Heat‐triggered poly(siloxane‐urethane)s based on disulfide bonds for self‐healing application

Abstract

Polydimethylsiloxane (PDMS) is one of the most widely employed silicon‐based polymers for its high flexibility, low usage temperature, excellent water resistance, outstanding electrical insulting property, and physiological inert, etc. However, the covalent‐bonded SiO bonds are unable to heal automatically when damaged, which would result in the failure of the materials and devices. Disulfide bond based polymers show high healing efficiency at moderate temperature and have been investigated intensively. Herein, we report a PDMS‐based polyurethane self‐healing polymer (PDMS‐PU) modified with disulfide bonds, which exhibited a reinforced thermal stability, excellent stretchability, and satisfactory self‐healing ability. The effect of different ratio of PDMS and disulfide bond contents on the elastomer properties was investigated. With the increase of PDMS content, the decomposition temperature of the PDMS‐PU‐3 (332 °C) elastomer with highest content of PDMS was increased by 34 °C compared to PDMS‐PU‐1 (298 °C) with lowest content of PDMS and exhibited a largest elongation at break of 1204%. PDMS‐PU‐1 with highest content of disulfide bond possessed a highest healing efficiency of 97%. The results indicated the PDMS‐PU elastomers can be used as self‐healing flexible substrate for flexible electronics. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46532.

Evaluation of in vitro cytotoxicity and properties of polydimethylsiloxane‐based polyurethane/crystalline nanocellulose bionanocomposites

“…38 Positions of different peaks for neat PU and PU/CNC nanocomposites were similar. 40 Sharp peaks at around 2930 and 2850 cm −1 were related to asymmetric and symmetric stretching vibrations of alkyl groups. 34 This showed that the reaction medium was completely free of moisture and all isocyanate groups have formed urethane groups.…”

“…In HS0.0, endothermic peak at 174.7 C was related to T m,HS . 40 On the other hand, the first stage was related to destruction of HS which had lower thermal stability than SS due to lower molecular weight. The existence of the HS crystals in the polymer demonstrated high phase separation between the HS and SS.…”

“…39 The peak at 2960 cm −1 represented the symmetric stretching vibration of C-H in methyl groups of PDMS. 40 Sharp peaks at around 2930 and 2850 cm −1 were related to asymmetric and symmetric stretching vibrations of alkyl groups. 41 The absorption peak at about 1688 cm −1 in HS0.0 and nanocomposites was attributed to involved-in-hydrogenbonding C O groups.…”

“…First and second steps at 350-500 C with T d,max = 380 C and 472 C were due to the decomposition of urethane bands in HS and third step at 500-600 C was related to PDMS SS areas. 40 On the other hand, the first stage was related to destruction of HS which had lower thermal stability than SS due to lower molecular weight. 50,54 The bond strength of Si O bond is higher than C C bond 40 ; therefore, degradation temperature of PDMS is significantly higher than of polymer containing C C bond.…”

Functionalized graphene‐reinforced polysiloxane nanocomposite with improved mechanical performance and efficient healing properties

“…Extrinsic self‐healing materials require healing agents during the healing process . Although intrinsic self‐healing materials can undergo self‐healing process multiple times through dynamic noncovalent interactions (such as hydrogen bonds and π–π stacking) and dynamic covalent bonds(such as dynamic boroxine bonds, DA bonds and urea bonds). Self‐healing materials based on dynamic covalent bonding have advantages such as high strength, increased thermal stability, and solvent resistance compared to self‐healing materials based on noncovalent interactions.…”