Synthesis and self‐assembly of helical polypeptide‐random coil amphiphilic diblock copolymer

Three amphiphilic rod‐coil diblock copolymers, poly(2‐ethyl‐2‐oxazoline‐b‐γ‐benzyl‐L ‐glutamate) (PEOz‐b‐PBLG), incorporating the same‐length PEOz block length and various lengths of their PBLG blocks, were synthesized through a combining of living cationic and N‐carboxyanhydride (NCA) ring‐opening polymerizations. In the bulk, these block copolymers display thermotropic liquid crystalline behavior. The self‐assembled aggregates that formed from these diblock copolymers in aqueous solution exhibited morphologies that differed from those obtained in α‐helicogenic solvents, that is, solvents in which the PBLG blocks adopt rigid α‐helix conformations. In aqueous solution, the block copolymers self‐assembled into spherical micelles and vesicular aggregates because of their amphiphilic structures. In helicogenic solvents (in this case, toluene and benzyl alcohol), the PEOz‐b‐PBLG copolymers exhibited rod‐coil chain properties, which result in a diverse array of aggregate morphologies (spheres, vesicles, ribbons, and tube nanostructures) and thermoreversible gelation behavior. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3108–3119, 2008     

Synthesis and self‐assembly of fluorinated block copolymers

Fluorinated block copolymers combine the unique properties of fluoropolymers and the intriguing self‐assembly of hybrid macromolecules. The preparation of the title molecules by selective fluorination procedures and the effect of fluorine incorporation on the material thermodynamics are presented. We highlight two fluorination schemes developed in our laboratory, difluorocarbene and perfluoroalkyliodide additions to polydienes, that allow for the selective and tunable incorporation of different fluorinated groups into model block copolymers. The fluorination changes the physical properties of the parent materials and leads to interesting changes in the component incompatibilities. The role of fluorination in determining block copolymer thermodynamics in both the solid state and in solution and in ultimately exploiting fluorination to produce novel, higher order structures is central to our research efforts. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 1–8, 2002     

Synthesis,characterization, and self‐assembly of comb‐dendronized amphiphilic block copolymers

Novel amphiphilic comb‐dendronized diblock copolymers composed of hydrophobic Percec‐type dendronized polystyrene block and hydrophilic comb‐like poly(ethylene oxide) grafted polymethacrylate P(PEOMA) block were designed and synthesized via two steps of atom transfer radical polymerization (ATRP). The comb‐like P(PEOMA) prepared by ATRP of macromonomers (PEOMA) with two different molecular weights (M_n = 300 and 475) were used to initiate the sequent ATRP of dendritic styrene macromonomer (DS). The molecular weights and compositions of the obtained block copolymers were determined by ¹H NMR analysis. The copolymers with relatively narrow polydispersities (1.27–1.38) were thus obtained. The bulk properties of comb‐dendronized block copolymers were studied by using differential scanning calorimetry, polarized optical microscopy and wide‐angle X‐ray diffraction (WAXD). Similar to dendronized homopolymers, the block copolymers exhibited hexagonal columnar liquid‐crystalline phase structure. By using such amphiphilic comb‐dendronized block copolymers as building blocks, the rich self‐assembly morphologies, such as twisted string, vesicle, and large compound micelle (LCM), were obtained in a mixture of CH₃OH and THF. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4205–4217, 2008     

Synthesis,self‐assembly,and thermosensitivity of amphiphilic POEGMA‐PDMS‐POEGMA triblock copolymers

