Advances and challenges in the field of plasma polymer nanoparticles

Abstract

This contribution reviews plasma polymer nanoparticles produced by gas aggregation cluster sources either via plasma polymerization of volatile monomers or via radio frequency (RF) magnetron sputtering of conventional polymers. The formation of hydrocarbon, fluorocarbon, silicon- and nitrogen-containing plasma polymer nanoparticles as well as core@shell nanoparticles based on plasma polymers is discussed with a focus on the development of novel nanostructured surfaces.

Keywords: gas aggregation cluster source; nanocomposite; nanoparticles; plasma polymer; sputtering.

Figure 1

Scheme of a gas aggregation cluster source.

Figure 2

SEM images of different types of plasma polymer nanoparticles produced: a) by plasma polymerization of n-hexane in its mixture with N₂; b) by plasma polymerization of HMDSO in its mixture with Ar (obtained in a similar manner as [53]); c) by RF magnetron sputtering of nylon in the Ar/N₂ mixture (republished from [54] with permission IOP Publishing Ltd.); d) by RF magnetron sputtering of PTFE in Ar (obtained in a similar manner as [55]). The references shown here and in the following figures cite the authors’ previous works where similar (but not necessarily identical) data were presented; the unreferenced data represent the authors’ new material which has not been published yet, but which is necessary for a comparative analysis in this review.

Figure 3

Experimental arrangements allowing estimation of plasma polymer NP charging: a) electrostatic plates used for deflection of charged nylon-sputtered NPs [66] by applying 200 V voltage of different polarity across the NP beam; b) electrostatic grids used for retardation of charged PTFE-sputtered NPs by applying 1000 V voltage of different polarity along the NP beam (obtained in a similar manner as [55]).

Figure 4

C 1s XPS of the NPs prepared a) by plasma polymerization of n-hexane in its mixture with Ar (total pressure 88 Pa, discharge power 40 W, C₆H₁₄ flow 1.2 sccm, Ar flow 12.2 sccm); b) by RF magnetron sputtering of nylon in the Ar/N₂ 3:1 mixture (obtained in a similar manner as [54]); c) by RF magnetron sputtering of PTFE in Ar (reprinted from [67], with permission from Elsevier).

Figure 5

SEM images of nitrogen-containing NPs prepared a) by plasma polymerization of n-hexane in its mixture with Ar (total pressure 88 Pa, discharge power 40 W, C₆H₁₄ flow 1.2 sccm, Ar flow 12.2 sccm); b) by plasma polymerization of n-hexane in its mixture with N₂ (total pressure 88 Pa, discharge power 40 W, C₆H₁₄ flow 1.2 sccm, N₂ flow 12.2 sccm); c) by RF magnetron sputtering of nylon in the Ar/N₂ 3:1 mixture (obtained in a similar manner as [54]).

Figure 6

Chemical composition of nitrogen-containing NPs shown in Figure 5: a) FTIR spectra; b) the nitrogen content calculated from the XPS spectra as a function of the N₂ concentration in the working gas.

Figure 7

SEM images of NPs prepared by plasma polymerization of HMDSO mixed with Ar: a) without adding oxygen; b) with addition of oxygen at O₂/HMDSO 1:1 ; c) with addition of oxygen at O₂/HMDSO 5:1 (obtained in a similar manner as [53]). Total pressure is 55 Pa, discharge power is 30 W, HMDSO flow is 0.2 sccm, Ar flow is 2 sccm.

Figure 8

Chemical composition of the NPs shown in Figure 7: a) FTIR spectra b) the elemental content calculated from the XPS spectra as a function of the O₂ concentration in the working gas (republished from [53] with permission of IOP Publishing Ltd.).

Figure 9

Mean diameter of nylon-sputtered, PTFE-sputtered and HMDSO plasma polymer NPs as a function of a) the residence time and b) the power of the discharge. The data are calculated from the results presented in [–5467].

Figure 10

SEM images of the PTFE-sputtered NPs deposited with different intensity of the magnetic field: a) 100 G, b) 250 G; Ar pressure is 100 Pa, flow rate is 9.2 sccm, residence time is 9 s, discharge power is 140 W, deposition time is 20 min; obtained in a similar manner as in [55].

Figure 11

SEM images of NPs prepared by plasma polymerization of HMDSO in Ar: a) 220 nm NPs produced with 10 cm aggregation length; b) 40 nm NPs produced with 4 cm aggregation length; c) dual-scale structure produced by sequential deposition of a) and b); d) triple-scale structure produced by power-dependent sequential deposition of 200, 110 band 70 nm diameter NPs; e) size distribution histogram corresponding to d) (republished from [53] with permission of IOP Publishing Ltd.).

Figure 12

Scheme of synthesis of core@shell NPs by GAS: a) core@shell NPs are produced in the GAS by RF magnetron sputtering of Ag target in the gas mixture of Ar and HMDSO; b) metal NPs are produced by DC magnetron sputtering of Ti target in the GAS and then covered by shells of C/H plasma polymer in the auxiliary plasma reactor with external RF excitation.

Figure 13

TEM images of core@shell NPs: a) Ag@HMDSO NPs prepared in configuration of Figure 12a (total pressure 190 Pa, discharge power 50 W, HMDSO flow 0.45 sccm, Ar flow 105 sccm); b) Ti@C/H NPs prepared in configuration of Figure 12b (Ar pressure/flow in the GAS is 40 Pa/4.0 sccm, DC 0.4 A, total pressure in the auxiliary plasma zone is 1 Pa (0.65 Pa of Ar and 0.35 Pa of C₆H₁₄), RF power is 10 W).

Figure 14

C/H NPs prepared in GAS by plasma polymerization of n-hexane and overcoated a) with a thin film of C/H plasma polymer (reprinted from [76], with permission from Elsevier) and b) with a Ti thin film (obtained in a similar manner as in [77]).

Figure 15

Scheme of GLAD: a) preseeding of substrates with nylon-sputtered NPs produced by GAS; b) GLAD of nylon-sputtered plasma polymer over the preseeded NPs.

Figure 16

SEM images with combined top view and cross-sections of the deposits produced as a result of RF magnetron sputtering of nylon: a) normal deposition on blank Si substrate; b) GLAD at 80° on blank Si substrate; c) normal deposition over preseeded nylon-sputtered NPs; d) GLAD at 80° over preseeded nylon-sputtered NPs (reprinted from [81], with permission from Elsevier).