Characterization of the coatings
The molecular weight of HO-PDMS-OH was characterized by matrix-assisted
laser desorption ionization time-of-flight mass spectrometry
(MALDI-TOF-MS, AB SCIEX, MALDI-TOF 5800). Fourier-transform infrared
(FTIR, Bruker Optics, Spectrum 100) spectra were recorded with a
Tensor-27 spectrometer in order to monitor the synergetic reactions, and
KBr was used as the sample matrix. X-ray photoelectron spectroscopy
(XPS, Thermo Fisher Scientific, K-Alpha) was employed to analyze the
elemental compositions of the coating. The morphology and the
energy-dispersive X-ray spectroscopy (EDX) mapping of the coating were
characterized with a scanning electron microscope (SEM, Zeiss,
Sigma300). The morphology and roughness of the coating were investigated
via atomic force microscopy (AFM, Bruker, Multimode 8). Meanwhile,
differential scanning calorimetry (DSC, PerkinElmer, DSC8000)
measurements were performed under a nitrogen atmosphere at heating and
cooling rates of 10 K/min. The optical transmittance of the coating was
measured using a UV-visible spectrometer (Perkin Elmer, Lambda 950) with
air employed as a reference. Pencil hardness tests were performed using
a VF2378 pencil hardness tester (Thermimport Quality Control,
Netherlands).
An abrasion test system (Chuangheng, A20-339) with a piece of cotton
fabric as the abrasion material was used for the abrasion tests, and a
weight of 500 g was placed above the fabric to enhance the abrasion
force.
The contact angles (CAs), sliding angles (SAs), and hysteresis angles
(∆θ = θ A - θ R) were
measured using a contact angle measuring instrument (Shengding,
JC2000A). The droplet volume employed for the CA measurements was 2 μL,
and that used for the SA measurements was 20 μL. Theθ A and θ R were measured by
injecting the test liquids into or withdrawing from the droplets resting
on the coatings until they advanced or receded. The shear strength and
tensile strength were evaluated using a universal tester at a rate of
300 mm/min (Dongguan Lixian, HZ-1007E).
The size of the 3M® Scotch adhesive tape employed for
the shear strength test was 4 cm × 2 cm, while the size of the
3M® Scotch double-sided mounting tape used for the
tensile strength test was 2 cm × 2
cm. A roller with a weight of 2 kg was passed over these tape samples
twice to ensure that they were in full contact with the coatings and
various uncoated substrates, and the strengths were measured 20 min
after this treatment.