In this article, the synthesis and self‐assembly of a novel well‐defined biocompatible amphiphilic POEGMA‐PDMS‐POEGMA triblock copolymer were studied. The copolymer was synthesized by atom transfer radical polymerization of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) using α,ω‐dibromo polydimethylsiloxane macroinitiator (Br‐PDMS‐Br). Br‐PDMS‐Br was synthesized through the esterification of α,ω‐hydroxypropyl polydimethylsiloxane and 2‐bromoisobutyryl bromide. The structures of the copolymers were confirmed by proton nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The copolymers showed reversible aggregation in response to temperature cycles with a lower critical solution temperature (LCST) between 61 and 66 °C, as determined by ultraviolet‐visible spectrophotometry and dynamic light scattering. The LCST values increased in proportion to the length of the hydrophilic block and were lower than that of the POEGMA homopolymer. The self‐assembly behavior of the copolymers in aqueous solution was investigated by fluorescence spectroscopy and transmission electron microscopy. The critical micelle concentration value (1.08–0.26 10^?6 mol L^?1) decreased as the length of the POEGMA chain increased. The POEGMA‐PDMS‐POEGMA copolymers can easily self‐assemble into spherical micelles in aqueous solution. Such biocompatible block copolymers may be attractive candidates as ‘‘smart'' thermo‐responsive drug delivery systems. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2684‐2691     

Reduction and pH dual‐responsive block copolymers containing pendent p‐nitrobenzyl carbamate functionalities: Synthesis and self‐assembly behavior

We report on the preparation of reduction‐responsive amphiphilic block copolymers containing pendent p‐nitrobenzyl carbamate (pNBC)‐caged primary amine moieties by reversible addition–fragmentation chain transfer (RAFT) radical polymerization using a poly(ethylene glycol)‐based macro‐RAFT agent. The block copolymers self‐assembled to form micelles or vesicles in water, depending on the length of hydrophobic block. Triggered by a chemical reductant, sodium dithionite, the pNBC moieties decomposed through a cascade 1,6‐elimination and decarboxylation reactions to liberate primary amine groups of the linkages, resulting in the disruption of the assemblies. The reduction sensitivity of assemblies was affected by the length of hydrophobic block and the structure of amino acid‐derived linkers. Using hydrophobic dye Nile red (NR) as a model drug, the polymeric assemblies were used as nanocarriers to evaluate the potential for drug delivery. The NR‐loaded nanoparticles demonstrated a reduction‐triggered release profile. Moreover, the liberation of amine groups converted the reduction‐responsive polymer into a pH‐sensitive polymer with which an accelerated release of NR was observed by simultaneous application of reduction and pH triggers. It is expected that these reduction‐responsive block copolymers can offer a new platform for intracellular drug delivery. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1333–1343     

Synthesis and self‐assembly of stimuli‐responsive amphiphilic block copolymers based on polyhedral oligomeric silsesquioxane

A novel POSS‐containing methacrylate monomer (HEMAPOSS) was fabricated by extending the side chain between polyhedral oligomeric silsesquioxane (POSS) unit and methacrylate group, which can efficiently decrease the steric hindrance in free‐radical polymerization of POSS‐methacrylate monomer. POSS‐containing homopolymers (PHEMAPOSS) with a higher degree of polymerization (DP) can be prepared using HEMAPOSS monomer via reversible addition–fragmentation chain transfer (RAFT) polymerization. PHEMAPOSS was further used as the macro‐RAFT agent to construct a series of amphiphilic POSS‐containing poly(N, N‐dimethylaminoethyl methacrylate) diblock copolymers, PHEMAPOSS‐b‐PDMAEMA. PHEMAPOSS‐b‐PDMAEMA block copolymers can self‐assemble into a plethora of morphologies ranging from irregular assembled aggregates to core‐shell spheres and further from complex spheres (pearl‐necklace‐liked structure) to large compound vesicles. The thermo‐ and pH‐responsive behaviors of the micelles were also investigated by dynamic laser scattering, UV spectroscopy, SEM, and TEM. The results reveal the reversible transition of the assembled morphologies from spherical micelles to complex micelles was realized through acid‐base control. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2669‐2683     

Novel hepatoma‐targeting micelles based on chemoenzymatic synthesis and self‐assembly of galactose‐functionalized ribavirin‐containing amphiphilic random copolymer

