With the aim of enhancing the field‐effect mobility of self‐assembled regioregular poly(3‐hexylthiophene), P3HT, by promoting two‐dimensional molecular ordering, the organization of the P3HT in precursor solutions is transformed from random‐coil conformation to ordered aggregates by adding small amounts of the non‐solvent acetonitrile to the solutions prior to film formation. The ordering of the precursor in the solutions significantly increases the crystallinity of the P3HT thin films. It is found that with the appropriate acetonitrile concentration in the precursor solution, the resulting P3HT nanocrystals adopt a highly ordered molecular structure with a field‐effect mobility dramatically improved by a factor of approximately 20 depending on the P3HT concentration. This improvement is due to the change in the P3HT organization in the precursor solution from random‐coil conformation to an ordered aggregate structure as a result of the addition of acetonitrile. In the good solvent chloroform, the P3HT molecules are molecularly dissolved and adopt a random‐coil conformation, whereas upon the addition of acetonitrile, which is a non‐solvent for aromatic backbones and alkyl side chains, 1D or 2D aggregation of the P3HT molecules occurs depending on the P3HT concentration. This state minimizes the unfavorable interactions between the poorly soluble P3HT and the acetonitrile solvent, and maximizes the favorable π–π stacking interactions in the precursor solution, which improves the molecular ordering of the resulting P3HT thin film and enhances the field‐effect mobility without post‐treatment.

Hydrogen-bonding-directed layer-by-layer assembled films, based on polystyrene-block-poly(acrylic acid) (PS-b-PAA) block copolymer micelles and poly(4-vinylpyridine) (P4VP), were successfully fabricated in methanol. Varying the PAA content in the PS-b-PAA micelles afforded control over the film growth properties, especially the multilayer film thickness. Interestingly, antireflection films with refractive indices that could be tuned between 1.58 and 1.28 were obtained by treatment with an aqueous HCl solution (pH 2.27), and the transmittance obtained was as high as 98.4%. In acid solution, the pyridine group was protonated, destroying the hydrogen bonding between P4VP and PAA. A concomitant pH-induced polymer reorganization in the multilayers resulted in a porous honeycomb-like texture on the substrate.

For environmental conservation, post-consumer polyethylene terephthalate (PET) bottles are recycled using methods ranging from mechanical recycling to various chemical recycling processes. In this study, the characterization of recycled PETs and PET–nylon6 blend knitted fabrics, and virgin PET knitted fabric, was carried out with the aim of broadening the application of recycled PET fabrics. The tensile strength values of mechanically and chemically recycled PET knitted fabrics were similar to those of virgin PET knitted fabric. The elongation of recycled PET–nylon6 blend knitted fabric was the best. Both virgin and recycled PET knitted fabrics had excellent pilling resistance. Based on the drape ratio, the recycled PET–nylon6 blend knitted fabric was more flexible than other samples. The warm/cool feeling ( Qmax), compressional and surface properties were measured using the Kawabata evaluation system for fabrics (KES-FB system). The compressional properties of mechanically recycled PET knitted fabric were similar to those of virgin PET knitted fabric. The recycled PET–nylon6 blend knitted fabric showed the smoothest appearance and coolest feeling among the four samples. Moisture regain and moisture permeability were the best in recycled PET–nylon6 blend knitted fabric. However, the wickability of mechanically recycled PET knitted fabric was better than other recycled PET knitted fabrics.

Chemically recycled polyester fibers consisting of a core and sheath layer were used to produce nonwoven fabrics for ecofriendly automotive interiors. The density and thermal shrinkage of the recycled polyester nonwoven fabrics were higher than in virgin polyester nonwoven fabrics, irrespective of the heat-setting temperature and time, but the air permeability was lower. The wicking property of the recycled polyester nonwoven fabrics decreased significantly above 180℃. The tensile stress and modulus of the recycled polyester nonwoven fabrics increased gradually with increasing heat-setting temperature. However, the strain at maximum stress of the recycled polyester nonwoven fabrics decreased rapidly. The abrasion strength of the recycled polyester nonwoven fabrics improved above a heat-setting temperature of 200℃. The impact strength of the recycled polyester nonwoven fabrics was higher than that of virgin polyester nonwoven fabrics. As the heat-setting temperatures used for the nonwoven fabrics were higher than the melting temperature of chemically recycled and virgin polyester fibers, thermal bonding occurred between fibers. The lightness of the recycled polyester nonwoven fabrics decreased with increased heat-setting temperature and time. The recycled polyester nonwoven fabrics also showed slight yellowing. The thermal bonding between the fibers in the recycled polyester nonwoven fabrics was generated at a lower heat-setting temperature than for virgin polyester nonwoven fabrics, and therefore it is considered that under more relaxed heat treatment conditions, the recycled polyester nonwoven fabrics would show a performance similar to that of the virgin ones.

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