Three-dimensional printing combining ring-opening metathesis polymerization and free radical polymerization

A method of fabricating a three-dimensional object, the method comprising sequentially forming a plurality of layers in a configured pattern corresponding to a shape of the object, thereby forming the object,

• wherein forming at least one of said layer comprises:
• (i) dispensing by at least one inkjet printing head at least one modeling material formulation, said at least one modeling material formulation comprising:
• an unsaturated cyclic monomer polymerizable by ring opening metathesis polymerization (ROMP);
• a catalyst or a catalyst system comprising a catalyst for initiating ROMP of said monomer;
• a curable material polymerizable by free-radical polymerization (FRP);
• and
• a curing agent for initiating free radical polymerization of said curable material;
• (ii) exposing said at least one modeling material formulation to a condition for inducing initiation of ROMP of said monomer by said catalyst;
• (iii) maintaining said formulation at a first temperature for a first time period, wherein said first time period is such that at least 80% of said unsaturated cyclic monomer undergo polymerization by said ROMP during said first time period;
• and
• (iv) subsequent to said first time period, exposing the modeling material formulation to a condition for inducing initiation of free-radical polymerization of said curable material by said curing agent, said condition for inducing initiation of said free radical polymerization comprising a second temperature, wherein said second temperature is higher than said first temperature, and wherein said curing agent is a thermally-activatable curing agent that is activated at said second temperature,
• to thereby obtain a cured modeling material in said layer.