Hepatoma‐targeting micelles were successfully prepared by self‐assembly of galactose‐functionalized ribavirin‐containing amphiphilic random copolymer as novel drug delivery vehicles. The ribavirin‐containing random copolymer with galactose as the targeting ligand was facilely synthesized by combining enzymatic transesterification with radical polymerization and fully characterized by FTIR, NMR, and GPC. The formation of micelle‐type aggregates from the random copolymer was verified by UV–vis and fluorescence spectroscopy using pyrene as the guest molecule. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) experiments revealed that the micelles were well dispersed as spherical nanoparticles in water, whose hydrodynamic diameter was 217 ± 19 nm. Their biological recognition to fluorescein‐labeled peanut agglutinin investigated by confocal laser scanning microscopy (CLSM) proved the existence of hydrophilic galactose targeting moieties on the surface of micelles. Cell cytotoxicity tests and the inhibition experiment of galactose performed by MTT assay showed that the micelles had evident targeting function to hepG2 cells and the galactose moieties on the surface of micelles mediated cellar uptake of micelles. In vitro release studies indicated that ribavirin could be slowly released from the copolymer with pseudo zero‐order kinetics. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2734–2744, 2008     

Spontaneous formation of narrowly‐distributed self‐assembly from polyamidoamine dendron‐poly(L‐lysine) block copolymers through helix‐coil transition of poly(L‐lysine) block

The self‐assembly of head‐tail type block copolymers composed of polyamidoamine dendron head block and poly(L ‐lysine) (PLL) tail block was studied using a light scattering technique and transmission electron microscopy. A PLL tail block in a head‐tail type block copolymer exhibits a coil‐to‐helix transition as a result of the change in solvent quality from water to methanol. When the PLL tail block takes a helical conformation in high methanol content, the resulting head‐tail type block copolymer has a defined three‐dimensional structure like that of a protein molecule. Self‐assemblies of such block copolymers having a totally fixed molecular shape spontaneously form polymersome‐like self‐assemblies with an extremely narrow size distribution through converging to a thermodynamically stable assembling state. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1217–1223, 2009     

Amphiphilic star‐block copolymers based on a hyperbranched core: Synthesis and supramolecular self‐assembly

Novel amphiphilic star‐block copolymers, star poly(caprolactone)‐block‐poly[(2‐dimethylamino)ethyl methacrylate] and poly(caprolactone)‐block‐poly(methacrylic acid), with hyperbranched poly(2‐hydroxyethyl methacrylate) (PHEMA–OH) as a core moiety were synthesized and characterized. The star‐block copolymers were prepared by a combination of ring‐opening polymerization and atom transfer radical polymerization (ATRP). First, hyperbranched PHEMA–OH with 18 hydroxyl end groups on average was used as an initiator for the ring‐opening polymerization of ε‐caprolactone to produce PHEMA–PCL star homopolymers [PHEMA = poly(2‐hydroxyethyl methacrylate); PCL = poly(caprolactone)]. Next, the hydroxyl end groups of PHEMA–PCL were converted to 2‐bromoesters, and this gave rise to macroinitiator PHEMA–PCL–Br for ATRP. Then, 2‐dimethylaminoethyl methacrylate or tert‐butyl methacrylate was polymerized from the macroinitiators, and this afforded the star‐block copolymers PHEMA–PCL–PDMA [PDMA = poly(2‐dimethylaminoethyl methacrylate)] and PHEMA–PCL–PtBMA [PtBMA = poly(tert‐butyl methacrylate)]. Characterization by gel permeation chromatography and nuclear magnetic resonance confirmed the expected molecular structure. The hydrolysis of tert‐butyl ester groups of the poly(tert‐butyl methacrylate) blocks gave the star‐block copolymer PHEMA–PCL–PMAA [PMAA = poly(methacrylic acid)]. These amphiphilic star‐block copolymers could self‐assemble into spherical micelles, as characterized by dynamic light scattering and transmission electron microscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6534–6544, 2005     

Synthesis of miktoarm star amphiphilic block copolymers via combination of NMRP and ATRP and investigation on self‐assembly behaviors

