A photoactuating nanocomposite was prepared by the in situ grafting of carbon nanotubes with PBA-b-PMMA diblock copolymer during the synthesis of the linear triblock copolymer poly(methyl methacrylate)-b-poly(nbutyl acrylate)-b-poly(methyl methacrylate) (PMMA-b-PBA-b-PMMA). Control over the molecular characteristics of the block copolymers was achieved by applying atom transfer radical polymerization. This synthetic approach allowed for the excellent dispersion and distribution of carbon nanotubes within the polymer matrix. The final nanocomposite containing 1 wt % grafted carbon nanotubes exhibited improved elasticity compared to that of the pure triblock copolymer, as demonstrated by dynamic mechanical analysis and rotational rheology measurements. The photoactuating behavior of the nanocomposite was demonstrated by thermomechanical analysis.A crylic block copolymers exhibit interesting properties that can be tuned by manipulating the structure and length of the blocks. The combination of polyacrylate soft block with polymethacrylate hard blocks in ABA triblock copolymers can provide materials with the properties of thermoplastic elastomers (TPEs). Compared to widely commercially used isoprene-or butadiene-containing TPEs, acrylic TPEs pose several advantages. Due to the absence of unsaturated bonds in the main chain, the acrylic-based block copolymers are more resistant to UV light. 1 In addition, versatile (meth)acrylic monomers allow for the service temperature to be tuned over a wide range of T g , from approximately −50 to 200°C. 2,3 Currently, reversible-deactivation radical polymerization (RDRP) 4a (also called controlled/living 4b and quasiliving 4c ) techniques are widely used for the preparation of block copolymers. 5−7 Among the different RDRP techniques that are available, atom transfer radical polymerization (ATRP) is considered the most versatile because it enables good control over the polymerization of acrylic, methacrylic, and styrene monomers. 8−10 ATRP has been successfully employed for the synthesis of a wide range of block copolymers with TPE properties. 11,12 In addition to linear block copolymers, block copolymers with star-like, 11−13 brush, 14 or branched 15 architectures have been synthesized. The properties of these copolymers differ from those of their linear analogues. For example, star-like copolymers exhibit better tensile strength and elongation at break than three-arm and linear copolymers with similar compositions. 11,12The incorporation of carbon nanotubes (CNTs) into a TPE matrix can lead to the improvement of certain material characteristics, such as electrical conductivity, mechanical properties, or photoactuation performance. 16−19 The dispersion and distribution of CNT in a polymer matrix remain key factors in the preparation of nanocomposites. It is well-known that CNTs tend to agglomerate into clusters that due to bad stress transfer from the matrix to the filler cause a deterioration of the final material's mechanical properties. In the case of photoactuating TPE nano...