Multifunctional Vitrimer-Like Polydimethylsiloxane (PDMS): Recyclable, Self-Healable, and Water-Driven Malleable Covalent Networks Based on Dynamic Imine Bond

Abstract

Vitrimer is a new class of polymeric materials which can be reprocessed to any shape while being permanently cross-linked. We designed and synthesized a catalyst-free network with poly-(dimethylsiloxane)etherimide (PDMS-NH 2 ), terephthalaldehyde (TA), and tri(2-aminoethyl)amine (TREA) through the condensation reaction between amino groups and aldehyde groups. As a result of the exchange reaction of the dynamic imine bond obtained, this PDMS network exhibits the nature of vitrimer-like material, which is examined by solubility and stress-relaxation experiments, and the relaxation time is as short as 64 s at 130 °C. In addition, the vitrimer-like PDMS is malleable and capable of self-healing, and the mechanical properties can be maintained even after three consecutive breaking/mold pressing cycles. Especially, besides heating, this vitrimer-like PDMS can also be recycled and reshaped at ambient temperature due to the exchange reaction of dynamic imine bond when immersed in water, which will potentially lead to green processing of the elastomers.

Stretchable Electronics Based on PDMS Substrates

“…Additionally, S‐PDMS‐based substrates established according to reversible covalent and noncovalent bonds are difficult to be remolded under mild conditions, whereas polymers based on noncovalent interactions are usually not sufficiently stable under the conditions of heating or solvents; therefore, S‐PDMS vitrimers have been designed and prepared in recent years. In the context of vitrimeric S‐PDMS elastomers, four dynamic associative chemistries have already been explored: dynamic imine bond, [ 165 ] zinc(II)‐catalyzed transesterification, [ 166 ] the addition–elimination of thiols with Meldrum's acid, [ 167 ] and the transamination of vinylogous urethanes. [ 168 ] However, for stretchable S‐PDMS‐based electronics, it is difficult to remold electronic devices.…”

Influence of the polymer matrix on the viscoelastic behaviour of vitrimers

“…As mentioned before, it is so far common practice in vitrimer studies to compare activation energies from model studies or other materials with the same exchange chemistry, without explicitly taking possible matrix effects into account. 5,33,35,37,[39][40][41] However, it can be expected that such effects are real and possibly significant, leading us to conduct this systematic investigation.…”

Development of a Strong, Recyclable Poly(dimethylsiloxane) Elastomer with Autonomic Self‐Healing Capabilities and Fluorescence Response Properties at Room Temperature

“…[9][10][11] In general, self-healing polymers can be fabricated using two fundamental approaches, either the extrinsic method, which involves microencapsulation, [12][13][14] or the intrinsic method, which applies various dynamic chemistries. The intrinsic strategy is also suitable for the fabrication of recyclable polymers because these types of materials possess similar design principles based on reversible covalent bonds (e.g., the Diels-Alder reaction, [15][16][17][18] reversible disulfide bonding, [19][20][21] imine bonds, [22][23][24] dynamic hydrazone bonds, [25] dynamic boronic ester bonds, [26][27][28] transesterification reactions, [29][30][31] or olefin metathesis [32,33] ) and reversible noncovalent bonds (e.g., hydrogen-bonding interactions, [34][35][36][37] host-guest interactions, [38,39] and metalligand interactions [40][41][42] ). It is well known that the reversible formation and cleavage of dynamic bonds and the mobility of polymer chains govern the healing capacity and mechanical properties of intrinsic self-healing polymer composites.…”