The novel trifunctional initiator, 1‐(4‐methyleneoxy‐2,2,6,6‐tetramethylpip‐eridinoxyl)‐3,5‐bi(bromomethyl)‐2,4,6‐trimethylbenzene (TEMPO‐2Br), was successfully synthesized and used to prepare the miktoarm star amphiphilic poly(styrene)‐(poly(N‐isopropylacrylamide))₂ (PS(PNIPAAM)₂) via combination of atom transfer radical polymerization (ATRP) and nitroxide‐mediated radical polymerization (NMRP) techniques. Furthermore, the star amphiphilic block copolymer, poly (styrene)‐(poly(N‐isopropylacrylamide‐b‐4‐vinylpyridine))₂ (PS(PNIPAAM‐b‐P4VP)₂), was also prepared using PS(PNIPAAM)₂ as the macroinitiator and 4‐vinylpyridine as the second monomer by ATRP method. The obtained polymers were well‐defined with narrow molecular weight distributions (M_w/M_n ≤ 1.29). Meanwhile, the self‐assembly behaviors of the miktoarm amphiphilic block copolymers, PS(PNIPAAM)₂ and PS(PNIPAAM‐b‐P4VP)₂, were also investigated. Interestingly, the aggregate morphology changed from sphere‐shaped micelles (4.7 < pH < 3.0) to a mixture of spheres and rods (1.0 < pH < 3.0), and rod‐shaped nanorods formed when pH value was below 1.0. The LCST of PS(PNIPAAM)₂ (pH = 7) was about 31 °C and the LCST of PS(PNIPAAM‐b‐P4VP)₂ was about 35 °C (pH = 3). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6304–6315, 2009     

Advances in square arrays through self‐assembly and directed self‐assembly of block copolymers

This review covers recent advances in developing square arrays in thin films using block copolymers. Theoretical and experimental results from self‐assembly of block copolymers in bulk and thin films, directed self‐assembly of block copolymers confined in small wells, on substrates with arrays of posts, and on chemically nanopatterned substrates, as well as applications as nanolithography are reviewed. Some future work and hypothesis are discussed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Hybrid amphiphilic block copolymers containing polyhedral oligomeric silsesquioxane: Synthesis,characterization, and self‐assembly in solutions

In this article, the amphiphilic block copolymers containing polyhedral oligomeric silsesquioxane (POSS), namely PMAPOSS‐b‐PAA and PMAPOSS‐b‐P(AA‐co‐St), were synthesized consecutively by reversible addition–fragmentation chain transfer and selective hydrolysis, and characterized by ¹H NMR, ¹³C NMR, Fourier transform infrared spectroscopy and gel permeation chromatography. In the presence of the nearly gradient styrene distribution along the hydrophilic block with a feed molar ratio of tert‐butyl acrylate (tBA) to St being 10/1, patterned core‐corona nanoparticles (NPs) were formed from the mixture of good/selective solvents (THF/water) by a simple evaporation process at room temperature. With the extending of the co‐block length, the self‐assembled NPs exhibited phase separation behavior of spheres‐dispersed, onion‐like and onion‐cluster hierarchical structures in turn. However, while a change in the feed molar ratio occurred, it resulted in the formation of typical core‐shell micelles (20/1, tBA/St) and disordered particles (5/1, tBA/St), respectively. Furthermore, the self‐assembly behavior of PMAPOSS‐b‐P(AA‐co‐St) in DMF was investigated, which showed that it could perform a mixture morphology of well‐dispersive sphere micelles and large aggregate of micelles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and self‐assembly of amphiphilic macrocyclic block copolymer topologies

We demonstrated the synthesis of miktoarm star block copolymers of AB, AB₂, and A₂B, in which block A consisted of linear poly(tert‐butyl acrylate) (P^tBA) and block B consisted of cyclic polystyrene. These structures were produced using the atom transfer radical polymerization to make telechelic polymers that, after modification, were further coupled together by copper‐catalyzed “click” reactions with high coupling efficiency. Deprotection of P^tBA to poly(acrylic acid) (PAA) afforded amphiphilic miktoarm structures that when micellized in water gave vesicle morphologies when the block length of PAA was 21 units. Increasing the PAA block length to 46 units produced spherical core‐shell micelles. AB₂ miktoarm stars packed more densely into the core compared to its linear counterpart (i.e., a four times greater aggregation number with approximately the same hydrodynamic diameter), resulting in the PAA arms being more compressed in the corona and extending into the water phase beyond its normal Gaussian chain conformation. These results show that the cyclic structure attached to an amphiphilic block has a significant influence on increasing the aggregation number through a greater packing density. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Vesicular and tubular structures prepared from self‐assembly of novel amphiphilic ABA triblock copolymers in aqueous solutions

