New materials that have the ability to reversibly adapt to their environment and possess a wide range of responses ranging from self-healing to mechanical work are continually emerging. These adaptive systems have the potential to revolutionize technologies such as sensors and actuators, as well as numerous biomedical applications. We will describe the emergence of a new trend in the design of adaptive materials that involves the use of reversible chemistry (both non-covalent and covalent) to programme a response that originates at the most fundamental (molecular) level. Materials that make use of this approach - structurally dynamic polymers - produce macroscopic responses from a change in the material's molecular architecture (that is, the rearrangement or reorganization of the polymer components, or polymeric aggregates). This design approach requires careful selection of the reversible/dynamic bond used in the construction of the material to control its environmental responsiveness.

As the macromolecular version of mechanically interlocked molecules, mechanically interlocked polymers are promising candidates for the creation of sophisticated molecular machines and smart soft materials. Poly[]catenanes, where the molecular chains consist solely of interlocked macrocycles, contain one of the highest concentrations of topological bonds. We report, herein, a synthetic approach toward this distinctive polymer architecture in high yield (~75%) via efficient ring closing of rationally designed metallosupramolecular polymers. Light-scattering, mass spectrometric, and nuclear magnetic resonance characterization of fractionated samples support assignment of the high-molar mass product (number-average molar mass ~21.4 kilograms per mole) to a mixture of linear poly[7-26]catenanes, branched poly[13-130]catenanes, and cyclic poly[4-7]catenanes. Increased hydrodynamic radius (in solution) and glass transition temperature (in bulk materials) were observed upon metallation with Zn.

Direct-write 3D printing enables the fabrication of three-dimensional objects via the extrusion from a nozzle. Stimuli responsive materials that shear-thin are well-suited as inks for these 3D printing systems. Poly­(isopropyl glycidyl ether)-block-poly­(ethylene oxide)-block-poly­(isopropyl glycidyl ether) ABA triblock copolymers were synthesized using controlled ring-opening polymerization to afford dual stimuli-responsive polymers that respond to both shear forces and temperature. These polymers were demonstrated to form hydrogels in water. The gels were observed to be thermoreversibledriven by the lower critical solution temperature of the poly­(isopropyl glycidyl ether) block which helps facilitate loading of the ink into the printer syringe. Rheological studies demonstrated that the gels had a rapid and reversible modulus response to shear stress. Thus, these materials were suitable as inks for direct-write 3D printing, as they were easily extruded during printing and maintained sufficient mechanical integrity which was necessary to support the next printed layer. Printed structures of high aspect ratio pillars and stacked layers were successfully demonstrated. These types of 3D hydrogel structures may ultimately have an impact in the biomedical field for applications such as tissue engineering.

Selective area atomic layer deposition (SA-ALD) offers the potential to replace a lithography step and provide a significant advantage to mitigate pattern errors and relax design rules in semiconductor fabrication. One class of materials that shows promise to enable this selective deposition process are self-assembled monolayers (SAMs). In an effort to more completely understand the ability of these materials to function as barriers for ALD processes and their failure mechanism, a series of SAM derivatives were synthesized and their structureproperty relationship explored. These materials incorporate different side group functionalities and were evaluated in the deposition of a sacrificial etch mask. Monolayers with weak supramolecular interactions between components (for example, van der Waals) were found to direct a selective deposition, though they exhibit significant defectivity at and below 100 nm feature sizes. The incorporation of stronger noncovalent supramolecular interacting groups in the monolayer design, such as hydrogen bonding units or pi–pi interactions, did not produce an added benefit over the weaker interacting components. Incorporation of reactive moieties in the monolayer component that enabled the polymerization of an SAM surface, however, provided a more effective barrier, greatly reducing the number and types of defects observed in the selectively deposited ALD film. These reactive monolayers enabled the selective deposition of a film with critical dimensions as low as 15 nm. It was also found that the selectively deposited film functioned as an effective barrier for isotropic etch chemistries, allowing the selective removal of a metal without affecting the surrounding surface. This work enables selective area ALD as a technology through (1) the development of a material that dramatically reduces defectivity and (2) the demonstrated use of the selectively deposited film as an etch mask and its subsequent removal under mild conditions.

We report the design, synthesis, and evaluation of biodegradable amphiphilic poly(ethylene glycol)-b-polycarbonate-based diblock copolymers containing pendant persistent organic radicals (e.g., PROXYL). These paramagnetic radicalfunctionalized polymers self-assemble into micellar nanoparticles in aqueous media, which preferentially accumulate in tumor tissue via the enhanced permeability and retention (EPR) effect. Through T 1 relaxation NMR studies, as well as magnetic resonance imaging (MRI) studies on mice, we show that these nanomaterials are effective as metal-free, biodegradable MRI contrast agents. We also demonstrate anticancer drugs can be readily loaded into the nanoparticles, conferring therapeutic delivery properties in addition to their imaging properties making these materials potential theranostic agents in the treatment of cancer.

