Structural analysis of PPX prepared by vapor phase pyrolysis of [2.2]paracyclophane

Abstract

Poly(p‐xylylene) (PPX) was prepared by vapor phase pyrolysis of [2.2]paracyclophane following the procedure of Gorham. PPX was obtained in different crystalline modifications by dry annealing, dissolution and reprecipitation under different conditions. These samples were analyzed by WAXS and 13C CP‐MAS NMR spectroscopy. Clear evidence was found that the presence of different crystalline modifications is responsible for the unexpected 13C CP‐MAS NMR spectrum as observed for as‐polymerized PPX. An attempt was made to explain the differences observed in the 13C CP‐MAS NMR spectra of different crystalline modifications by different chemical environments utilizing simulations of the crystal unit cells.

Poly(p-xylylene) and Its Derivatives by Chemical Vapor Deposition: Synthesis, Mechanism, and Structure

“…The signal splitting of the C 2 atom of 3a is due to different crystalline modifications as already pointed out. 15 The 13 C CP-MAS NMR spectrum of 3b prepared from 2d shows signals at 36.5, 130.4, 137.5, and 142.6 ppm (Figure 3), which is in good agreement of previous reports for 3b prepared from chlorinated paracyclophanes. 17 The signal of the aliphatic C atoms is inhomogeneously broadened which is due to the different chemical surrounding of the C 1 and C 2 atoms.…”

Customized Vibrating-Membrane Nozzles for Enhanced Fluid Atomization

“…Afterward, activated samples were wetted with a 3-(Trimethoxysilyl)propyl methacrylate solution (2.0 wt.% in anhydrous toluene, 60 C), followed by rinsing with toluene and vacuum drying. (Gorham 1966;Schmidt et al 1998). The coating process was performed under the following ambient conditions: temperature of the vaporization, pyrolysis and coating chamber at 170, 650, and 20 C, respectively; vacuum degree of »0.1 mbar.…”

A re‐evaluation of fifteen years of european risk assessment using effect models

“…Although α,α′‐dihydroxy‐ p ‐xylylenes,50, 51 α,α′‐ dibromo‐ p ‐xylylenes,52 α‐chloro‐ p ‐xylylenes,53 and α,α′‐diacetoxy‐ p ‐xylylenes54 provide potential candidates for functionalized poly( p ‐xylylene)s as they all have been shown to undergo CVD polymerization, substituted [2.2]paracyclophanes have been the preferred precursors for CVD polymerization—at least in our hands 55. Scheme summarizes the synthesis of [2.2]paracyclophanes with various functional groups.…”