This invention provides the following: an amphiphilic functional substance with lipophilicity, affinity for supercritical CO.sub.2, and if necessary hydrophilicity comprising an oligoolefin chain and a perfluoroalkyl group(s) at a single end thereof or at both ends thereof with or without the intervention of a poly(oxyalkylene) chain, which enables the utilization of supercritical CO.sub.2 as a reaction medium; a photopolymerizable functional substance comprising an oligoolefin chain and a reversible photopolymerization/dissociation group(s) at a single end thereof or at both ends thereof and a functional substance comprising a photo- and/or thermodissociable polymer obtained by photopolymerization of the aforementioned photopolymerizable functional substance, which can be utilized as recycle polymers; a hydrolyzable functional substance comprising a polymer obtained by chain-elongating plural oligoolefin chains through ester linkages, which can be utilized as a recycle polymer; and a functional substance capable of forming a microphase separation structure comprising a polymaleimide comprising an oligoolefin chain and a polydimethylsiloxane chain which are bonded to form an imide linkage, which can be utilized as a functional product such as an electronic material. There is also provided novel oligo(1-butene) containing a terminal vinylidene group, which is useful as a raw material in producing the group of functional substances described above.