Amorphous Highly Conjugated Chemical-Vapor-Deposited Polymer Thin Films

Abstract

Using the parylene polymer platform, benzylic brominated poly(trifluoroacetyl-p-xylylene) thin films are deposited at room temperature from a novel synthesized precursor, 2-trifluoroacetyl-a,a,a′ tribromo-p-xylene using CVD. The as-deposited benzylic brominated parylene-type polymer is nearly transparent. However, upon subsequent post-deposition anneals dehydrohalogenation can take place, yielding vinyl and ethynyl moieties and a highly conjugated absorbing polymer. Previous attempts with the deposition and annealing of the analogous non-functionalized phenyl group polymer did not yield the desired structure, due to polymer crystallization that 'locked up' the structure preventing any further chemical reactions from occurring. The as-deposited films contain much hydroxyl bonding; however, after post-deposition annealing, the films dehydrate and hydrogen bromide eliminates at 200, 300, and 380°C. During HBr removal the films become much thinner, more absorbing in the visible region, and denser. After the 300°C anneal the films stay amorphous, as seen from X-ray diffraction (XRD) measurements, and some bromine still resides in the structure. 0.4 bromine atoms per repeat unit are left compared with 1.8 bromine atoms per repeat unit in the as-deposited condition.

Functionalization of Poly(para‐xylylene)s—Opportunities and Challenges as Coating Material

“…The usage of a trifluoroacetyl group at the phenyl group inhibited the crystallization and made the PPE synthesis possible. [ 80 ]…”

Partially Fluorinated Poly‐p‐xylylenes Synthesized by CVD Polymerization

“…In fact, CVD polymerized, brominated-PPX coatings are known to undergo dehydrohalogenation resulting in vinyl and ethynyl moieties. [17] [3,[18][19][20][21] To further investigate this effect, we have now synthesized and CVD-polymerized a [2.2]paracyclophane with a long perfluorinated side chain. Specifically, compound 3 was synthesized and used to prepare ultrahydrophobic coatings of polymer 4 which contained a carbonyl-functionalized derivative with an 8-carbon perfluorinated side chain (Scheme 1).…”

Morphology-Dependent Optoelectronic Properties of Blue Emitter Poly(p-phenylene) Synthesized with Chemical Vapor Deposition Polymerization

“…In recent years, various CVDP processes have been developed to synthesize successfully poly(p-phenylene vinylene) (PPV) and derivatives in the form of thin film or nanostructure, exhibiting excellent optoelectronic properties. [8][9][10][11][12] In most CVDP processes, a dehydrohalogenation step at hightemperature pyrolysis is required to form the activated intermediate. After the condensation polymerization in a lowtemperature environment, a subsequent thermal conversion treatment under inert gas is necessary to form the wellconjugated structure.…”

“…In this study, PPP thin film synthesis with a dry, facile one-step chemical vapor deposition polymerization (CVDP) process based on a precursor monomer, bis-chloro-biphenylene, is reported. In recent years, various CVDP processes have been developed to synthesize successfully poly( p -phenylene vinylene) (PPV) and derivatives in the form of thin film or nanostructure, exhibiting excellent optoelectronic properties. − …”