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The development of thermoplastic materials based on starch has become a promising alternative for reducing plastic waste. To this end, plasma treatments were used to enhance the hydrophobicity of cornstarch films. Cornstarch films plasticized using glycerol and distilled water were prepared by casting. A surface modification method was employed using different precursor gases, HMDSO and SF(6), and a combined treatment using HMDSO followed by SF(6) (HMDSO/SF(6)) and then the reverse, using SF(6) first followed by HMDSO (SF(6)/HMDSO). The results indicated that the induced surface morphology determines the contact angle. It was observed that all films became hydrophobic, and films that were initially treated with SF(6) showed the greatest hydrophobicity if no further coating was applied, or if the treated surface was further coated using HMDSO. Under both of these treatment conditions the contact angle was greater than 110°.

This study tested the effectiveness of sulfur hexafluoride (SF6) plasma treatment and acetylene (C2H2) plasma polymerization for turning thermoplastic starch (TPS) hydrophobic. A surface modification method was employed using different precursor gases, SF6 and C2H2, and a combined treatment using SF6 followed by C2H2 (SF6/C2H2) and then the reverse, using C2H2 first followed by SF6 (C2H2/SF6). The same self‐bias voltage and treatment time was used for each gas across all treatments: −100 V and 480 s for SF6, −200 V and 2400 s for C2H2. The best results were obtained from a C2H2‐coated surface, treated with SF6 (C2H2/SF6). This process increased the contact angle to >128°. When treated in the opposite order (SF6/C2H2), the contact angle decreased to 90° and a homogeneous, smoother coating was produced. Raman spectroscopy confirmed the presence of D and G bands in plasma‐treated films. Under these treatments, all surfaces presented a contact angle higher than 75°.

The small-angle X-ray scattering (SAXS) in as-grown and heat-treated quartz crystals was investigated as a function of the azimuth angle around the primary beam. For this, samples parallel to (10 1 10) were extracted from Z-and ÀX-growth sectors of a synthetic quartz bar which had the OH content evaluated by infrared spectroscopy (IRS). In addition, SAXS and IRS were independently recorded as a function of heating temperature. As a result, the two-dimensional SAXS images revealed an anisotropic pattern randomly decorated by lowintensity Kossel lines. The intensities were projected along specific directions or were axially integrated around the primary beam. It was observed that the Porod invariant (Q) increased and the Kossel lines moved slightly to higher q values with increasing temperature. The effect of the sample orientation on the Q value and the lack of a clear relationship between Q and OH content suggested that the diffuse scattering due to the periodicity of the crystal lattice played an important role in the small-angle scattering of quartz. The net scattering intensities produced by heat-treatment at 873 K were attributed to molecular water aggregates created by the diffusion of as-grown OH defects.