Photocontrol over the Disorder-to-Order Transition (DOT) in Thin Film of Polystyrene-\textit{block}-Poly(methyl methacrylate) Block Copolymers Containing Photodimerizable anthracene functionality

Reversible photocontrol over the disorder-to-order transition (DOT) of block copolymers can be used to fabricate defect-free, long-range ordered nanomaterials over macroscopic distances by ``photo-combing'' the microdomains. Here, we randomly copolymerized anthracene functionalities in a ``dilute'' way with 2-hydroxyethyl methacrylate as the middle block, forming deuterated polystyrene-\textit{block}-poly(2-(methacryloyloxy)ethyl anthracene-9-carboxylate-\textit{random}-2-hydroxyethyl methacrylate)-\textit{block}-poly(methyl methacrylate) ($d_{8}$-PS-$b$-P(9AnEMA-$r$-HEMA)-$b$-PMMA) triblock copolymers. Upon UV irradiation of a thin film of the phase-mixed triblock copolymer, photodimerization of anthracene links the junction of $d_{8}$-PS and PMMA blocks and produces an artificial interface to force a phase-separation, i.e. a UV-induced DOT, as evidenced by small angle neutron scattering (SANS). Reversible photocontrol over the DOT can be achieved by taking advantage of photodimerization and photodissociation of anthracene.