Microparticles which: a. are non-porous that is to mean that the microparticles have a porosity determined via mercury porosimetry according to ISO 15901-1:2005, of at most 10 %; and b. comprise a thermosetting polymeric network matrix which thermosetting polymeric network matrix comprises building groups selected from the group consisting of ester groups, ether groups, amide groups, urethane groups, and combinations thereof, and c. have a random architecture, that is to mean that the microparticles have neither a core-shell architecture, nor a multi-layered architecture, nor an occluded architecture, nor a partially engulfed architecture, nor any combination thereof, and d. have a particle size distribution with a median particle size by volume Dv50 as determined via laser diffraction according to the ISO 13320:2009, of at least 1 and at most 850, preferably at least 1 and at most 350, more preferably at least 1 and at most 300, most preferably at least 1 and at most 250, especially at least 1 and at most 200, more especially at least 1 and at most 150, even more especially at least 1 and at most 100, most especially at least 1 and at most 50, for example at least 1 and at most 30 μm, and e. do not have a melting temperature (T m) as determined via Differential Scanning Calorimetry according to the description, and f. have a glass transition temperature (T g) as determined via rheometry according to the description, of at least 45 and at most 150, preferably at least 50 and at most 150, more preferably at least 60 and at most 150, most preferably at least 70 and at most 150 °C, and g. have a storage modulus G' at 130 °C as determined via rheometry according to the description, of at least 10 5 Pa.s and at most 10 9 Pa.s, and h. have a rubbery plateau between 130 and 200 °C -as this is defined in the description and as determined via rheometry according to the description-, and i. have a sphericity S 50 as determined according to the ISO 13322-2:2006 of at least 0.05 and at most 0.95, and j. have an aspect ratio A 50 as determined according to the ISO 13322-2:2006 of at least 0.05 and at most 0.95, and k. have a convexity C 50 as determined according to the ISO 13322-2:2006 of at least 0.05 and at most 0.95, and l. have a Brunauer-Emmett-Teller specific surface as determined according to the ISO 9277:2010, of at least 0.01 and at most 15 m 2 /g, and m. have an aerobic char yield at 600 °C, as determined via pyrolysis according to the description of at most 70, preferably at most 60, more preferably at most 50, even more preferably at most 40 % w/w on microparticles. a. are non-porous that is to mean that the microparticles have a porosity determined via mercury porosimetry according to ISO 15901-1:2005, of at most 10 %; and b. comprise a thermosetting polymeric network matrix which thermosetting polymeric network matrix comprises building groups selected from the group consisting of ester groups, ether groups, amide groups, urethane groups, and combinations thereof, and c. have a random architecture, that is to mean that the microparticles have neither a core-shell architecture, nor a multi-layered architecture, nor an occluded architecture, nor a partially engulfed architecture, nor any combination thereof, and d. have a particle size distribution with a median particle size by volume Dv50 as determined via laser diffraction according to the ISO 13320:2009, of at least 1 and at most 850, preferably at least 1 and at most 350, more preferably at least 1 and at most 300, most preferably at least 1 and at most 250, especially at least 1 and at most 200, more especially at least 1 and at most 150, even more especially at least 1 and at most 100, most especially at least 1 and at most 50, for example at least 1 and at most 30 μm, and e. do not have a melting temperature (T m) as determined via Differential Scanning Calorimetry according to the description, and f. have a glass transition temperature (T g) as determined via rheometry according to the description, of at least 45 and at most 150, preferably at least 50 and at most 150, more preferably at least 60 and at most 150, most preferably at least 70 and at most 150 °C, and g. have a storage modulus G' at 130 °C as determined via rheometry according to the description, of at least 10 5 Pa.s and at most 10 9 Pa.s, and h. have a rubbery plateau between 130 and 200 °C -as this is defined in the description and as determined via rheometry according to the description-, and i. have a sphericity S 50 as determined according to the ISO 13322-2:2006 of at least 0.05 and at most 0.95, and j. have an aspect ratio A 50 as determined according to the ISO 13322-2:2006 of at least 0.05 and at most 0.95, and k. have a convexity C 50 as determined according to the ISO 13322-2:2006 of at least 0.05 and at most 0.95, and l. have a Brunauer-Emmett-Teller specific surface as determined according to the ISO 9277:2010, of at least 0.01 and at most 15 m 2 /g, and m. have an aerobic char yield at 600 °C, as determined via pyrolysis according to the description of at most 70, preferably at most 60, more preferably at most 50, even more preferably at most 40 % w/w on microparticles.