Poly(Pyridinium Salt)s Containing 2,7-Diamino-9,9'-Dioctylfluorene Moieties with Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline and Light-Emitting Properties.

A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (1H), and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (Mns) between 96.5 and 107.8 kg/mol and polydispersity index (PDI) in the range of 1.12-1.88. They exhibited fully-grown lyotropic phases in polar protic and aprotic solvents at different critical concentrations. Small-angle X-ray scattering for one polymer example indicates lyotropic structure formation for 60-80% solvent fraction. A lyotropic smectic phase contains 10 nm polymer platelets connected by tie molecules. The structure also incorporates a square packing motif within platelets. Thermal properties of polymers were affected by the size of counterions as determined by differential scanning calorimetry and thermogravimetric analysis measurements. Their ultraviolet-visible (UV-Vis) absorption spectra in different organic solvents were essentially identical, indicating that the closely spaced π-π* transitions occurred in their conjugated polymer structures. In contrast, the emission spectra of polymers exhibited a positive solvatochromism on changing the polarity of solvents. They emitted green lights in both polar and nonpolar organic solvents and showed blue light in the film-states, but their λem peaks were dependent on the size of the counterions. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0-90%), and their λem peaks were blue shifted.

Phosphine Oxide Containing Poly(pyridinium salt)s as Fire Retardant Materials.

Six new rugged, high-temperature tolerant phosphine oxide-containing poly(4,4'-(p-phenylene)-bis(2,6-diphenylpyridinium)) polymers P-1, P-2, P-3, P-4, P-5, and P-6 are synthesized, characterized, and evaluated. Synthesis results in high yield and purity, as confirmed by elemental, proton (1H), and carbon 13 (13C) nuclear magnetic resonance (NMR) spectra analyses. High glass transition temperatures (Tg > 230 °C) and high char yields (>50% at 700 °C) are determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. These new ionic polymers exhibit excellent processability, thin-film forming, high-temperature resistance, fire-resistance and retardation, coating, adhesion, mechanical and tensile strength, and n-type (electron transport) properties. The incorporation of phosphine oxide and bis(phenylpyridinium) moieties in the polymer backbones leads to high glass transition temperatures and excellent fire retardant properties, as determined by microcalorimetry measurements. The use of organic counterions allows these ionic polymers to be easily processable from several common organic solvents. A large variety of these polymers can be synthesized by utilizing structural variants of the bispyrylium salt, phosphine oxide containing diamine, and the counterion in a combinatorial fashion. These results make them very attractive for a number of applications, including as coating and structural component materials for automobiles, aircrafts, power and propulsion systems, firefighter garments, printed circuit boards, cabinets and housings for electronic and electrical components, construction materials, mattresses, carpets, upholstery and furniture, and paper-thin coatings for protecting important paper documents.

Conformation-specific spectroscopy and populations of diastereomers of a model monolignol derivative: chiral effects in a triol chain.

Single-conformation spectroscopy of two diastereomers of 1-(4-hydroxy-3-methoxyphenyl)propane-1,2,3-triol (HMPPT) has been carried out under isolated, jet-cooled conditions. HMPPT is a close analog of coniferyl alcohol, one of the three monomers that make up lignin, the aromatic biopolymer that gives structural integrity to plants. In HMPPT, the double bond of coniferyl alcohol has been oxidized to produce an alkyl triol chain with chiral centers at C(α) and C(ß), thereby incorporating key aspects of the ß-O-4 linkage between monomer subunits that occurs commonly in lignin. Both (R,S)- and (R,R)-HMPPT diastereomers have been synthesized in pure form for study. Resonant two-photon ionization (R2PI), UV hole-burning (UVHB)/IR-UV hole-burning (IR-UV HB), and resonant ion-dip infrared (RIDIR) spectroscopy have been carried out, providing single-conformation UV spectra in the S(0)-S(1) region (35200-35800 cm(-1)) and IR spectra in the hydride stretch region. Five conformers of (R,S)- and four conformers of (R,R)-HMPPT are observed and characterized, leading to assignments for all nine conformers. Spectroscopic signatures for α-ß-γ, γ-ß-α, and α-γ-ß-π chains and two cyclic forms [(αßγ) and (αγß)] of the glycerol side chain are determined. Infrared ion-gain (IRIG) spectroscopy is used to determine fractional abundances for the (R,S) diastereomer and constrain the populations present in (R,R). The two diastereomers have very different conformational preferences. More than 95% of the population of (R,R) configures the glycerol side chain in a γ-ß-α triol chain, while in (R,S)-HMPPT, 51% of the population is in α-ß-γ chains that point in the opposite direction, with an additional 21% of the population in H-bonded cycles. The experimental results are compared with calculations to provide a consistent explanation of the diastereomer-specific effects observed.