Preparation and characterization of dual-responsive spiropyran-based random copolymer brushes via surface-initiated atom transfer radical polymerization

Figures & data

Figure 1. TEM images of monodispersed silica nanoparticles (bare silica nanoparticles).

Figure 2. TEM images of hybrid nanoparticles SiO₂-g-P(SPMA-co-MAA).

Figure 3. EDS spectrograms of (a) bare silica nanoparticles and (b) hybrid silica nanoparticles coated with P(SPMA-co-MAA).

Figure 4. FT-IR spectra of (a) bare silica nanoparticles and (b) hybrid silica nanoparticles coated with P(SPMA-co-MAA).

Figure 5. XPS spectra of (a) SiO₂, (b) SiO₂–Br, and (c) SiO₂-g-P(SPMA-co-MAA).

Table 1. Surface elements composition of SiO₂, SiO₂–Br, and SiO₂-P(SPMA-co-MAA).

Samples	Si (%)	C (%)	O (%)	Br (%)	N (%)
SiO2	30.2	6.61	62.94	0	0.25
SiO2–Br	27.7	14.76	53.41	1.68	2.46
SiO2-P(SPMA-co-MAA)	23	30.98	42.48	0.63	2.91

Figure 6. High-resolution XPS spectra and curve fitting of O1s of (a) SiO₂ and (b) SiO₂-P(SPMA-co-MAA).

Table 2. O1s high-resolution XPS analysis of SiO₂ and SiO₂-P(SPMA-co-MAA).

Samples	Position (eV)	Content (%)	Attribution
SiO2	532.82	61.60	Si–O
	533.11	38.40	C–O
SiO2-P(SPMA-co-MAA)	531.44	8.40	C=O
	532.65	50.80	Si–O
	533.09	40.80	C–O

Figure 7. The thermogravimetric analysis of (a) SiO₂, (b) SiO₂–NH₂, (c) SiO₂–Br, and (d) SiO₂-P(SPMA-co-MAA).

Figure 8. UV–vis spectra of SiO₂-g-P(SPMA-co-MAA) in THF under different light conditions.

Figure 9. The hydrodynamic diameters distributions of SiO₂-g-P(SPMA-co-MAA) under different light conditions.

Figure 10. The hydrodynamic diameters distributions of SiO₂-g-P(SPMA-co-MAA) in aqueous solutions with different pH values.

Scheme 1. The photochromism scheme of spiropyrans under UV and vis light.

Scheme 2. Synthetic procedure for SiO₂-g-P(SPMA-co-MAA).

Scheme 3. Synthesis route of SiO₂-g-P(SPMA-co-MAA) by SI-ATRP and chemical hydrolysis.

Scheme 4. Schematic illustration of the reversible pH-tunable swelling/shrinking transition.