The Effect of Phenyl Content on the Liquid Crystal-Based Organosilicone Elastomers with Mechanical Adaptability

Abstract

An elastomer with mechanical adaptability is a new kind of polymer material in which the increasing stress under continuous deformation is significantly inhibited in a large deformation area. Liquid crystal-based organosilicone elastomers, which can dissipate energy through reversible internal phase transition under external stimulation and have recoverable large deformation capacity, have drawn much interest as mechanical adaptability materials. However, there is no good way to control the mechanical adaptability at present. For this purpose, we prepared a new liquid crystal-based phenyl silicone rubber (LCMVPQ) using two-step click reactions and systematically explored the effect of phenyl content on its mechanical adaptability to achieve the regulation of mechanical adaptability. With an increase in phenyl content in the LCMVPQs, phenyl can hinder the rearrangement of the mesogenic units along the applied stress direction, which enables the adjustment of mechanical adaptability to meet the needs of different situations. In addition, the introduction of the liquid crystal phase impedes the internal friction of the molecular chain movement of the LCMVPQs and reduces the damping performance of silicone rubber. This research achieves the regulation of elastomers with mechanical adaptability and is expected to be applied in practical application fields.

Synthesis and Characterization of a Liquid Crystal-Modified Polydimethylsiloxane Rubber with Mechanical Adaptability Based on Chain Extension in the Process of Crosslinking

“…The mechanical strength of MBB-MQ is up to 5.83 MPa and the elongation at break is more than 10 times its own length, which are higher than those in our previous study. 32 , 33 Similarly, the mechanical strength of 3CCV-MQ is also up to 4.71 MPa, and the elongation at break is more than 10 times its own length. The reason is as follows: in order to ensure the complete graft of 3CCV/MBB, thiol groups are excessive in the preparation of 3CCV/MBB-modified polydimethylsiloxane, and in the process of further click reaction, excessive thiol groups react with the terminal vinyl group of 3CCV/MBB-modified polydimethylsiloxane to achieve the effect of chain extension, which significantly improves the mechanical strength and elongation at break of 3CCV/MBB-MQ compared with MQ.…”

“…In our previous work, we developed several kinds of liquid crystal-based organosilicone elastomers with mechanical adaptability, whose mechanical tensile strength was up to 4 Mpa. 32 , 33 However, the production process of introducing the crosslinking system with liquid crystal units as the crosslinking center in our previous study is complicated, and it is very difficult to prepare large size samples for practical applications. 34 − 37 …”

“…24−28 Due to high-and low-temperature resistance, aging resistance, weather resistance, and other excellent characteristics, 29−31 work, we developed several kinds of liquid crystal-based organosilicone elastomers with mechanical adaptability, whose mechanical tensile strength was up to 4 Mpa. 32,33 However, the production process of introducing the crosslinking system with liquid crystal units as the crosslinking center in our previous study is complicated, and it is very difficult to prepare large size samples for practical applications. 34−37 Hence, we developed a liquid crystal-modified polydimethylsiloxane rubber with mechanical adaptability based on chain extension in the process of crosslinking by ingenious structure design.…”

“…Although many research groups have done a lot of work on liquid crystal elastomers, − there is very little published research on its mechanical adaptability, and the mechanical tensile strength in previous literature almost never exceeds 1 MPa. − Due to high- and low-temperature resistance, aging resistance, weather resistance, and other excellent characteristics, − our group has been committed to developing mechanical adaptive materials based on polydimethylsiloxane to ensure the application of this material under harsh environments, and commercially available PDMS-based elastomers do not perform this function. In our previous work, we developed several kinds of liquid crystal-based organosilicone elastomers with mechanical adaptability, whose mechanical tensile strength was up to 4 Mpa. , However, the production process of introducing the crosslinking system with liquid crystal units as the crosslinking center in our previous study is complicated, and it is very difficult to prepare large size samples for practical applications. − …”