Stimuli-responsive colorimetric polydiacetylene sensor in polar organic solvent

Polydiacetylene (PDA) has been actively employed as sensing vehicles owing to its unique colorimetric feature upon environmental stimulation. Here, blue phase PDA has been constructed by topological polymerization of commercial diacetylene acid (DA) noncovalently modified by guest amines. Specifically, PDA including 1-naphthylmethylamine noncovalently bonded on both sides exhibits long-term stability in polar organic solvents. The stability of PDA depended upon both the structures of the DA and the guest molecule, underscoring a stabilizing mechanism dominated by noncovalent bonding and strong π–π interaction. Accordingly, the blue phase PDA shows a colorimetric response from blue to red upon exposure to stimuli influencing noncovalent bonding and π–π interaction, such as elevated temperature, the existence of acid or alkali at concentrations as low as 50 ppm. Therefore, the PDA developed in this study has the potential of serving as a colorimetric sensor for detecting subtle environment changes and especially for measuring the quality of polar organic solvents recovered from industrial effluent.     

Topochemical polymerisation of a diacetylene: Studies of lattice parameters and thermal expansion coefficients

The solid-state polymerisation of the disubstituted diacetylene, 2,4-hexadiynylene bis(p-toluene sulphonate). has been studied by x-ray diffraction in the temperature range 223 to 295 K. The variation in lattice parameters is shown to be similar to that reported in previous less extensive studies. This data is used to determine the behaviour of the thermal expansion coefficients as a function of polymer content. The relevance of these results to the question of polymer chain lengths at low conversion is discussed.     

Flexible patch‐type hydrochromic polydiacetylene sensor for human sweat pore mapping

Owing to their stimulus‐responsive colorimetric property, polydiacetylenes (PDAs) have been extensively investigated in the context of sensor applications. Incorporation of PDAs in matrix polymers can be utilized to add additional advantageous features into these sensors, like processability, mechanical flexibility, and mass production capability. In the current investigation, a new type of hydrochromic PDA sensor, which consists of a polydiacetylene‐polyethylene oxide (PDA‐PEO) composite film, was developed. The results of the study demonstrate that the hydrochromic film, which displays a blue‐to‐red color transition upon hydration, can be used to map human sweat secreting pores. The hygroscopic PEO component of the system enables local sweat to penetrate into the sensor film. The highly π‐conjugated, imidazolium group containing PDA in the system functions as the hydrochromic material, which undergoes a blue‐to‐red transition and a corresponding fluorescence turn‐on in response to contact with a nanoliter of sweat. In response to deposition of a fingerprint, water arising from individual sweat secreting pores promotes a change that leads to formation of a discrete fluorescence microdot pattern. The most important feature of the new sensor film is mechanical flexibility that gives it with the ability to be utilized to map sweat pores located on highly curved skin surfaces, such as those found on palms, soles, backs, and faces. Accordingly, this attribute offers critical advantages in cosmetics and biomedical applications because it enables recognition of active and inactive sweat pores on curved skin surfaces where rigid or paper‐type sweat pore sensors are ineffective. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44419.     

尿烷取代聚二炔反饱和吸收光限幅特性的研究

聚合炔（ＰＤＡｓ）材料有较大的非线性光学效应，在全光设备中有较大的在应用本文分别研究了尿烷取聚二乙炔的增强吸收和粗糙界面的光限幅特性，并分析了共限幅机理，发现粗糙界面光限幅比增强吸收光限幅有更好的光限幅特征。     

聚丁二炔气敏传感应用的研究现状及展望

分析了聚丁二炔作为气敏传感材料的机理,总结了不同结构聚丁二炔衍生物作为气敏传感材料的研究现状。本文以聚氨酯、石墨烯、二硫化钼、纤维素纳米晶等增强材料为例,阐述了聚丁二炔复合材料的气敏增强原理、优点及存在的问题,介绍了如食物腐败的检测、便携腕式传感器等新型传感场合的应用研究。目前,聚丁二炔作为气敏传感材料还处于起步阶段,光学转变机理不明确、侧基改性工艺烦琐、官能团种类有限、易受环境影响失效等问题都亟待解决;未来应拓宽对增强材料的选择,调控复合材料的结构以实现对待测气体的高选择性和高灵敏度响应,更要发挥聚丁二炔复合材料成型工艺简单、与环境相容性好的优点,制备更具功能化的气敏材料。     

