by polycondensation of D-or Llactic acid or from ring opening polymerization of lactide, a cyclic dimer of lactic acid [3], however other synthetic methods have been also studied [4][5][6]. Lowtemperature plasma based methods have proven to be very effective for fabrication of ultrathin, pinhole-free, polymeric and nanocomposite coatings [7][8][9].…”

“…on PEG/PEO-like (polyethylene glycole/polyethylene oxide) films that otherwise needs bonding with crosslinking molecule if produced by wet chemistry processes. The thermal degradation occurs by random chain scission reactions, depolymerization, oxidative degradation, intramolecular and intermolecular transesteri-fications, hydrolysis, pyrolytic elimination and radical reactions [9]. This deposition technique can adapt large variety of precursors ("source" polymers).…”