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A signature of photo-mediated controlled polymerizations is the ability to modulate the rate of polymerization by turning the light source 'on' and 'off.' However, in many reported systems, growth can be reproducibly observed during dark periods. In this study, emerging photo-mediated controlled radical polymerizations are evaluated with in situ 1H NMR monitoring to assess their behavior in the dark. Interestingly, it is observed that Cu-mediated systems undergo long-lived, linear growth during dark periods in organic media.

Three‐dimensional (3D) printed multimaterials have quickly grown in interest as researchers aim to mimic the material chemistry and geometric complexity of natural materials. While some exceptional multimaterial 3D printing systems have been developed, there is still a shortfall in the scope and production of these materials. More recently, the introduction of xolography as a single‐step, auxiliary‐free additive manufacturing approach has enabled rapid production of materials with geometries inaccessible via other additive manufacturing techniques. However, previous systems required resins with high transparency for effective material formation, and multimaterial formation has not been demonstrated. In this work, reversible deactivation radical polymerization is used and resin composition, viscosity, and processing parameters are explored to develop new resins capable of application to visible light‐mediated xolography. After optimization, non‐transparent resins containing thiocarbonylthio species are applied to xolography to manufacture geometrically complex, auxiliary‐free materials. The resulting 3D printed polymer network materials can be functionalized via the embedded thiocarbonylthio moieties to impart new functionality to the printed materials. Finally, the unique 3D printing capabilities of xolography are demonstrated to manufacture multimaterials featuring chemically disparate domains with high 3D‐spatial control. This two‐step overprinting approach is operationally simple and provides a new avenue for manufacturing polymeric multimaterials via 3D printing. [ABSTRACT FROM AUTHOR]

We present the use of an oxygen tolerant controlled radical polymerization (photoinduced electron/energy transfer-reversible addition fragmentation chain transfer polymerization, PET-RAFT) as a simple method for preparing controlled radical polymers in an undergraduate laboratory. Unlike conventional techniques, PET-RAFT polymerizations require no deoxygenation, heating, or special equipment. This removes hazards and complexity from the experimental setup, as well as sources of error and variability in the polymers produced. In this program, students used PET-RAFT to synthesize poly(N-isopropylacrylamide) coated gold nanoparticles and studied the effect of the polymer on the size, optical properties, and aggregation state of the nanoparticles in response to temperature. In parallel, students used PET-RAFT to study the chemistry of radical copolymerization by measuring the reactivity ratios of a range of vinylic monomers. Both experiments would be very difficult to perform in an undergraduate laboratory by conventional controlled radical polymerization techniques. The PET-RAFT technique we present can be used to prepare well-defined polymers easily for any number of applications beyond this, particularly in materials, biology, engineering, and physics laboratories that are not set up for complicated polymer synthesis.

Traditionally, combining carbon and ceramic materials has been challenging due to their different chemical and physical properties. Despite the development of numerous methodologies for their synthesis, these techniques frequently necessitate intricate, multi‐stage protocols and specialized equipment. This study introduces a novel approach for fabricating nanostructured carbon‐ceramic multimaterials through polymerization‐induced microphase separation 3D printing. By combining inorganic precursors, polycarbosilane, and acrylonitrile (AN) within a photocurable resin, heterogeneous nanostructured materials composed of PAN‐preceramic and sacrificial polymer phases are 3D printed. Upon pyrolysis, PAN‐preceramic domains transformed into a carbon‐ceramic matrix while sacrificial polymer domains thermally decomposed to yield nanoscale voids. The utilization of synchrotron X‐ray spectroscopy and microscopy techniques revealed that the phase compositions and microstructure of the resulting multi‐materials are significantly influenced by the initial composition of the resins. The co‐existence of ceramic and carbon phases within a single 3D printed material brought together a combination of properties from both phases, such as the low thermal conductivity of ceramics and the relatively high electrical conductivity of carbon, along with the exceptional chemical resistance. The insights into the microstructure, atomic configuration, and property relationships of the resulting materials have broad implications for the development of multi‐phase nanostructured hybrid materials. [ABSTRACT FROM AUTHOR]

Ion‐exchange materials are commonly composed of polyelectrolyte networks in which crosslinking preserves macroscopic geometry and prevents dissolution in aqueous conditions. However, crosslinking inherently inhibits efficient swelling and mass transfer during ion‐exchange processes. Herein, a one‐step polymerization‐induced microphase separation (PIMS) approach directly using water and linear polystyrene sulfonate macromolecular chain transfer agents (macroCTAs) is developed to engineer bicontinuous nanostructured materials with rapid ion‐exchange capabilities. These materials feature water‐swollen liquid‐like polyelectrolyte domain embedded in a rigid polymer network, where the domain spacing, as determined by small angle X‐ray scattering experiments, is precisely modulated between 15 and 89 nm based on the molecular weight of the macroCTA used. As the bicontinuous nanostructure enables rapid mass transfer throughout the material bulk, the 3D printed PIMS materials are able to rapidly remove model charged dyes from solution, exhibiting a mass transfer coefficient ≈35 times higher than commercially available counterparts. This work is the first example demonstrating direct self‐assembly of water into continuous nanochannels in a well‐controlled manner as supported by time‐resolved small‐angle neutron scattering experiments during polymerization. Moreover, these nanostructured materials are readily produced using commercially available 3D printers, enabling unparalleled high‐resolution fabrication of targeted complex structures, including accurately controllable macroporous geometries and surface areas. [ABSTRACT FROM AUTHOR]