A kind of novel soft amphiphilic ABA triblock copolymers, poly(L ‐lysine)‐b‐poly(tetrahydrofuran)‐b‐poly(L ‐lysine), was synthesized by the anionic ring‐opening polymerization of ε‐benzyloxycarbonyl‐L ‐lysine N‐carboxyanhydride using amine‐terminated poly(tetrahydrofuran) as a macroinitiator and subsequent removal of the protecting group. The resulting copolymers possessing a nearly symmetrical and narrow molecular weight distribution were dissolved in water at an appropriate concentration range at room temperature to yield vesicles as confirmed by using negative stain TEM and DLS. Meanwhile, nanotubes were obtained as the result of the conjunction of vesicles by reducing the medium temperature as evidenced by TEM. The effect of pH and salt concentration variations on the self‐assembly behavior was also examined. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1042–1050, 2008     

Self‐assembly of amphiphilic ABA random triblock copolymers in water

Self‐assembly of amphiphilic ABA random triblock copolymers in water serves as a novel approach to create unique structure micelles connected with flexible linkages. The ABA triblock copolymers consist of amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) and hydrophobic dodecyl pendants as the A segments and a hydrophilic poly(ethylene oxide) (PEO) as the middle B segment. The A block is varied in dodecyl methacrylate content of 20%–50% and degree of polymerization (DP) of 100‐200. By controlling the composition and DP of the A block, various architectures can be tailor‐made as micelles in water: PEO‐linked double core unimer micelles, PEO‐looped unimer or dimer micelles, and multichain micelles. Those PEO‐linked or looped micelles further exhibit thermoresponsive solubility in water. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 313–321     

Synthesis,self‐assembly,fluorescence, and thermosensitive properties of star‐shaped amphiphilic copolymers with porphyrin core

Star‐shaped amphiphilic poly(ε‐caprolactone)‐block‐poly(oligo(ethylene glycol) methyl ether methacrylate) with porphyrin core (SPPCL‐b‐POEGMA) was synthesized by combination of ring‐opening polymerization (ROP) and atom transfer radical polymerization (ATRP). Star‐shaped PCL with porphyrin core (SPPCL) was prepared by bulk polymerization of ε‐caprolactone (CL) with tetrahydroxyethyl‐terminated porphyrin initiator and tin 2‐ethylexanote (Sn(Oct)₂) catalyst. SPPCL was converted into SPPCLBr macroinitiator with 2‐bromoisobutyryl bromide. Star‐shaped SPPCL‐b‐POEGMA was obtained via ATRP of oligo(ethylene glycol) methyl ether methacrylate (OEGMA). SPPCL‐b‐POEGMA can easily self‐assemble into micelles in aqueous solution via dialysis method. The formation of micellar aggregates were confirmed by critical micelle formation concentration, dynamic light scattering, and transmission electron microscopy. The micelles also exhibit property of temperature‐induced drug release and the lower critical solution temperature (LCST) was 60.6 °C. Furthermore, SPPCL‐b‐POEGMA micelles can reversibly swell and shrink in response to external temperature. In addition, SPPCL‐b‐POEGMA can present obvious fluorescence. Finally, the controlled drug release of copolymer micelles can be achieved by the change of temperatures. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis,characterization, and aqueous self‐assembly of amphiphilic poly(ethylene oxide)‐functionalized hyperbranched fluoropolymers

