Formation of lateral chemical gradients in plasma polymer films shielded by an inclined mask

Abstract

Low pressure plasma deposition conditions are investigated yielding oxygencontaining lateral gradient coatings (a─C:H:O) by means of an inclined static mask partly shielding the substrate. Such lateral gradient coatings are formed by the diffusion of film-forming species with different reactivities underneath the mask.Surface characterization revealed varying film growth conditions below the mask different from direct plasma exposure with increasing distance from the mask/plasma edge: i) exponentially decreasing film growth; ii) decreasing roughness following the thickness trend; iii) decreasing hydrophilicity; iv) variation in cross-linking; and v) different chemical composition.Oxygen-rich film-forming species appeared to react closer to the mask/plasma edge, while oxygen-poor film-forming species can diffuse deeper, leading to a pronounced gradient in chemical composition and in cross-linking in the masked area. K E Y W O R D Sdiffusion, film-forming species, lateral gradient structure, plasma polymerization, static mask Plasma Process Polym. 2018;15:e1700185.www.plasma-polymers.com

Insight into peculiar adhesion of cells to plasma‐chemically prepared multifunctional “amino‐glue” surfaces

“…The PP type selection was based on previous detailed studies of PECVD from cyclopropylamine (CPA) vapors mixed with Ar (for amine PPs), [13,22,23] and PECVD from the mixture of ethylene (C 2 H 4 ) and carbon dioxide (CO 2 ) for carboxyl PPs. [24][25][26] Three types of amine PPs were deposited at a pressure of 50 Pa and an Ar flow rate of 28 sccm; the flow rate of CPA was held at 2 sccm. In two cases, the radio frequency (RF) discharge was operated in the pulsed mode using the duty cycle (DC) of 33% and the repetition frequency of 500 Hz.…”

“…The carboxyl PPs were deposited according to the procedure previously optimized on Si substrates for improved stability and surface functionality. [24,25] The C 2 H 4 gas flow rate was held constant at 4 sccm. First, a highly crosslinked base layer was prepared at the RF power and the CO 2 /C 2 H 4 flow rate ratio of 70 W and 2:1, respectively.…”

Plasma polymer film designs through the eyes of ToF-SIMS

“…1(a)]. 33 Amino-based (named "CN-"), respectively, CO-bilayers were deposited in a one-step process by a fast change of the plasma conditions at a predefined point in time during the deposition to obtain a highly cross-linked polymer base layer, covered by a less cross-linked but more functional top layer. 19,21 On the one hand, the power was decreased to reduce the ionic bombardment and thus the cross-linking of the top layer polymer.…”

“…11 In addition, a slight increase in C/H is observed in the direction toward the closed-end. This can be attributed to the decreasing film thickness in this region: 33 Below a thickness of %5 nm, ToF-SIMS detects the polymer fragments which are directly attached to the substrate. This is supported by the detection of increasing SiCintensity in this region (not shown here).…”

Preparation of Compositional Gradient Polymeric Films Based on Gradient Mesh Template

“…Due to the concentration gradient of the polymers, many important properties of the films such as wettability, mechanical/optical/thermal properties, density of functional groups and cell adhesion as a function of the elastic modulus can be finely tuned. The gradient films can be prepared by many methods, which include dissolution and diffusion methods [11], temperature gradient field method [12], as interpenetrating polymer networks [13], by extrusion [14,15], microfluidic techniques [16,17], electrochemical technique [18], centrifugation [19], and so on [20,21,22]. Till date, FGMs have been potentially used in various fields such as medicine [23,24,25,26,27,28], biology [29,30,31,32], and optics [5,33,34,35].…”