Directed polymerization method to generate complex, three dimensional (3D) structures in soft materials

A method of forming a 3-dimensional structure from a hydrogel polymerisation solution, the process comprising the steps of:

• (a) placing a hydrogel polymerisation solution into a reaction vessel, where the hydrogel polymerisation solution comprises a solvent, a polymerisation initiator and:
• a monomer, polymer or oligomer and a crosslinking agent chemically compatible with said monomer, polymer or oligomer;
• and/or
• a polymer or oligomer suitable for self-crosslinking upon exposure to the polymerisation initiator;
• and
• (b) allowing the hydrogel polymerisation solution to react without mixing for a period of time at ambient temperature, while introducing a polymerisation modulator to the hydrogel polymerisation solution through a hydrogel polymerisation solution/polymerisation modulator interface, wherein
• over the period of time, a modulation effect gradient is established in the hydrogel polymerisation solution, where the modulation effect has a maximal value at the hydrogel polymerisation solution/polymerisation modulator interface and a minimal value at a point furthest away from said interface, wherein one or both of the following apply:
• (i) one or more hydrophilic physical constraint members are added to the reaction vessel in step (a), wherein the one or more hydrophilic physical constraint members reduce growth of polymer in step (b) in a region abutting or adjacent to the one or more hydrophilic physical constraint members;
• and
• (ii) the reaction vessel has a surface and one or more regions of the surface are treated with a chemical constraint material that reduces or completely inhibits growth of polymer in step (b) on or adjacent to each region of the surface so treated by forming a covalent bond with a growing polymeric material.