Freshwater bivalves in the superfamily Unionoidea possess distinct male (M)‐ and female (F)‐transmitted mitochondrial DNA (mtDNA). The former evolves independently of and at a significantly faster rate than the latter. Thus, population genetic and phylogenetic analyses of M sequences facilitate the generation of independent estimates of genetic variation and evolutionary relationships which are often more robust than those provided by analyses of F sequences alone. However, M mtDNA's rapid substitution rate often renders polymerase chain reaction (PCR) amplification difficult with ‘universal’ primers. Herein, we report on three pairs of PCR primers that consistently amplify the hypervariable M COII‐COI gene junction region in 25 bivalve genera (Unionoidea: Ambleminae).

For biological polymers like DNA and proteins, supramolecular interactions dictate the folding and assembly of the polymer chains. Advances in synthetic polymer chemistry enable the synthesis of polymers of defined length and composition, but the field has yet to reach the same level of sophistication as nature's polymers. However, the incorporation of just a few supramolecular interactions into a synthetic polymer chain can drastically change the manner in which the polymer assembles and interacts, thereby altering the properties of a polymeric material. This highlight will focus on approaches wherein a low-density of supramolecular functionalities (<10 wt %) were used per polymer chain. How the selection of the appropriate supramolecular functionality (based on the directionality and strength of the interaction), along with the location of these groups on a polymer chain, can afford a spectrum of material properties has been highlighted. At one end, the supramolecular motif can dramatically alter the elasticity of a material, and at the other, the motif can have a more subtle effect like increasing the stability of a micelle. V C 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 457-472KEYWORDS: block copolymers; hydrogen bonds; inclusion compounds and cyclodextrins; materials science; metal-ligand interaction; self-assembly; stimuli-responsive materials; supramolecular chemistry; supramolecular polymers INTRODUCTION In nature, sequence-specific polymers such as DNA, RNA, and proteins are produced as building blocks for self-assembly into higher-order structures. Supramolecular interactions mediate the assembly and folding of these biopolymers into receptors, enzymes, and other biocomponents necessary for cellular processes. Despite our understanding and appreciation of these interactions in the biological context, replicating the complexity of natural systems is a far-sighted goal. It is currently impossible to create a wholly synthetic polymer that is precisely defined in length and an exact arbitrary sequence. However, as the fields of supramolecular chemistry and polymer chemistry continue to advance, our efforts to utilize supramolecular interactions in material design demonstrate a powerful means to control the structure and function of polymeric materials.

b S Supporting Information ' INTRODUCTIONSmall molecule and polymeric liquid crystalline materials have applications in a multitude of areas, ranging from displays, optical/ electronic imaging, data storage, and stress/temperature sensing to chemical/fire resistance and artificial muscle actuation. 1 The design of typical molecular architectures that facilitate thermotropic liquid crystalline behavior is well documented. Molecules with structural anisotropy, i.e., a rigid moiety with high aspect ratio are frequently utilized to impart the order inherent in a liquid crystalline phase. Functionalization of these cores with flexible alkane chains of varying length then provides the structural complexity necessary to hinder crystallization while preserving liquid crystalline order. As such, thermotropic liquid crystals are inherently stimuli-responsive, as they can undergo a range of thermally induced transitions between glassy/crystalline, liquid crystalline, and isotropic states. Examples of thermotropic liquid crystalline small molecules or polymers that are also designed to respond to specific chemical stimuli are less prevalent. 2 One approach to designing a chemo-responsive liquid crystal involves incorporating a metal-binding ligand into the mesogenic core. In addition to introducing additional, nonthermal, stimuliresponsive behavior incorporation of metal ions into liquid crystalline materials offers the opportunity to impart a number of additional properties upon these systems. Chemical sensing, 3 catalysis, 4 and a host of biological applications 5 highlight the many practical properties of organic metal-coordinating species, while some specific lanthanide complexes also exhibit interesting luminescent and paramagnetic properties. 6 Additionally, the vast number of transition and lanthanide metal ions offers a multitude of potential geometries and binding motifs, which can be utilized to design the specific shapes necessary to retain, induce, or otherwise impact liquid crystallinity. This approach enhances the traditional thermotropic liquid crystal in two ways. First, ligands can be envisioned that, upon binding a metal ion, lose their original liquid crystalline order and thus offer a useful method of amplification for detection schemes and other applications. 7 Second, ligands that bind metal ions and retain, change, or acquire liquid crystalline order (metallomesogens) can also be envisaged. 8 The 2,6-bisbenzimidazolylpyridine (Bip) ligand offers a versatile scaffold from which highly functionalized derivatives can be accessed (e.g., 1 Et , Figure 1). 9,10 Piguet and co-workers have prepared a number of low molecular weight mesogenic Bip derivatives and investigated the effects of metal binding on their liquid crystalline properties. 11 Noting that the incorporation of a large metal center disrupts the organization of simpler Bip mesogens, 12 they decorated the Bip core with a highly alkylated liquid crystallinity-enhancing moiety in the 5 0 positions, which allowed access to a range of metallomeso...