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Keywords:

  • α-dimethyl parylene;
  • Alkoxide;
  • Alternating copolymer;
  • Optical properties;
  • Thermal stability

Abstract

The parylene CVD platform is a unique one since it enables the room temperature deposition of high-performance polymers from the resonance-stabilization of the p-xylylene intermediate. This intermediate, or the derivatives of it, have the same stabilization. Regardless of the precursor, albeit the more common [2.2] paracyclophane or monomer routes, there are two sites to derivatize the parylene precursor, the alpha or benzylic position or the phenyl ring. The work here explores the addition of methyl groups to the alpha position of p-xylylene or parylene. The results show that the resulting polymer, poly(α,α′-dimethyl-p-xylylene) shares many of the properties of parylene E (phenyl-modified ethylated parylene); however, with a higher thermal stability, 400 °C. A homopolymer of poly(α,α,α′,α′-tetramethyl-p-xylylene) is not possible due to steric hinderance of the methyl groups, but an alternating copolymer, poly(α,α,α′,α′-tetramethyl-p-xylylene)-co-poly(p-xylylene), is deposited.