Self-assembled nanoparticles have applications in a wide range of fields, including their use in the fabrication of nanowires for electronic devices [1] and the detection of DNA sequences associated with biological agents [2]. Functional groups are often added to these particles to induce or promote the desired aggregation behavior [2,3]. We perform Monte Carlo simulations in the grand canonical ensemble to study nanoparticles (which occupy several sites on a cubic lattice) functionalized with flexible chains. In our previous work, we have shown that spherical nanoparticles with an attractive interaction between adjacent segments and a single athermal chain undergo phase separation into a dilute and lamellar phase if the volume occupied by the chain is less that that occupied by the nanoparticle, and otherwise form micelles. Herein, we study multiple attached chains with an attraction of unit strength between nearest neighbor segments and non-interacting nanoparticles. Histogram reweighting methods are used to quantify and distinguish between first-order phase transitions and the formation of finite-sized aggregates [4,5]. We examine the effect of nanoparticle size and shape and the number and length of chains attached on the phase behavior of these systems and determine the temperature dependence of the critical micellar concentration.

[1] Lopes, W.A., Phys. Rev. E 65, 031606 (2002).

[2] Mirkin, C.A., Inorg. Chem. 39, 2258-2272 (2000).

[3] Carroll, J.B., Frankamp, B.L., Rotello, V.M., Chem. Comm. 17, 1892-1893 (2002).

[4] Floriano, M.A., Caponetti, E., Panagiotopoulos, A.Z., Langmuir 15, 3143-3151 (1999).

[5] Panagiotopoulos, A.Z., Floriano, M.A., Kumar, S.K., Langmuir 18, 2940-2948 (2002).