Fabrication of Healable Siloxane Oligomers and Their Applications as Functional Coatings


Student thesis: Doctoral Thesis

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Award date2 Oct 2018


Silicones have been widely used in research areas and industrial fields due to their merits of water proof, chemical resistance, and biocompatibility. However, traditional silicone materials crosslinked by irreversible covalent bonds cannot heal themselves after mechanical damage especially those serving in wet or aqueous environments, and the emerging self-healable silicone-based supramolecular materials usually lack stiffness and mechanical strength.

In this research, a new type of self-healable silicones through the hydrogen-bond assisted multiphase assembly of siloxane oligomers were designed and synthesized.Specifically, there are three parts in this thesis.

In the first part, a new class of silicone-based materials (UP)3T built from multiphase-assembled siloxane oligomers through multivalent hydrogen bonding are reported. The developed silicone polymer network is outstanding in regard to its mechanical strength which is competitive to those silicone materials crosslinked by (dynamic) covalent bonds and much higher than those crosslinked by non-covalent bonds. The strong and crystallizable multivalent hydrogen bonds are responsible for the high mechanical strength of the developed silicone material. Furthermore, our materials exhibit a unique feature of water-enhanced healing that environmental water molecules can travel through the gas-permeable siloxane network to aid dissociation of the multivalent hydrogen bonds to achieve rapid healing with high efficiency (underwater: 70°C, 5 min strength recovery of 98% of the pristine value).

In the second part, robust coatings with low oil sliding angles and healable properties can be easily generated through surface coating the siloxane polymers onto various substrates. Compared with other lubricated surfaces, this non-lubricated surface exhibits durable oil-repellency resulting from the siloxane chains connected through hydrogen bonding, and can repel most oils. Moreover, the supramolecular polymers can be coated on various substrates firmly, holding great potential for a broad range of applications in self-cleaning, antifouling, anti-smudging and so on.

In the third part, a long-term durability and reliability photonic material was prepared from supramolecular nanocomposites with good structural colors and fast self-healing properties is presented. The nanocomposite membranes obtained from co-assembly of UPy motif-modified monodispersed silica particles and self-healable UPy motif-terminated polyurea-silicone supramolecular polymers in an atmospheric environment can self-heal in several seconds duplicately after physical damage without any obvious structural color weakening.