iCVD Cyclic Polysiloxane and Polysilazane as Nanoscale Thin-Film Electrolyte: Synthesis and Properties

Abstract

A group of crosslinked cyclic siloxane (Si-O) and silazane (Si-N) polymers are synthesized via solvent-free initiated chemical vapor deposition (iCVD). Notably, this is the first report of cyclic polysilazanes synthesized via the gas-phase iCVD method. The deposited nanoscale thin films are thermally stable and chemically inert. By iCVD, they can uniformly and conformally cover nonplanar surfaces having complex geometry. Although polysiloxanes are traditionally utilized as dielectric materials and insulators, our research shows these cyclic organosilicon polymers can conduct lithium ions (Li(+) ) at room temperature. The conformal coating and the room temperature ionic conductivity make these cyclic organosilicon polymers attractive for use as thin-film electrolytes in solid-state batteries. Also, their synthesis process and properties have been systemically studied and discussed.

Vapor deposition routes to conformal polymer thin films

“…For example, tailoring the surface energy of the pore walls of a separation membrane without obstructing the pore can enhance the passage of the desired liquid or gas [2–4]. Conformal coatings can also ensure that micro or nano-device properties (e.g., conductance, capacitance) do not vary due to large thickness variations [5–7]. …”

Cyclic Polysiloxanes with Linked Cyclotetrasiloxane Subunits

“…There are two main methods for the generation of large cyclic polymers,n amely, ring-closing [8] and ring-expansion polymerization. Therefore,the exploration of new reactions for the formation of cyclic polymers is highly desirable to enable the discovery of novel cyclic polymers with new structural features and thus new properties.Theincorporation of constrained cyclotetrasiloxanes into polymers has led to the development of aw ide range of functional materials,i ncluding thin-film electrolytes, [14] selfhealing, [15] thermally stable materials, [16] highly oxygen permeable films, [17] spreading reagents, [18] liquid crystals. [12] Theo verall structural features of the cyclic polymers are determined by the reaction used to construct them, [13] and there the type of reaction used is directly related to the kind of functional groups tolerated.…”

“…[12] Theo verall structural features of the cyclic polymers are determined by the reaction used to construct them, [13] and there the type of reaction used is directly related to the kind of functional groups tolerated. Therefore,the exploration of new reactions for the formation of cyclic polymers is highly desirable to enable the discovery of novel cyclic polymers with new structural features and thus new properties.Theincorporation of constrained cyclotetrasiloxanes into polymers has led to the development of aw ide range of functional materials,i ncluding thin-film electrolytes, [14] selfhealing, [15] thermally stable materials, [16] highly oxygen permeable films, [17] spreading reagents, [18] liquid crystals. [19] However,t he combination of constrained siloxane rings with cyclic polymers has not been investigated owing to the lack of an efficient way of constructing cyclotetrasiloxanering-containing cyclic polymers,a nd therefore the use of cyclic polymers in these areas is limited.…”

“…Theincorporation of constrained cyclotetrasiloxanes into polymers has led to the development of aw ide range of functional materials,i ncluding thin-film electrolytes, [14] selfhealing, [15] thermally stable materials, [16] highly oxygen permeable films, [17] spreading reagents, [18] liquid crystals. [19] However,t he combination of constrained siloxane rings with cyclic polymers has not been investigated owing to the lack of an efficient way of constructing cyclotetrasiloxanering-containing cyclic polymers,a nd therefore the use of cyclic polymers in these areas is limited.…”

Cyclic Polysiloxanes with Linked Cyclotetrasiloxane Subunits

“…The incorporation of constrained cyclotetrasiloxanes into polymers has led to the development of a wide range of functional materials, including thin‐film electrolytes, self‐healing, thermally stable materials, highly oxygen permeable films, spreading reagents, liquid crystals . However, the combination of constrained siloxane rings with cyclic polymers has not been investigated owing to the lack of an efficient way of constructing cyclotetrasiloxane‐ring‐containing cyclic polymers, and therefore the use of cyclic polymers in these areas is limited.…”