Complex amphiphilic polymers were synthesized via core‐first polymerization followed by alkylation‐based grafting of poly(ethylene oxide) (PEO). Inimer 1‐(4′‐(bromomethyl)benzyloxy)‐2,3,5,6‐tetrafluoro‐4‐vinylbenzene was synthesized and subjected to atom transfer radical self‐condensing vinyl polymerization to afford hyperbranched fluoropolymer (HBFP) as the hydrophobic core component with a number‐averaged molecular weight of 29 kDa and polydispersity index of 2.1. The alkyl halide chain ends on the HBFP were allowed to undergo reaction with monomethoxy‐terminated poly(ethylene oxide) amine (PEO_x‐NH₂) at different grafting numbers and PEO chain lengths to afford PEO‐functionalized HBFPs [(PEO_x)_y‐HBFPs], with x = 15 while y = 16, 22, or 29, x = 44 while y = 16, and x = 112 while y = 16. The amphiphilic, grafted block copolymers were found to aggregate in aqueous solution to give micelles with number‐averaged diameters (D_av) of 12–28 nm, as measured by transmission electron microscopy (TEM). An increase of the PEO:HBFP ratio, by increase in either the grafting densities (y values) or the chain lengths (x values), led to decreased TEM‐measured diameters. These complex, amphiphilic (PEO_x)_y‐HBFPs, with tunable sizes, might find potential applications as nanoscopic biomedical devices, such as drug delivery vehicles and ¹⁹F magnetic resonance imaging agents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3487–3496, 2010     

Synthesis and self‐assembly in water of coil‐rod‐coil amphiphilic block copolymers with central π‐conjugated sequence

The purpose of this study is to correlate the nano‐organization in water of coil‐rod‐coil amphiphilic block copolymers constituted of a conjugated segment to their optoelectronic properties. The ABA block copolymer structures, easily achieved via coupling reactions, are based on conjugated rod of dihexylfluorene and 3,4‐ethylenedioxythiophene units linked to two flexible poly(ethylene oxide) or poly[(ethylene oxide)‐ran‐(propylene oxide)] chains. These well‐defined copolymers exhibited a range of specific morphologies in water, a good solvent of coil blocks and a bad solvent of the conjugated rod. Particularly, vesicles and micelles with spherical, cylindrical, or elongated shape were noticed. Correlations were attempted to be established between the weight percent of the conjugated sequence contained in the copolymers, the morphology of the nanostructures obtained by self‐assembly in solution and the resulting optical properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4602–4616, 2008     

Synthesis and self‐assembly of polyhydroxylated and electropolymerizable block copolymers

A facile synthetic strategy for preparing hydroxylated polymethacrylate amphiphilic block copolymers (PCzMMA‐b‐PBMMA, PFlMMA‐b‐PBMMA) incorporated with primary and secondary hydroxyl groups and electroactive moieties along the polymer backbone is reported. Full characterization, structure‐property relationship and self‐assembly of these polymers are discussed. Due to interplay of hydrophobic/hydrophilic interactions, PCzMMA‐b‐PBMMA formed a layered lattice and PFlMMA‐b‐PBMMA showed a vesicular morphology. Electropolymerization of the electroactive units led to the formation of cross‐conjugated polymer network in solution and in thin films. The network structure was characterized with a range of spectroscopic techniques. Such highly processable polymers may be of interest to applications in which a conducting amphiphilic films with strong adhesion to various substrates are required. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2217–2227     

Synthesis and self‐assembly of rod‐coil molecules with n‐shaped rod building block

The rod‐coil molecules with n‐shaped rod building block, consisting of an anthracene unit and two biphenyl groups linked together with acetylenyl bonds at the 1,8‐position of anthracene as a rigid rod segment, and the alkyl or alkyloxy chains with various length (i.e., methoxy‐ ( 1 ), octyl‐ ( 2 ), hexadecyl‐ ( 3 )) at the 10‐position of anthracene and poly(ethylene oxide) with the number of repeating units of 7 connected with biphenyl as coil segments were synthesized. The molecular structures were characterized by ¹H NMR and MALDI‐TOF mass spectroscopy. The self‐assembling behavior of new type of molecules 1–3 was investigated by means of DSC, POM, and SAXS at the bulk state. These molecules with a n‐shaped rod building block segment self‐assemble into supramolecular structures through the combination of π–π stacking of rigid rod building blocks and microphase separation of the rod and coil blocks. SAXS studies reveal that molecules 1 and 2 show hexagonal columnar and rectangular columnar structures in the liquid crystalline phase, respectively; meanwhile, molecules 1–3 self‐organize into lamellar structures in the crystalline state. In addition, self‐assembling studies of molecules 1–3 by DLS and TEM indicated that these molecules self‐assemble into elongated nanofibers in aqueous medium. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1415–1422, 2010