The reaction between oxazoline-functionalised polymer particles and bis(carboxylic acid)-terminated poly(tetrahydrofuran) (PTHF-COOH) was monitored by means of FTi.r. spectroscopy. Parameters such as particle size, content of functional groups, stoichiometry and temperature were varied to study their influence on conversion and reaction rate constants. Oxazoline conversion was primarily affected by particle size and less so by crosslink density. Reactions occurring at particle surfaces and in bulk of the particles were differentiated.