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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]