Copolymers having linked internal polyether blocks and internal polyamide blocks have advantageous physical properties and solvent-gelling abilities. The copolymer may be prepared from a reaction mixture that contains 1,4-cyclohexane dicarboxylic acid (CHDA) and poly(alkyleneoxy) diamine (PAODA). Optionally, the reaction mixture contains no monofunctional compound reactive with either amine or carboxylic acid groups, however some of this monofunctional compound may be present. Dimer diamine and/or dimer acid may be present in the reaction mixture. A copolymer may also be prepared from a reaction mixture containing dimer acid and at least two diamine compound(s) including PAODA and short-chain aliphatic diamine having 2-6 carbons (SDA), wherein: a) the reaction mixture comprises x grams of PAODA and y grams of SDA, and x/(x+y) is 0.8-0.98; b) the reaction mixture weighs z grams, and x/z is at least 0.25; and c) the reaction mixture contains either no co-diacid, or comprises a small amount of co-diacid, wherein, if the reaction mixture comprises a small amount of co-diacid, then acid equivalents from co-diacid contribute less than 25% of the total acid equivalents present in the reaction mixture.