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Supramolecular silicone elastomer is a promising material for sustainable development. Here, quadruple hydrogen bonded ureidopyrimidinone (UPy) units were grafted onto high molecular weight polydimethylsiloxanes (PDMS), providing a novel supramolecular silicone elastomer. The high molecular weight PDMS precursor was prepared through a cyclic trimeric phosphazene base catalyzed ring‐opening polymerization of Octamethylcyclotetrasiloxane (D4) and tetravinyltetramethylcyclotetrasiloxane (V4) with a well‐controlled vinyl content. Its side chains were modified by hydroxyl groups via a thiol‐ene reaction. Then UPy units were further grafted on the side chain of high molecular weight PDMS by the isocyanate‐hydroxy reaction. The mechanical and self‐healing properties of the elastomer can be controlled by adjusting the molecular weight of PDMS and the amount of UPy units. The obtained PDMS elastomers displayed excellent stretchability (elongation at break of 1513%), good self‐healing efficiency (76% at 60°C for 2 h), and high resilience (elastic recovery of 93% under 300% strain cyclic stretching). [ABSTRACT FROM AUTHOR]

Quadruple-chain ladder polyphenylsiloxane (Ph-QCLP) was synthesized by a supramolecular template-directed stepwisecoupling and polymerization method including three steps: (1) Multifunctionalladder monomer M2with four Si–Cl,four Si–OMe, and four Si–N groups was designed and synthesizedby precoupling reaction. In solution M2s spontaneously self-assembled to be ladder superstructure(LS) by synergy of the hydrogen bonding and the π–πstacking interactions. Directed by LStemplate in a neutralcondition that guaranteed the Si–OMe and Si–N groupswere left undestroyed, M2s underwentcontrolled hydrolysis of Si–Cl groups and dehydrochlorinationpolymerization to be 1,3-di(3-aminophenylamino)-tetramethoxyl-disiloxane-bridgedladder polyphenylsiloxanes (DCLP). (2) A precursor, bis-m-phenylenediamine-bridged quadruple-chain ladder polyphenylsiloxanes(QCLP), was synthesized via the controlled hydrolysisof Si–OMe groups of DCLPfollowed by confineddehydration polymerization in an alkaline condition which guaranteedthe Si–N groups were still undestroyed. (3) The target Ph-QCLPwas obtained through synchronous bridge-cleavage andin situ condensation of QCLP. The whole reaction processwas well monitored by a concerted combination of FTIR, 1H NMR, X-ray diffraction (XRD), and 29Si NMR measurements.In particular, 29Si NMR, thermogravimetric analysis (TGA),and differential scanning calorimetry (DSC) results confirmed that Ph-QCLPpossessed well-defined quadruple-chain ladder structureand extremely high thermo-stability. [ABSTRACT FROM AUTHOR]

The properties and applications of silicone elastomers depended on the molecular structure and composition of polysiloxane precursors, which were the most technologically important silicon-based polymers. Preparation of perfect diphenyl silicone elastomers was challenging due to the unexpected branches formed during the ring-opening copolymerization (ROCP) of phenylcyclosiloxane monomer. In this contribution, diphenyl silicone elastomer precursors with controlled structure were successfully prepared by cyclic trimeric phosphazene base (CTPB) catalyzed ROCP of octamethylcyclotetrasiloxane (D 4), octaphenylcyclotetrasiloxane (D 4 8Ph), and 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (D 4 Vi) with high molecular weight up to 551.0 kg/mol and dispersity (Đ) ≤ 2.50. 29Si NMR characterization verified the random microstructures of the resulting diphenyl containing polysiloxanes without chain branching. Moreover, the silica-filled elastomer prepared from poly(dimethylsiloxane- co -vinylmethylsiloxane) (PMVS) and poly(dimethylsiloxane- co -diphenylsiloxane- co -vinylmethylsiloxane) (PMPVS) precursors exhibited very high elasticity, which can be stretched to 1043% with a high tensile strength of 7.7 MPa. Thermal oxidation aging test proved the excellent thermal aging resistance of the phenyl-containing silicone elastomers. This work demonstrated facile method to prepare high quality diphenyl containing polysiloxane precursor toward robust silicone elastomers. [Display omitted] • Diphenyl silicone elastomer precursors with controlled structure were successfully prepared by CTPB catalyzed ROCP. • Silica-filled elastomer prepared from PMVS and PMPVS precursors exhibited very high elasticity. • Thermal oxidation aging test proved the excellent thermal aging resistance of the phenyl-containing silicone elastomers. [ABSTRACT FROM AUTHOR]