Preparation of Latex Film with Macropores and Their Applications in Pigment Dyeing

Aiming at improving the permeability of the pigment dyed fabrics,two kinds of hydrophilic polymers(polyvinyl pyrrolidone(PVP),and polyethylene glycol(PEG)were fed into the styrene-butyl acrylate(St-BuA)copolymer latex binder respectively to prepare films with macropores.The effects of the post-added polymers on the latex film formation process and film structures were studied and the performance of the dyed fabrics was evaluated.It was found that the drying process could still be divided into three stages even after the addition of PVP and PEG.And the water evaporation rate during the first and last stage remained the same as usual.However,after the addition of PVP,the onset of the second stage was delayed to high volume fraction,and PVP formed into spherical dispersion phase with 300 nm in diameter.It provided a great deal of interface between the latex polymer and the PVP phase,which led to an increase in the water evaporation rate during the second stage.A different case was found after the feeding of PEG.Firstly,the first stage ended at low volume fraction and a decreased evaporation rate was observed in the second stage.Secondly,the PEG dispersion appeared as finger-like structure in the transmission electron microscopy(TEM)images with 9μm in length.After rinsing,pores were found only in the films formerly containing PVP or PEG,and the shapes and the sizes were closely correlated with the initial morphologies of the PVP or PEG domains.However,the shade of color,the abrasion fastness,and the permeability of the dyed fabric were independent of the type of the post-added hydrophilic polymer.

Effect of Polyvinylpyrrolidone on the Morphologies of Latex Films and Air Permeability of the Latex Finished Fabrics

Low air permeability is a common problem happening to the coating finished and pigment dyed fabrics.To tackle the problem,styrene and butyl acrylate copolymer latex was prepared and used as substitute for the binder.Then,polyvinylpyrrolidone(PVP)was fed into the latex.It was expected that pores could form in the resulting latex film after being rinsed.The morphologies of the latex films were analysized by scanning electric microscope(SEM).It was found that the continuity of the latex films decreased greatly because of the addition of PVP,leading to the loss of the stress at break of the films.After rinsing with methanol aqueous solution,PVP was easily leached off and(macro)void was formed in the latex films.The size of the void decreased with the increase of the PVP concentration.Then,the latex with and without PVP was used to finish the cotton fabrics and engaged as binder in pigment dyeing.After PVP was rinsed out,the air permeability of the fabrics improved greatly,which recovered to that of the unfinished one.In the meantime,the color fastness to rubbing was little affected.So,the method of PVP addition could be termed as an efficient way to improve the air permeability in coating and dyeing industry.

The Waterborne Polyurethane Binder from Alkali Lignin

Waterborne polyurethane(WPU) binder was synthesized by refined alkali lignin(RAL) with 4,4′-diphenylmethane diisocyanate(MDI).Fourier transform infrared spectroscopy(FTIR) was used to clarify the group change of raw materials-alkali lignin(AL),MDI,and product WPU,and laser particle analyzer was used to analyze the particle size of WPU.The results were as follows: AL could react with MDI to produce WPU binder.The reaction extent,the dispersion,and dispersion stability of WPU were influenced by/ratio.The WPU synthesized by AL,polyethylene glycol(PEG) and MDI was used as a binder in pigment dyeing process.In this process,the influence factors,such as binders made by different ratio of materials,the concentration of binder,curing temperature,and curing time were analyzed respectively.

Fluorescent Organohydrogel with Thermal-Induced Color Change for Anti-counterfeiting

Smart fluorescent patterns enable dynamic color variation under external stimuli,showing a much higher security level in the field of anti-counterfeiting.However,there is still lacking of a simple and convenient way to achieve dynamic fluorescence changes.Herein,a fluorescent organohydrogel made up of a poly(N,/N-dimethylacrylamide-co-isopropylacrylamide)(p(DMA-NIPAM))hydrogel network and a polyflauryl methacrylate)(PLMA)organogel network was fabricated via a two-step interpenetrating technique.The former network bears naphthalimide moieties(DEAN,green fluorescent monomer)and the later contains 6-acrylamidopicolinic acid(6APA,fluorescent ligand),leading to emitting green fluorescence.When Eu^(3+) was introduced and coordinated with 6APA,the organohydrogel displays red fluorescence,which can further emit yellow after applying thermal stimulus.Furthermore,by adjusting the proportion of comonomers,various organohydrogels can be obtained,which can be programmed and act as an effective platform for the encryption and decryption of secret information.

The colorful chemistry of nanoscale zero-valent iron(nZVI)

Nanoscale zero-valent iron （nZVI） possesses unique chemistry and capability for the separation and transformation of a growing number of environmental contaminants. A nZVI particle consists of two nanoscale components, an iron （oxyhydr）oxides shell and a metallic iron core. This classical ＂core-shell＂ structure offers nZVI with unique and multifaceted reactivity of sorption, complexation, reduction and precipita- tion due to its strong small particle size for engineering deployment, large surface area, abundant reactive sites and electron-donating capacity for enhanced chemical activity. For over two decades, research has been steadily expanding our understanding on the reaction mechanisms and engineering performance of nZVI for soil and groundwater remediation, and more recently for wastewater treatment.

Advances in Polymethine Dyes for Near-Infrared Organic Photodiodes

Near-infrared organic photodiodes (NIR OPDs) have tremendous potential in industrial, military, and scientific applications, due to their unique features of lightweight, low toxicity, high structural flexibility, cooling-system-free, etc. However, the overall performance of currently available NIR OPDs still lags behind the commercial inorganic photodetectors, ascribed to the critical challenge of realizing organic semiconductors with sufficiently low optical bandgap and excellent optoelectronic properties simultaneously. Among various types of NIR-absorbing organic semiconductors, polymethine dyes not only possess advantages of simple synthesis and structural diversity, but also show fascinating optical and aggregation features in the solid state, making them attractive material candidates for NIR OPDs. In this review, after a brief introduction of NIR OPDs and polymethine dyes, we comprehensively summarize the advances of polymethine dyes for broadband and narrowband NIR OPDs, and further introduce their applications in all-organic optical upconversion devices and photoplethysmography sensors. In particular, the relationship between the chemical structure and the aggregation behaviors of polymethine dyes and the device performance is carefully discussed, providing some important molecular insights for developing high performance NIR OPDs.

Fine Tuning of the Electronic Properties of Novel BTPE Using Oligosilanyl Linkages and Their Application in Rapid High-Resolution Visualization of Latent Fingerprints

Structural modifications throughπ-interactions usually result in redshifts in luminescence and,as a consequence,the loss of the natural color of the chromophore.Besides,employing Si-Siσ-bridging to manipulate the electronic properties of organic materials has remained largely unexplored.Herein,we report a series of novel bis-tetraphenylethenes(BTPEs)with oligosilanyl linkages,termed BTPE-Sin molecules,used to manipulate the photophysical properties of luminogens subtly throughσ–πconjugation.These oligosilanyl-bridged molecules were thermally,highly stable,and exhibited enhanced aggregation-induced emissions,as well as luminescence efficiencies while retaining most of their original color.Our current BTPEs fabrications have easy-to-operate,fast,and high-resolution identification properties toward LFPs.Also,they are highly specific to individuals,and hence,vital in forensic investigations.We achieved these features through the introduction of oligosilanyl chains that increased the lipophilicity of the significantly.This work offers a universal and straightforward approach for the generation of highly emissive organic materials and enables fine-tuning of their electronic properties for multifunctional applications.