A Microneedle Technology for Sampling and Sensing Bacteria in the Food Supply Chain

Food quality monitoring, particularly, the detection of bacterial pathogens and spoilage throughout the food supply chain, is critical to ensure global food safety and minimize food loss. Incorporating sensors into packaging is promising, but it is challenging to achieve the required sampling volume while using food-safe sensor materials. Here, by leveraging water-based processing of silk fibroin, a platform for the detection of pathogenic bacteria in food is realized using a porous silk microneedle array; the microneedle array samples fluid from the interior of the food by capillary action, presenting the fluid to polydiacetylene-based bioinks printed on the backside of the array. Through the colorimetric response of bioink patterns, Escherichia coli contamination in fish fillets is identified within 16 h of needle injection. This response is distinct from spoilage measured via the increase in sample pH. It is also shown that the microneedles can pierce commercial food packaging, and subsequently sample fluid and present it to the sensor, enabling the adaptation of the technology downstream in food supply chains such as in stores or at home. This study highlights that regenerated structural biopolymers can serve as safe materials for food contact and sensing with robust mechanical properties and tailored chemistry.     

三阶非线性光学共轭聚合物

论述了近年来共轭聚合物三阶非线性光学研究的主要进展,包括聚二乙炔,导电聚合物（如聚乙炔,聚噻吩类）以及刚性芳杂环梯形聚合物等,并展望了它们潜在的应用前景。     

Large friction anisotropy of a polydiacetylene monolayer

Friction force microscopy measurements of a polydiacetylene monolayer film reveal a 300% friction anisotropy that is correlated with the film structure. The film consists of a monolayer of the red form of N‐(2‐ethanol)‐10,12‐pentacosadiynamide, prepared on a Langmuir trough and deposited on a mica substrate. As confirmed by atomic force microscopy and fluorescence microscopy, the monolayer consists of domains of linearly oriented conjugated backbones with pendant hydrocarbon side chains above and below the backbones. Maximum friction occurs when the sliding direction is perpendicular to the backbones. We propose that this effect is due to anisotropic film stiffness, which is a result of anisotropic side chain packing and/or anisotropic stiffness of the backbone itself. Friction anisotropy is therefore a sensitive, optically‐independent indicator of polymer backbone direction and monolayer structural properties. This revised version was published online in September 2006 with corrections to the Cover Date.     

Realization of reversible thermochromic polydiacetylene through silica nanoparticle surface modification

The novel functionalized poly(silanization alcoholamine diacetylene)/silica nanoparticles (poly(SiDGADA)/SiO₂ nanoparticles) have been achieved for reversible thermochromism. The silanized alcoholamine diacetylenic monomer (SiDGADA) is condensed with the hydroxyl group of SiO₂ nanoparticle via hydrolysis of the SiDGADA siloxy group, followed by fixation after being polymerized upon UV light stimulation. The maximum thermal decomposition rate of the SiDGADA/SiO₂ nanoparticles is 0.65%/°C at 460°C, while the maximum thermal decomposition rate of the SiDGADA is 1.92%/°C at 400°C. Poly(SiDGADA)/SiO₂ nanoparticles appears a blue phase after photo polymerization and exhibits a distinctive red phase at the discoloration temperature of 65°C, which is 5°C higher than that of the pure poly(SiDGADA). It shows excellent reversible thermochromic properties, undergoing stable reciprocal blue-to-red conversion from 25 to 65°C, and returning to bluish violet after cooling. The extension of the SiDGADA alkyl chain length with formation of the covalent bond, to promote the interaction between the alkyl chains of polydiacetylene (PDA). This work provides a strategy to effectively improve the reversibility of thermochromic PDA.