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Wearable thermoelectric generators are a promising energy source for powering activity trackers and portable health monitors. However, known iterations of wearable generators have large form factors, contain expensive or toxic materials with low elemental abundance, and quickly reach thermal equilibrium with a human body, meaning that thermoelectric power can only be generated over a short period of wear. Here, an all‐fabric thermopile is created by vapor printing persistentlyp‐doped poly(3,4‐ethylenedioxythiophene) (PEDOT‐Cl) onto commercial cotton and this thermopile is integrated into a specially designed, wearable band that generates thermovoltages >20 mV when worn on the hand. It is shown that the reactive vapor coating process creates mechanically rugged fabric thermopiles that yield notably high thermoelectric power factors at low temperature differentials, as compared to solution‐processed counterparts. Further, best practices for naturally integrating thermopiles into garments are described, which allow for significant temperature gradients to be maintained across the thermopile despite continuous wear.

 

Green-processed conjugated materials can reduce the cost of optoelectronic devices and simultaneously minimize their ecological footprint. Here, we use both solution and vapor phase chemistry to oxidatively polymerize the natural hydrocarbon dye, guaiazulene, yielding the more functional material poly(guaiazulene). We chemically characterize oligomers of poly(guaiazulene) using nuclear magnetic resonance spectroscopy, gel-permeation chromatography, laser-desorption ionization mass spectroscopy, and ultraviolet-visible absorption spectroscopy. The optical properties of poly(guaiazulene) oligomers are studied via electronic structure calculations and are contrasted to those of standard poly(azulene). We show that poly(guaiazulene) films synthesized from the vapor phase exhibit enhanced optical properties compared to counterparts synthesized in solution. Collectively, this work outlines a green reaction process that consists of a single step and uses earth-abundant reagents to yield a hitherto unreported polymer for optoelectronic applications. 

Climate change is leading to increased concentrations of ground-level ozone in farms and orchards. Persistent ozone exposure causes irreversible oxidative damage to plants and reduces crop yield, threatening food supply chains. Here, we show that vapor-deposited conducting polymer tattoos on plant leaves can be used to perform on-site impedance analysis, which accurately reveals ozone damage, even at low exposure levels. Oxidative damage produces a unique change in the high-frequency (>10 4 Hz) impedance and phase signals of leaves, which is not replicated by other abiotic stressors, such as drought. The polymer tattoos are resilient against ozone-induced chemical degradation and persist on the leaves of fruiting plants, thus allowing for frequent and long-term monitoring of cellular ozone damage in economically important crops, such as grapes and apples. 

Reactive vapor deposition (RVD) is a nascent, single-step processing method for forming electronic polymer films on unconventional substrates and is increasingly important for creating flexible and wearable electronics. RVD can be interpreted as a solvent-free synthetic technique, where multiple reagents converge in the vapor phase to effect a polymerization reaction. Here, we review reactive vapor deposition of conjugated polymers from a synthetic perspective, starting by establishing its roots in inorganic chemical vapor deposition, tracking its evolution over the recent decade, discussing state-of-the-art monomer and polymer scope, and concluding with an examination of shortcomings where increased attention from the synthetic community would yield impactful advances. 

Commercial, untreated cotton fabrics have been directly silver coated using one-step electroless deposition and, subsequently, conformally encapsulated with a thin layer of poly(perfluorodecylacrylate) (PFDA) using initiated chemical vapor deposition (iCVD). The surface of these PFDA encapsulated fabrics are notably water-repellent while still displaying a surface resistance as low as 0.2 Ω cm −1 , making them suitable for incorporation into launderable wearable electronics. X-ray photoelectron spectroscopy confirms that the PFDA encapsulation prevents oxidation of the silver coating, whereas unencapsulated samples display detrimental silver oxidation after a month of air exposure. The wash stability of PFDA-encapsulated, silver-coated cotton is evaluated using accelerated laundering conditions, following established AATCC protocols, and the samples are observed to withstand up to twenty home laundering cycles without notable mechanical degradation of the vapor-deposited PFDA encapsulation. As a proof-of-concept, PFDA-Ag cotton is employed as a top and bottom electrode in a layered, all-fabric triboelectric generator that produces voltage outputs as high as 25 V with small touch actions, such as tapping. 

A facile, solvent-minimized approach to functionalize commercial raw fabrics is described. Reactive vapor deposition of conjugated polymers followed by post-deposition functionalization transforms common, off-the-shelf textiles into distinctly hydrophobic or superhydrophilic materials. The fabric coatings created by reactive vapor deposition are especially resistant to mechanical and solvent washing, as compared to coatings applied by conventional, solution-phase silane chemistries. Janus fabrics with dissimilar wettability on each face are also easily created using a simple, three-step vapor coating process, which cannot be replicated using conventional solution phase functionalization strategies. Hydrophobic fabrics created using reactive vapor deposition and post-deposition functionalization are effective, reusable, large-volume oil–water separators, either under gravity filtration or as immersible absorbants.