TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The Lewis acid is AlCl3.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The carbonyl compound (III) is an acid anhydride. The acid anhydride is maleic anhydride or succinic anhydride.    TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): The method for preparing the substance involves: a) reacting the polyamide 46 with an aldehyde of formula R1COH (II), or a carbonyl compound of formula R2COY' (III) or a carboxylic acid of formula XCH(R3)COOH (IV); and b) quenching the reaction mixture with a hydrogen solvent.R1=H or alkyl (preferably H, methyl or ethyl);R2=alkyl or alkenyl;Y'=OR4, OCOR5, NR6R7, or halo;R3=H or alkyl (preferably H or methyl);X=halo (preferably Cl);R4, R5, R6 and R7=alkyl, alkenyl, alkynyl aryl, or arylalkyl.The reaction (a) takes place in the presence of a Lewis acid. The reaction (a) with the aldehyde (II) takes place in the presence of a Lewis acid. Preferred Definitions:    R=hydroxyalkyl in which alkyl is methyl, ethyl or propyl, maleate or succinate, or carboxyalkyl in which alkyl is methyl or ethyl.    EXAMPLE - Stanyl TW300 (RTM: polyamide 46 having Mn of 24000 g/mol) (15 g) was dried in an oven for 1 hour at 55 plus minus 2 degrees C. The dried polyamide 46 was dispersed into 100 ml formic acid (greater than 98%) (1.22 g/ml at 25 degrees C) by gently mixing and heating at 50 plus minus 2 degrees C. This process was followed by adding 20 ml dimethyl sulfoxide (DMSO) (greater than 99.5%) (1.10 g/ml at 25 degrees C) to this mixture. The temperature was increased and kept at 70 plus minus 2 degrees C for 15 minutes to obtain transparent orange-red solution. After complete reaction the temperature was reduced to room temperature. Then, 7.7 g succinic anhydride (greater than 99%) was added to this solution and the temperature was fixed at 65 plus minus 2 degrees C for 40 minutes until all reagents reacted to each other and transparent light orange liquid was obtained. After decreasing the temperature to 25 plus minus 2 degrees C, to this clear solution was then added 300 ml methanol (greater than 99%) and mixed for 5 minutes. The suspended white precipitate modified polyamide was taken off by centrifugation at 9000x g for 10 minutes. This stage was repeated 2 times. The modified polymer was then removed off and dried at 50 degrees C for 6 hours.