TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The composition comprises 5-80 vol.% (preferably 10-60 vol.%) thermally conductive filler, with regards to the volume of polymer network. The polymer network comprises hydrocarbon chains comprising connecting ester bridges, ether bridges, hydroxy groups, and associative groups that represent at least 60 wt.% of the polymer network. The polymer network including connecting ester bonds is obtained by contacting at least one thermosetting resin precursor (P1) comprising hydroxy functions and/or epoxy groups, and optionally ester functions with: at least one hardener (D1) comprising carboxylic acids and acid anhydrides; and optionally at least one compound (C1) comprising on the one hand at least one associative group, and on the other hand at least a function which permits its grafting on the precursor (P1), on the curing agent (D1) or on the product resulting from the reaction of (P1) and (D1), in the presence of at least one transesterification catalyst. The polymer network comprises less than 4 wt.% of groups comprising -S-S- (disulfur) and -(S)n- (polysulfur, where n is greater that n 2) bridges. Preferred Components: The thermally conductive filler is: electrically insulative; and one of aluminum nitride, boron nitride, magnesium silicon nitride, silicon carbide and/or ceramic-coated graphite. The total molar amount of transesterification catalyst is 5-25% of the total molar amount of connecting ester bonds contained in the polymer network. The catalyst is one of metal salts such as salts of zinc, tin, magnesium, cobalt, calcium, titanium and zirconium. The compound (C1) is of formula (A1-L1-R1). The associative group is one of moiety of formula (I), 4H-1,2,4-triazol-4-yl, 1H-1,2,4-triazol-3-yl, or 6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl, where the bond represented by a circular arc between NH and N in (I) is -CH2-CH2-, -CH=CH-, or -NH-CH2-.A1 = associative group capable of forming hydrogen bonds;L1 = linking arm comprising aryl, aralkyl, alkane poly-yl, alkene poly-yl groups, optionally interrupted by at least one group comprising ether bridge, amine bridge, thioether bridge, amide bridge, ester bridge, urea bridge, urethane bridge, anhydride bridge, carbonyl bridge, where L1 contains 1-50C and up to 6 heteroatoms;R1 = function comprising alcohol, amine (NH, NH2), or carboxylic acid; andY1 = O, S or NH. EXAMPLE - No suitable example given.