Micellization Behaviour of Linear and Nonlinear Block Copolymers Based on Poly(n-hexyl isocyanate) in Selective Solvents

Abstract

Block copolymers have attracted significant scientific and economic interest over the last decades due to their ability to self-assemble into ordered structures both in bulk and in selective solvents. In this work, the self-assembly behaviour of both linear (diblocks, triblocks and pentablocks) and nonlinear (miktoarm stars and a block-graft) copolymers based on poly(n-hexyl isocyanate), PHIC, were studied in selective solvents such as n-heptane and n-dodecane. A variety of experimental techniques, namely static and dynamic light scattering, dilute solution viscometry and atomic force microscopy, were employed to study the micellar structural parameters (e.g., aggregation number, overall micellar size and shape, and core and shell dimensions). The effect of the macromolecular architecture, the molecular weight and the copolymer composition on the self-assembly behaviour was studied. Spherical micelles in equilibrium with clusters were obtained from the block copolymers. Thermally stable, uniform and spherical aggregates were found from the triblock copolymers. The poly(n-hexyl isocyanate)-b-polyisoprene-b-poly(n-hexyl isocyanate),-HIH copolymers tend to adopt closed loop conformation, leading to more elongated cylindrical-type structures upon increasing the concentration. Clustering effects were also reported in the case of the pentablock terpolymers. The topology of the blocks plays an important role, since the poly(n-hexyl isocyanate)-b-polystyrene-b-polyisoprene-b-polystyrene-b-poly(n-hexyl isocyanate), HSISH terpolymer shows intermicellar fusion of spherical micelles, leading to the formation of extended networks. The formation of spherical micelles in equilibrium with clusters was obvious in the case of the miktoarm stars, whereas the block-graft copolymer shows the existence of mainly unimolecular micelles.

High-performance family of polymeric particles prepared from poly(phenylene oxide)-poly(hexyl isocyanate) liquid crystal block copolymer: synthesis and properties study

“…The higher percentage of LC block in the structure, the higher tendency of the copolymer to form an anisotropic phase. 22,[25][26][27][28][29][30]32,39,50,54 The phase transition of the solution is a function of two parameters of temperature and concentration. The orientation change of LC molecules as a function of free energy and temperature was discussed by Guo et al 55 The effect of solution concentration (0.2, 0.4, and 0.6 mg/mL in toluene) and temperature (25-100°C) on the LC texture of samples was investigated.…”

“…Recently, poly (n-hexyl isocyanate) (PHIC) and its copolymers have attracted considerable attention because of their potential applications and unique properties in areas such as chiral recognitions, optical switches, liquid crystals, degradable materials, nanocomposites, blend of polymers, electrical devices, biomaterials, nanowires, thermoreversible gels, and activators. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] These copolymers are so important that various behaviors of linear and nonlinear block copolymers based on PHIC have been investigated by Vazaios et al 32 The known methods used for copolymerization of PHIC are reported in Table 1.…”

Synthesis and Characterization of Statistical and Block Copolymers of n-Hexyl Isocyanate and 3-(Triethoxysilyl) Propyl Isocyanate via Coordination Polymerization

“…Therefore, they may behave either as rigid rods or as semiflexible worm-like chains. Combination of PICs with other rigid or more flexible chains in diblock copolymers or more complex macromolecular architectures opens new horizons in nanotechnology focusing on the microphase separation, the ordering kinetics and the self-assembly behavior in solution [9][10][11]. Consequently, novel applications are expected to emerge, making these materials possible candidates as optical switches, recognition devices, etc.…”

Effect of Surfactant Molecular Structure on Emulsion Stability Investigated by Interfacial Dilatational Rheology

“…Polymeric surfactants are now used to control the emulsion rheology and applied in various industries like oil recovery [ 1 , 2 ], cosmetics [ 3 ] and drug delivery [ 4 ]. Generally, the stability of emulsion limits its application.…”