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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Hyperthermal intact molecular ions play key role in retention of ATRP surface initiation capability of plasma polymer films from ethyl alpha-bromoisobutyrate
AU - Saboohi, Solmaz
AU - Coad, Bryan R.
AU - Michelmore, Andrew
AU - Short, Robert D.
AU - Griesser, Hans J.
PY - 2016/6/29
Y1 - 2016/6/29
N2 - We report a systematic study of the plasma polymerization of ethyl alpha-bromoisobutyrate (EBIB) to produce thin film coatings capable of serving as ATRP initiation surfaces, for which they must contain alpha-bromoisobutyryl functional groups. In the deposition of polymeric coatings by plasma polymerization there generally occurs considerable fragmentation of precursor ("monomer") molecules. in the plasma; and the retention of larger structural elements is challenging, particularly when they are inherently chemically labile. Empirical principles such as low plasma power and low pressure are usually utilized. However, we show that the alpha-bromoisobutyryl structural moiety is labile in a plasma gas phase and in low pressure plasma conditions, below the collisional threshold, there is little retention. At higher pressure, in contrast, fragmentation of this structural motif appears to be reduced substantially, and coatings useful for ATRP initiation were obtained. Mass spectrometry analysis of the composition of the plasma phase revealed that the desired structural moiety can be retained through the plasma, if the plasma conditions are steered toward ions of the precursor molecule. 'Whereas at low pressure the plasma polymer assembles mainly from various neutral (radical) fragments, at higher pressure the deposition occurs from hyperthermal ions, among which the protonated intact molecular ion is the most abundant. At higher pressure, a substantial population of ions has low kinetic energy, leading to "soft landing" and thus less fragmentation. This study demonstrates that relatively complex structural motifs in precursor molecules can be retained in plasma polymerization if the chemical and physical processes occurring in the plasma phase are elucidated and controlled such that desirable larger structural elements play a key role in the film deposition.
AB - We report a systematic study of the plasma polymerization of ethyl alpha-bromoisobutyrate (EBIB) to produce thin film coatings capable of serving as ATRP initiation surfaces, for which they must contain alpha-bromoisobutyryl functional groups. In the deposition of polymeric coatings by plasma polymerization there generally occurs considerable fragmentation of precursor ("monomer") molecules. in the plasma; and the retention of larger structural elements is challenging, particularly when they are inherently chemically labile. Empirical principles such as low plasma power and low pressure are usually utilized. However, we show that the alpha-bromoisobutyryl structural moiety is labile in a plasma gas phase and in low pressure plasma conditions, below the collisional threshold, there is little retention. At higher pressure, in contrast, fragmentation of this structural motif appears to be reduced substantially, and coatings useful for ATRP initiation were obtained. Mass spectrometry analysis of the composition of the plasma phase revealed that the desired structural moiety can be retained through the plasma, if the plasma conditions are steered toward ions of the precursor molecule. 'Whereas at low pressure the plasma polymer assembles mainly from various neutral (radical) fragments, at higher pressure the deposition occurs from hyperthermal ions, among which the protonated intact molecular ion is the most abundant. At higher pressure, a substantial population of ions has low kinetic energy, leading to "soft landing" and thus less fragmentation. This study demonstrates that relatively complex structural motifs in precursor molecules can be retained in plasma polymerization if the chemical and physical processes occurring in the plasma phase are elucidated and controlled such that desirable larger structural elements play a key role in the film deposition.
KW - hyperthermal polyatomic ions
KW - molecular ion
KW - plasma polymerization
KW - ATRP
KW - surface grafting
KW - ethyl alpha-bromoisobutyrate
KW - plasma analysis
KW - TRANSFER RADICAL POLYMERIZATION
KW - CHEMICAL-VAPOR-DEPOSITION
KW - ACRYLIC-ACID
KW - ENERGY
KW - CHEMISTRY
KW - BRUSHES
KW - GROWTH
U2 - 10.1021/acsami.6b04477
DO - 10.1021/acsami.6b04477
M3 - Journal article
VL - 8
SP - 16493
EP - 16502
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
SN - 1944-8244
IS - 25
ER -