Scheme 1 a a Conditions: (a) synthesis scheme of R-vinyl-ω-(phenyl) end-functionalized P3HT; (b) R-vinyl-ω-(phenyl) end-functionalized P3HT is activated by s-BuLi and forms 3, which subsequently serves as an anionic macroinitiator for the synthesis of P3HT-P2VP; dppp ) propane-1,3-diylbis-(diphenylphosphane).

A series of poly(diethylhexyloxy-p-phenylenevinylene-b-methyl methacrylate) (DEH-PPVb-PMMA) polymers with narrow polydispersity (PDI < 1.1) were synthesized using Siegrist polycondensation and anionic polymerizations followed by "click" chemistry. Alkyne-terminated DEH-PPV and azidoterminated PMMA were synthesized first, and then the two functionalized polymers underwent 1,3-cycloaddition reaction to obtain copolymers. Both the conversion of the end-functionalization of the homopolymers and the yield of the "click" reaction were higher than 98% as determined by 1 H nuclear magnetic resonance ( 1 H NMR) and gel permeation chromatography (GPC). Transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) studies reveal the details of copolymer morphology. The DEH-PPV-b-PMMA system presented here has higher block segregation strength than many previously studied rod-coil block copolymers yet still shows experimentally accessible phase transitions with respect to temperature. As a result, this molecule offers new insight into the competition between rod-rod and rod-coil interactions that occurs in the system. The DEH-PPV rods are organized as a monolayer that is inclined with the lamellar normal (smectic C) for the copolymers containing low volume fraction of PMMA coil (<54%). However, as the coil fraction increases, the strips containing DEH-PPV pack into hexagonal lattice. In contrast to previous work which demonstrated similar morphologies, the sequence of reversible liquid crystalline and microphase phase transitions is altered as a result of the increased block segregation. Upon heating, the low coil fraction copolymers exhibit a series of clear transitions of smectic-lamellar to amorphous-lamellar to disordered structures. In high coil fraction copolymers, the transitions between smectic-hexagonal to amorphous-hexagonal and smectic-hexagonal to disorder structures could not be clearly differentiated. The order-to-disorder temperature (ODT) decreases slowly with increasing coil fraction while the smectic-to-isotropic transition (SI) temperature stays relatively unchanged. The steady SI temperature suggests that the strong rod-rod interaction keeps the liquid crystalline rod in the nanodomain structure regardless of the amount of coil segment in the copolymers.

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An ordered nanostructure can be created from the hybrid materials of self-assembly poly(3-hexyl thiophene-b-2-vinyl pyridine) and nicotinic acid-modified titanium dioxide nanoparticles (P3HT-b-P2VP/TiO(2)). TEM and XRD analyses reveal that the TiO(2) nanoparticles (NPs) are preferentially confined in the P2VP domain of P3HT-b-P2VP whereas TiO(2) NPs interact with either pure P3HT or a blend of P3HT and P2VP to produce microsized phase segregation. The morphologies of lamellar and cylindrical structures are disturbed when the loading of TiO(2) NPs is 40 wt % or higher. Cylindrical P3HT-b-P2VP/TiO(2) exhibits a small blue shift in absorption and photoluminescence spectra with increasing TiO(2) loading as compared to P3HT/TiO(2). The NPs cause a slightly misaligned P3HT domain in the copolymer. Furthermore, the PL quenching of P3HT-b-P2VP/TiO(2) becomes very large as a result of efficient charge separation in the ordered nanodomain at 16 nm. Solar cells fabricated from self-assembly P3HT-b-P2VP/TiO(2) hybrid materials exhibit a >30 fold improvement in power conversion efficiency as compared to the corresponding 0.3P3HT-0.7P2VP/TiO(2) polymer blend hybrid. This study paves the way for the further development of high-efficiency polymer-inorganic nanoparticle hybrid solar cells using a self-assembled block copolymer.