NOVELTY - A substance (i.e. modified polymer) comprising a bulk derivative of polyamide 46, is new.    USE - As substance (i.e. modified polymer) comprising a bulk derivative of polyamide 46 in the manufacturing of wound dressing, implant, artificial bone, artificial kidney, anionic or uncharged membrane, synthetic strong sheets, fuel cell, anti-fog packages, breathable packages, textile, ion-exchanger, color fixer in textile industry, matrix for immobilizer of nanoparticles, metal remover polymer, deodorant, antimicrobial agent, softener and conditioner, and air conditioner filters (claimed); and in textile industry, filtering processes, selective sorption, controlled release devices, phase transfer catalysts, chromatographic media, biocompatible capsules, artificial skins and organs, and fuel cells.    ADVANTAGE - The polyamide 46 has good mechanical, physical and chemical properties compared to other aliphatic polyamides. The substance has some improved features, such as e.g. water absorbance. The bulk modification provides recyclable and durable polymer after dissolution in a relevant solvent or reprocessing by melting without changing any properties in order to re-use several times, unlike surface modification where any dissolution or re-melting can destroy the surface of the modified polymer. The shape of the polymer is under control, which means that one can easily give any shape to the polymer by melting, by dissolving in solvent, or by coating other materials such as metals, glass or natural fibers as properties enhancer. The substances are stable and durable in any environments.    DETAILED DESCRIPTION - A substance (i.e. modified polymer) comprising a bulk derivative of polyamide 46, and having formula (-NH-CH2-CH2-CH2-CH2-NR-CO-CH2-CH2-CH2-CH2-CO-)n (I), is new.    R=hydroxyalkyl, acyl or carboxyalkyl;    n=natural number 50-500 (preferably 100-150, especially 115-125).    INDEPENDENT CLAIMS are included for the following:    (1) method for preparing the substance; and    (2) a system for the synthesis of the substance based on the method.