Design,Synthesis And Applications Of Linear Polysiloxane Based Functional Silicone Materials

Polysiloxane materials have been widely used in the fields of electronics and electric,defense industry,construction,chemical industry,transportation,medical and health care,and people's daily life due to their unique characteristics including low surface free energy,optically transparent and thermostability.Polysiloxane polymers have various stereoscopic configurations(linear,dendritic,cyclic and reticulated)and functional groups(mercaptopropyl,aminopropyl and unsaturated double bond),which offer diversified options for the construction of functional silicone materials,thus exhibiting promising application prospect.In addition,the development of polymerization technique further provides powerful support for developing advanced polysiloxane materials.In this paper,linear polysiloxane with different functional groups,such as polymercaptopropylmethyl-siloxane,monomethacryloxypropyl terminated polydimethylsiloxane and polyaminopropylmethanyl-siloxane,have been utilized to design and synthesize a series of functional polysiloxane materials through appropriate polymerization techniques,and their applications were investigated.Superhydrophobic oil-water separation sponge,containing polymercaptopropylmethyl-siloxane modified polydopamine(PDA)coating,was fabricated through a two-step method:dopamine chemistry and Michael addition.The constructed PDA coating could offer both rough micro-nano structure and reactive sites for the superhydrophobic modification.The fabricated sponge materials were systematically characterized and showed application advantages including high porosity,high absorption capacity,good selectivity and extraordinary recyclability.Besides,the reported preparation method does not need harsh reaction conditions and complex equipments,thus exhibiting great promise in the field of oil-water separation.Superhydrophobic oil-water separation sponge material,containing melamine-formaldehyde(MF)sponge substrate,magnetic polydopamine(PDA)coating and branched polydimethylsiloxane(PDMS)brush,was fabricated through the dopamine mediated surface initiated atom transfer radical polymerization(SI-ATRP).The decorated PDMS brushes can effectively overcome the size mismatch between sponge macropores and tiny emulsified droplets,while remaining the intrinsic macroporous characteristic.When treating W/O emulsions,the PDMS brushes stretch up to act as"interface-breaking blades" to accelerate the coalescence of emulsified water droplets Meanwhile,such PDMS brushes can serve as "oil-traping tentacles" to efficiently capture oil droplets when treating O/W emulsions.Besides,the reported sponge also inherits flame resistance,robust durability,superior recyclability and convenient magnetic collectionBy the comprehensive application of molecular structure design and light-induced"grafting-onto" ATRP,a clean and efficient PDMS brush modification technique was developed.Firstly,a bottle-brush polymer containing benzophenone(Bp)terminal and polydimethylsiloxane units(Bp-PDMS)was synthesized.Subsequently,this Bp-PDMS was utilized to anchor PDMS brush via the photo-reactive Bp terminal to fabricate superhydrophobic sponge.UV-induced "grafting onto" ATRP,anchoring end-functional polymer brushes onto the substrate surface through efficient coupling reactions,could avoid the limitation of "grafting from" ATRP on the bulk substrate,and realized the large-scale preparation of PDMS modified superhydrophobic sponge.The prepared superhydrophobic sponge has good fire resistance,excellent oil absorption performance and reusability,and its separation performance for immiscible oil-water mixtures,W/O emulsions and O/W emulsions was explored.A polysiloxane network with remodeling and self-healing properties was obtained through Diels-Alder(D-A)reaction.Firstly,Furan functionalized polyaminopropylmethanyl-siloxane(F-PDMS)was designed and synthesized.Then,a polysiloxane network containing dynamic reversible covalent bonds was prepared via the D-A click reaction between F-PDMS and maleimide functionalized siloxane(MS).The prepared polysiloxane network material has good remodelability,due to the thermally reversible characteristics of the D-A reaction.In addition,a methylfuran functionalized polyaminopropylmethanyl-siloxane(MF-PDMS)was also designed and synthesized.The introduction of a methyl group on the furan moiety could reduce the activation energy in the D-A reaction and generate a faster gelation procese.