A novel polymer having high glass transition temperature and an excellent balance between heat resistance, high refractive index and mechanical properties, and a composition and molded article containing the polymer are provided. The polymer according to the invention has a first structural unit represented by at least one of formulae (1-1), (1-2) and (1-3) below and a second structural unit having either a secondary amino structure or a tertiary amino structure at two or more terminals. ##STR00001##

A novel polymer having high glass transition temperature and an excellent balance between heat resistance, high refractive index and mechanical properties, and a composition and molded article containing the polymer are provided. The polymer according to the invention has a first structural unit represented by at least one of formulae (1-1), (1-2) and (1-3) below and a second structural unit having either a secondary amino structure or a tertiary amino structure at two or more terminals.

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A polymer composition [composition (C)] comprising: (a) a polyarylene ether ketone (PAEK-1) comprising recurring units deriving from the incorporation of 1,4:3,6-dianhydrohexitols; (b) a poly(biphenyl ether) sulfone (PPSU-1) comprising repeating units of formula (I) and/or (c) a polyetherimide (PEI-1) comprising repeating units of formula (II) wherein Ar* and Ar* are as en.) defined in the specification are herein disclosed. (PAEK-1) and (PPSU-1) and/or (PEI-1) are completely miscible and give rise to compositions that are transparent and possess high strength and stiffness and that are suitable for the manufacture of a variety of shaped articles.

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The invention relates to a process for producing semi-aromatic polyethers based on an aliphatic diol, to semi-aromatic polyethers based on an aliphatic diol obtained by said process, and to the use of said semi-aromatic polyethers based on an aliphatic diol for manufacturing membranes, manufactured parts and coatings.

To provide: a block copolymer that exhibits excellent proton conductivity even under low-humidification conditions, exhibits excellent mechanical strength and chemical stability, and when used in a polymer electrolyte fuel cell, allows high output and excellent physical durability; a polymer electrolyte material; and a polymer electrolyte form article and a polymer electrolyte fuel cell, using the same. The block copolymer of the present invention includes each one or more of: a segment (A1) containing an ionic group; a segment (A2) not containing an ionic group; and a linker moiety connecting the segments. The segment (A1) containing an ionic group comprises a constituent unit represented by a specific structure. The polymer electrolyte material, the polymer electrolyte form article, and the polymer electrolyte fuel cell according to the present invention are manufactured by using the above block copolymer.

Polyether ketone compounds obtained by reacting a compound represented by formula (1):

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wherein R.sup.1, X.sup.D, Y.sup.Dc, and n.sup.Dc are defined herein, with a compound represented by formula (2):

##STR00002##

wherein X.sup.e, Y.sup.e, Z.sup.e, and n.sup.e are defined herein, exhibit high thermal resistance.

A polymer electrolyte composition is excellent in practicality which has such an excellent chemical stability as to be able to withstand a strong oxidizing atmosphere during operation of a fuel cell and is capable of achieving excellent proton conductivity under a low-humidified condition and excellent mechanical strength and physical durability as well as a polymer electrolyte membrane, a membrane electrode assembly, and a polymer electrolyte fuel cell which use the polymer electrolyte composition. The polymer electrolyte membrane is a polymer electrolyte membrane that contains at least an ionic group-containing polymer electrolyte and a polyazole, which is a polymer electrolyte membrane in which a phase separation of 2 nm or larger in which the polyazole is a main component is not observed in transmission type electron microscopic observation.