Processing of the Multifunctional Polymer Poly(phenylene methylene) into Fibers, Films, Foams, and Microspheres

Abstract

Poly(phenylene methylene) (PPM) has recently emerged as a promising multifunctional polymer, requiring straightforward one‐step synthesis to achieve high molar mass and featuring a range of attractive properties. Its processability, however, has not been explored in detail to date. Therefore, this study presents a comprehensive investigation of the processability of PPM into a wide range of forms by employing various polymer processing techniques. Thin fibers (diameter ≈100 µm) over 1 km in length and shorter thick fibers (diameter ≈1 mm) are produced by melt spinning. Although no crystallinity is observed, the fibers surprisingly exhibit pronounced birefringence. The capability for waveguiding red light within the fibers is also demonstrated. Furthermore, films with a broad thickness range, spanning nanometer to millimeter length scales, are fabricated using different approaches such as spin‐coating, hot pressing, and die casting. All films feature a very smooth and crack‐free surface topography. Additionally, freestanding foams of PPM are obtained by foaming highly concentrated solutions, and quasi‐monodisperse microspheres are prepared by a microfluidic high‐throughput emulsification. The material properties of these different specimen forms are investigated and discussed for implementation as products ranging from plastic optical fibers and light emitting diodes, to protective coatings and packaging, as well as insulators and separation membranes.

Homoconjugation in Light-Emitting Poly(phenylene methylene)s: Origin and Pressure-Enhanced Photoluminescence

“…Polarized Raman and PL Spectroscopy. Following the recent report of straightforward fabrication of PPM fibers by melt-drawing, 9 PPM and PTMPM fibers were studied by polarized spectroscopy to further explore the interplay between the intrachain structure and photophysics, the nuances of which typically are obscured by molecular disorders isotropic samples. Cross-polarized microscopy of the obtained fibers (inset of Figure 4a) indicates pronounced linear birefringence, confirming the anisotropic chain orientation, which, with only rare exceptions, 39 is expected to be parallel to the fiber axis.…”

“…The latest reports highlighted its high decomposition temperature (470 C under ambient atmosphere), 2 excellent resistance to oxidizing agents, 3 attractive barrier properties and high hydrophobicity. 4 With recent reports having disclosed robust, one-step synthesis for yielding high molar mass materials in large volume, [5][6][7][8] and combined with its excellent processability, 4,9 PPM and its derivatives are proposed for a variety of advanced applications in, e.g., corrosion-resistant coatings, plastic optical fibers and encapsulating laminates. 4,9,10 Arguably, the most remarkable characteristics of PPM are its optical properties, that is photoluminescence (PL) in the 400-600 nm spectral region, with solid-state PL quantum efficiency  41% and PL lifetime >8 ns.…”

“…4 With recent reports having disclosed robust, one-step synthesis for yielding high molar mass materials in large volume, [5][6][7][8] and combined with its excellent processability, 4,9 PPM and its derivatives are proposed for a variety of advanced applications in, e.g., corrosion-resistant coatings, plastic optical fibers and encapsulating laminates. 4,9,10 Arguably, the most remarkable characteristics of PPM are its optical properties, that is photoluminescence (PL) in the 400-600 nm spectral region, with solid-state PL quantum efficiency  41% and PL lifetime >8 ns. 2,11 These observations for PPM and its methyl-substituted derivatives 2,11 are especially fascinating given the absence of direct-conjugation along the polymer backbone due to an electronically 'insulating' methylene group separating adjacent phenylene groups.…”

“…The latest reports highlighted its high decomposition temperature (∼470 °C under ambient atmosphere), excellent resistance to oxidizing agents, attractive barrier properties, and high hydrophobicity . With recent reports having disclosed robust, one-step synthesis for yielding high molar mass materials in large volume, − and combined with its excellent processability, , PPM and its derivatives are proposed for a variety of advanced applications in, for example, corrosion-resistant coatings, plastic optical fibers, and encapsulating laminates. ,, …”

Visible Light Induced Conventional Step‐Growth and Chain‐Growth Condensation Polymerizations by Electrophilic Aromatic Substitution

“…As they have no direct π –conjugation, the observed PL activity is due to the homoconjugation along the polymer chain. [ 38 ] Such properties make PPMs as alternative candidates for corrosion resistant coatings, optical fibers and laminates. [ 39 ]…”