Polysiloxanes Modified with Different Types and Contents of Polar Groups: Synthesis, Structure, and Thermal and Dielectric Properties

Abstract

Polymers with high dielectric permittivity are promising for the construction of next-generation transducers and energy storage devices with improved energy density. Here, we report the synthesis, glass-transition temperature (T g ), and dielectric properties of polysiloxanes with different polarities. For this, we set out from poly(dimethyl-co-methylvinyl)siloxanes with different vinyl group content. The vinyl groups were then transformed into polar groups of various nature by an efficient one-step thiol−ene addition postpolymerization modification. We used the resulting collection of materials to establish structure− property relationships, side group design, and thermal and dielectric properties. Our results show that the T g increases with the polar group content and the strength of the polar group. A similar trend is observed for the dielectric permittivity as long as the T g of the polymer is well below 0 °C. Smaller polar groups tend to show a smaller increase in T g , and an increased linker length helps to decreases T g , which is generally favorable for high permittivity. Our findings guided us to design polysiloxanes with a permittivity as high as 27.7 and a T g of −18.2 °C. To the best of our knowledge, this is the highest dielectric permittivity of a polymer with a T g well below room temperature.

Ring-Opening Polymerization (ROP) and Catalytic Rearrangement as a Way to Obtain Siloxane Mono- and Telechelics, as Well as Well-Organized Branching Centers: History and Prospects

“…A large number of studies are also devoted to the preparation of copolymers by the mechanism of catalytic rearrangement. Sheima Y. et al [150] considered the preparation of vinyl functional PDMS by the mechanism of anionic catalytic rearrangement. Then the vinyl groups were converted into polar groups of various nature using an efficient one-step post-polymerization modification of thiol-ene addition (Figure 32).…”

“…One of them is the study by Sheima Y. [150], in which homopolymers of poly(methylvinylsiloxane) (PV) and copolymers of poly(dimethyl-co-methylvinyl)siloxanes (PM x V y ) with ratios x/y = 2:8, 4:6, 6:4, and 8:2 were obtained by ring-opening anionic polymerization of the corresponding D4 and D4 Vi monomers in the presence of hexamethyldisiloxane as the end blocking agent. The vinyl groups were then converted into polar groups of various natures using an efficient one-step post-polymerization modification by the thiol-ene addition mechanism.…”

Electroactive Polymer-Based Composites for Artificial Muscle-like Actuators: A Review

“…The need to use DC voltage higher than 1 kV requires the application of additional specific semiconductor devices, which leads to more complications to activate and control DE actuators. High voltage can harm the human tissues and destroy the device employed, which limits the usage of dielectric materials in medical applications [22][23][24][25][26]. Therefore, to apply them in the medical field requires the reduction of driving voltage.…”

High dielectric permittivity elastomers: synthesis, processability, and device manufacturing

“…Using these strategies, we prepared a library of more than 75 polysiloxanes of different polarities (Scheme 1c), which is ideally suited for elucidating structure/property relationships. [8][9][10] Such exploratory investigations are essential for finding the optimum material for the desired application.…”

“…The thiols that allow introducing polar moieties 1, 2, 3, 5, 11, and 13 are commercial, the last is very expensive and therefore, we synthesized it to reduce costs. 8 The other thiols were synthesized using either our synthetic strategies or reported ones. 12 The polysiloxanes modified with thiols 4 and 10, will be difficult to bring closer to applications because of their demanding synthesis.…”