Fully Isotactic Poly(p-methylstyrene): Precise Synthesis via Catalytic Polymerization and Crystallization Studies

Abstract

The synthesis of stereoregular styrenic polymers on single-site catalysts has received great attention over the last decades; however, little is known with respect to tailoring fully isotactic poly­(p-methylstyrene) (iPpMS). Here, we demonstrate that isospecific coordination polymerization of p-methylstyrene can be achieved in the presence of the catalyst dichloro­[1,4-dithiabutanediyl-2,20-bis­(4,6-di-tert-butyl-phenoxy)]titanium activated by methylaluminoxane. Moreover, iPpMS has been assumed to be noncrystallizable for decades, as X-ray diffraction and differential scanning calorimeter measurements of powder samples failed to reveal a well-defined crystal structure. However, we successfully generated dendritic crystals of iPpMS from dilute solutions by carefully controlling the evaporation rate of the solvent. The crystal morphology was studied by optical microscopy and atomic force microscopy. In situ heating experiments of dendritic crystals allowed us to measure the melting temperature of iPpMS crystals. Moreover, a vapor annealing process was carried out to prepare multilamellar crystals for small-angle X-ray scattering measurements to characterize the spacing and orientation of the formed crystalline lamellae.

Polymerization of Styrene Derivatives Using Anilinonaphthoquinone‐Ligated Nickel Complexes and Thermal/Rheological Properties of the Produced Polymers

“…The signals attributed to the aromatic protons of the PStX units are observed in the range of 6.5–7.2 ppm. [ 28–30,32–36 ] Strong methyl peaks of PStOMe and PStMe are observed at 3.7 and 2.3 ppm, respectively. [ 29,32,35,36 ]…”

“…[ 28–30,32–36 ] Strong methyl peaks of PStOMe and PStMe are observed at 3.7 and 2.3 ppm, respectively. [ 29,32,35,36 ]…”

“…The phenyl carbons of the MeSt units in the regions of 134–143 ppm and methyl carbon in the regions of 21 ppm indicate the successful polymerization of StMe (Figure 2b). [ 29,35 ]…”

“…The decrease of the polymerization temperature increased the mm triad accompanied by the decrease of the mr triad (Figures S3 and S4, Supporting Information, and Figure 3). [ 32–36 ] The highest mm values of 82% (PStOMe), 76% (PStMe), and 74% (PSt) were obtained at 0 °C (Run 22, 13 and 1 in Table 3 ).…”

Self-Seeding Procedure for Obtaining Stacked Block Copolymer Lamellar Crystals in Solution

“…To generate PS- b -PEO lamellar crystals under controlled conditions, the dispersion was subsequently heated to a seeding temperature ( was varied from 35 °C to 60 °C) and then quenched to the crystallization temperature ( was varied from 10 °C to 22 °C). We kept the solution at for 24 h to reach equilibrium, i.e., all polymers above the solubility limit were included in crystalline structures [ 16 , 42 ]. The thermal protocol shown in Figure 1 was employed for the crystallization of PS- b -PEO in solution.…”