NOVELTY - A peptoid oligomer (I) is new.    USE - For producing two-dimensional structures, preferably two-dimensional sheets (claimed) by self-assembling, the two-dimensional nanostructures are useful for fabricating devices, e.g. bioanalytical devices, electrochemical devices, batteries, fuel cells, membranes for filtrations, surface coatings, and biosensors.    ADVANTAGE - The wide variety of functional groups can be incorporated into peptoids, thereby allowing the sheets produced from them to be functionalized with variety of moieties.    DETAILED DESCRIPTION - A peptoid oligomer of formula ((R1)(R3)N-CH2-C(O)-N(R2)-CH2-C(O))n-NH2 (I), is new.    R1 and R2=hydrophilic or polar side-chain, or hydrophobic or apolar side-chain (preferably R'a, OR'a, NR4R'b, S(O)1-4R'a, C(O)R'a, C(O)OR'a, OC(O)R'a, OC(O)OR'a, NR'bC(O)R'a, C(O)NR'aR'b, -OC(O)NR'aR'b, NR'cC(O)NR'aR'b, NR'bC(O)OR'a, R'a-O-R'b, R'a-NR'bR'c, SO3, SO4, -SO2NH-R'a, -R'a-S-R'b, -R'a-S(O)-R'b, -R'a-S(O)2-R'b, -OR'a-O-R'b, -NR'aR'b-O-R'c, -SO1-4R'a-O-R'b, -C(O)R'a-O-R'b, -C(O)OR'a-O-R'b, OC(O)R'a-O-R'b, OC(O)OR'a-O-R'b, -NR'bC(O)R'a, -O-R'c, -C(O)NR'aR'b-O-R'c, -OC(O)NR'aR'b-O-R'c, -NR'cC(O)NR'aR'b-O-R'd, -NR'bC(O)OR'a-O-R'c, -OR'a-S-R'b, -NR'aR'b-S-R'c, -SO1-4R'a-S-R'b, -C(O)R'a-S-R'b, -C(O)OR'a-S-R'b, -OC(O)R'a-S-R'b, -OC(O)OR'a-S-R'b, -NR'bC(O)R'a-S-R'c, -C(O)NR'aR'b-S-R'c, -OC(O)NR'aR'b-S-R'c, -NR'cC(O)NR'aR'b-S-R'd, -NR'bC(O)OR'a-S-R'c, -OR'a-NR'bR'd, -NR'aR'b-NR'cR'd, -S(O)1-4R'a-NR'bR'd, C(O)R'a-NR'bR'd, -C(O)OR'a-NR'bR'd, -OC(O)R'a-NR'bR'd, -OC(O)OR'a-NR'bR'd, -NR'bC(O)R'a-NR'cR'd, -C(O)NR'aR'b-NR'cR'd, -OC(O)NR'aR'b-NR'cR'd, -NR'cC(O)NR'aR'b-NHR'd, -NR'bC(O)OR'a-NR'cR'd, PO3, PO4, -PO2-R'a, -R'a-PO3, -R'a-PO4, or -R'a-PO2-R'b, especially apolar side-chain -CH2CH2-C6H5, or the polar side-chain -CH2CH2COOH, or -CH2CH2-NH2);    R'a-R'd=H, alkyl, alkenyl, alkynyl, aryl, aralkyl, aralkenyl or aralkynyl (all substituted by 0-6 halo, NO2, OH, lower alkyl, SH, SO3, NH2, C(O)OH, lower acyl, lower acyloxy, lower alkylamino, lower dialkylamino, trihalomethyl, CN, lower alkylthio, lower alkylsufinyl, or lower alkylsulfonyl);    R3=H or capping group (preferably R'a);    n= greater than or equal to 2.    The structure within the brackets in the formula (I) is a monomer subunit and each monomer subunit can be identical or distinct from each other. Provided that:    (1) when R1 is hydrophilic or polar side-chain, then R2 is a hydrophobic or apolar side-chain;    (2) when R2 is a hydrophilic or polar side-chain then R1 is a hydrophobic or apolar side-chain;    (3) the number of carbon atoms in the longest carbon chain of R'a-R'd is 1 less than or equal to 8; and    (4) when the side-chain is R'a, then R'a comprises at least two carbon atoms.    INDEPENDENT CLAIMS are included for the following:    (1) a population (P1) of the peptoid oligomers (I), where each peptoid oligomer within the population comprises: (a) identical or different numbers of monomer subunits, (b) monomer subunits of identical or different side-chains, or (c) identical or different R3; and    (2) a two-dimensional sheet comprising the population (P1) of the peptoid oligomer (I) assembled into a two-dimensional sheet structure.