Optimization of Cyclopropylamine Plasma Polymerization toward Enhanced Layer Stability in Contact with Water

Abstract

The present investigation of cyclopropylamine (CPA) plasma polymerization in pulsed and continuous wave radio frequency (RF) discharges leads to the proposition of conditions at which amine-rich films exhibit a good stability in contact with water. The analyses reveal complex structure of CPA plasma polymers containing hydrocarbon chains, primary and secondary amines, nitriles and possibly imines. The decomposition of the monomer in plasma is progressing with the composite parameter W/F (RF power over monomer flow rate) but, in pulsed discharges, it is possible to deposit the films with N/C ratio above 0.24 using higher monomer flow rate. At the optimized monomer flow rate the 280 nm thick film exhibits only 20% thickness loss after 48 h immersion in water and still contains about 5 at% of the NH x environment.

Cyclopropylamine plasma polymers for increased cell adhesion and growth

“…The layer prepared at 33 W exhibited compressive stress of 60 ± 30 MPa, while the layer prepared at 250 W exhibited tensile stress of −90 ± 50 MPa. Hence, as showed before, the stresses in the PP‐CPA layers are quite low but vary depending on the energy input.…”

“…Only the layer deposited at the highest average power, 250 W, exhibited a large increase of surface roughness (by a factor of 50) due to de‐wetting of this film (Figure d). Similarly, as reported by Manakhov et al this morphology is supposed to result from a layer buckling caused by de‐wetting of PP‐CPA due to the release of stresses in the layer after the contact with water.…”

“…The stability of PP‐CPA presented above is significantly better than for the films previously deposited at the floating potential because, in this previous case, the thickness loss was always ≥15% for a wide range of W/F and strong changes in the layer morphologies were evidenced by SEM …”

“…Second, ammonia and allylamine are highly toxic flammable compounds and it is, therefore, preferred to avoid them. Recently, it was shown that the plasma polymerization of non‐toxic cyclopropylamine (CPA) led to the deposition of stable amine rich layers exhibiting 9.6 at.% of NH x environment combined with the thickness loss of 2% . These layers have been already used for the immobilization of biomolecules .…”

Deposition of Functional Plasma Polymers Influenced by Reactor Geometry in Capacitively Coupled Discharges

“…Functional plasma polymers, mainly comprising oxygen‐ or nitrogen‐containing groups, are of increasing importance for biomedical applications, but also as adhesion‐promoting layers . Therefore, their stability in ambient air and in aqueous environments is crucial for many applications.…”