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Amphiphilic diblock copolymers were synthesized based on poly(2-ethyl-2-oxazoline) (PEtOz) as a hydrophilic block and aliphatic polyesters such as poly(l-lactide) (PLA) or poly(ε-caprolactone) (PCL) as a hydrophobic block. Their micellar characteristics in an aqueous phase were investigated by using dynamic light scattering and fluorescence techniques. The block copolymers formed micelles in the aqueous phase with critical micelle concentrations (cmcs) in the range of 1.0−8.1 mg/L. The cmc values become lower upon increasing the length of the hydrophobic block. The mean diameters of the micelles were in the range of 108−192 nm, with a narrow distribution. In general, the micelle size increased as the hydrophobic PLA or PCL block became larger. The partition equilibrium constants, K v, of pyrene in the micellar solutions of the block copolymers were from 1.79 × 105 to 5.88 × 105. For each block copolymer system of PEtOz−PLA or PEtOz−PCL, the K v value increased as the length of the hydrophobic block increased. The steady-state fluorescence anisotropy values (r) of 1,6-diphenyl-1,3,5-hexatriene (DPH) were 0.265−0.284 in PEtOz−PLA solution and 0.189−0.196 in PEtOz−PCL solution. The anisotropy values of PEtOz−PLAs were higher than those of PEtOz−PCLs. The anisotropy values were independent of the length of the hydrophobic block when the chemical structures of the hydrophobic blocks were identical. The micelles underwent hydrogen bonding at pH <3.5 with poly(acrylic acid), which produced polymer complex precipitates that could be reversibly dispersed as micelles at pH >3.8.

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Single-walled carbon nanotubes (SWCNTs) dispersed with Nafion in a solvent mixture containing de-ionized water and 1-propanol (bisolvent) were sprayed on a poly(ethylene terephthalate) substrate to fabricate flexible transparent conducting films (TCFs). Different SWCNT-to-Nafion ratios were used to optimize the film performance of transparence and sheet resistance. The TCFs were then immersed in nitric acid. These steps resulted in p-type doping due to the presence of Nafion in the SWCNT network and de-doping (removal of doping effect) by the acid treatment. X-Ray photoelectron and Raman spectroscopy confirmed that the de-doping effect occurred with the partial removal of Nafion from the nanotube surface by the nitric acid treatment, which improved the film conductivity by a factor of $4 with negligible change in transmittance.

An amphiphilic polyphosphazene diblock copolymer (MEEP-Ph/MEEP) based on [Nd P(OCH 2CH2OCH2CH2OCH3)2]n (MEEP) as a hydrophilic block and [NdPPh(OCH2CH2OCH2CH2OCH3)]m (Ph/MEEP) as a hydrophobic block was synthesized via the controlled cationic block copolymerization of phosphoranimine. The molecular weight of the block copolymer was estimated by GPC to be 3300. The molar composition ratio of repeating unit in the MEEP block to those in the Ph/MEEP block was 0.5. The micellar characterization of MEEP-Ph/MEEP in an aqueous phase was carried out by using fluorescence techniques, dynamic light scattering, and TEM. The block copolymer formed micelles with a critical micelle concentration (cmc) of 80 mg/L. The hydrodynamic radius (R h) of micelles, measured by dynamic light scattering, was 120 nm at 25 °C with a narrow distribution. The TEM image showed micelles with a spherical shape. Intermicellar aggregation was induced in the micellar solution of the block copolymer above 57 °C. The partition equilibrium constant, Kv, of pyrene in the micellar solution of the block copolymer was 7.0 × 10 3 . The steady-state fluorescence anisotropy value (r) of 1,6-diphenyl-1,3,5hexatriene (DPH) was 0.237. The fluorescence lifetime value for DPH in the block copolymer solution showed that the core region of the micelles consisted of two regions with different hydrophobicities.

A new class of amphiphilic linear-dendritic diblock copolymers based on hydrophilic linear PEO and hydrophobic dendritic carbosilane were synthesized using a divergent approach at the allyl end group of the allyl-terminated PEO. The amphiphilic nature of these block copolymers was highly dependent on the size of the hydrophobic dendritic block. The block copolymer with the dendritic moiety of a third generation could not be dispersed in water. The block copolymers with the first (PEO-Si-1G) and, the second (PEO-Si-2G) generation of dendritic carbosilane blocks form micelles in an aqueous phase. The critical micelle concentrations of PEO-Si-1G and PEO-Si-2G, determined by a fluorescence technique, were 82.6 and 2.3 mg/L, respectively. The mean diameters of the micelles of PEO-Si-1G and PEO-Si-2G, measured by dynamic light scattering, were 120 and 170 nm. The partition equilibrium constants, Kv, of pyrene in the micellar solution increased by increasing the size of the dendritic block, e.g., 9.13 × 10 3 for PEO-Si-1G and 1.75 × 10 5 for PEO-Si-2G. The steady-state fluorescence anisotropy values (r) of 1,6diphenyl-1,3,5-hexatriene (DPH) were 0.08 for PEO-Si-1G and 0.10 for PEO-Si-2G. The r values were lower than the linear polymeric amphiphiles, suggesting that the microviscosity of the dendritic micellar core is lower than those of other polymeric micelles.

The micellar characteristics of the amphiphilic diblock copolymers based on a hydrophobic polyphosphazene (PN) and hydrophilic poly(ethylene oxide) (PEO) were investigated by using fluorescence techniques, dynamic light scattering, and transmission electron microscopy. The two diblock copolymers with different ratios of the length of block components form spherical micellar aggregates in an aqueous phase. The critical micelle concentrations of PN-PEO 1 and PN-PEO 2, determined by a fluorescence technique, were 12.4 and 5.2 mg/L, respectively. The mean diameters of the micelles of PN-PEO 1 and PN-PEO 2, measured by dynamic light scattering, were 100 and 120 nm. The steady-state fluorescence anisotropy values (r) of 1,6-diphenyl-1,3,5-hexatriene (DPH) were 0.103 for PN-PEO 1 and 0.108 for PN-PEO 2. The low anisotropy values for PEO-PN compared to those for other polymeric amphiphiles may be due to the intrinsic flexibility of the trifluoroethoxy-substituted polyphosphazene block, which would allow enhanced rotational diffusion of the probe.

Amphiphilic diblock copolymers with varying compositions of hydrophilic poly[bis(methoxyethoxyethoxy)phosphazene] and hydrophobic polystyrene were synthesized via the living, cationic polymerization of Cl3PNSiMe3, using a polystyrenyl−phosphoranimine as a macroterminator. The self-association behavior of the block copolymers in aqueous media was investigated using fluorescence spectroscopy, transmission electron microscopy, and dynamic light scattering. The critical micelle concentrations of PS−MEEP block copolymers with molar block ratios of 1:0.37, 1:0.58, 1:0.70, and 1:0.86 were determined to be 1.8, 2.3, 10.0, and 13.6 mg/L, respectively. The mean diameters of micelles of these block copolymers were measured as 167, 168, 179, and 173 nm through dynamic light scattering. The equilibrium constants of pyrene in these micelles ranged from 5.75 × 105 to 7.31 × 104.