Block Copolymers Block copolymers are a fascinating class of polymeric materials belonging to a big family known as ‘‘soft materials.’’ This class of polymers is made by the covalent bonding of two or more polymeric chains that, in most cases, are thermodynamically incompatible giving rise to a rich variety of microstructures in bulk and in solution. The length scale of these microstructures is comparable to the size of the block copolymers molecules (typically 5–50 nm); therefore, the microstructures are highly coupled to the physical and chemical characteristics of the molecules. The variety of microstructures gives rise to materials with applications ranging from thermoplastic elastomers and high-impact plastics to pressure-sensitive adhesives, additives, foams, etc. In addition, block copolymers are very strong candidates for potential applications in advanced technologies such as information storage, drug delivery, and photonic crystals.

AB type block copolymers Four main synthetic routes have been developed (Figure 8.1) to prepare well-defined diblock copolymers with narrow molecular weight distribution and very low compositional heterogeneity.

ABA

ABC

Graft copolymers

Target Structure: Linear densely grafted copolymer Method: Functional monomer (protected), ATRP, Deprotection, Macroinitiator, ATRP Chemistry

Polymer 45 (2004) 8173–8179

Macromolecules 2005, 38,

Grafting to reactions require the coupling of individual preformed tele-functional side chain precursors to a backbone polymer with distributed complementary functionality. Grafting through consists of the polymerization of macromonomers. Grafting from involves preparing the precursor to the backbone polymer with monomer units that contain functionalities ultimately capable of initiating polymerization of a second monomer.

Aim: Stimuli-responsive Bottle-brush Polymer Macromol. Rapid Commun Kejian Yao, Ying Chen, Jun Zhang, Clay Bunyard, Chuanbing Tang Method Chemistry

Ring opening metathesis polymerization (ROMP)

Synthesis of Block-Copolymer via Crossover-Chemistry in ROMP Binder, Wolfgang Macromolecules 2009

Monofunctional Metathesis Polymers via Sacrificial Diblock Copolymers Angew. Chem. Int. Ed. 2006, 45, 8045 –8048

“Perfect Comb” ADMET Graft Copolymers Macromolecules 2001, 34,

Macrocyclization of Polymers via Ring-Closing Metathesis and Azide/Alkyne-‘‘Click’’- Reactions: Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 48, 671–680 (2010)