How to better control polymer chemistry

Abstract

A catalytic method yields a strong, adhesive polymer with controlled stereochemistry

Sequence Control from Mixtures: Switchable Polymerization Catalysis and Future Materials Applications

“…The drive toward circular plastics economies targets renewably sourced, degradable/recyclable PSAs with a lower environmental footprint. The oxygenated block polymers afforded by these switchable catalyses should show better controlled degradation chemistries, and their high oxygen content should improve substrate adhesion, particularly for glass, metal, and natural tissues. , There is already good precedent for polyester-based PSAs, their potential being established by Long and co-workers . Grinstaff and co-workers later showed that CO 2 -derived polycarbonates are also promising PSA candidates .…”

Rapid Photoswitching of Low Molecular Weight Arylazoisoxazole Adhesives

“…Molecular photoswitches change structure and function upon irradiation − and continue to hold great promise for the design of active materials that swiftly and reversibly exhibit disparate properties. , Photoreversible surface adhesion, in particular, is rapidly gaining attention over thermal adhesives because of its spatiotemporal control, that is, the stimulus is local and instant in comparison to heat transfer. , Additionally, although the photocuring of the adhesive requires a transparent surface, it avoids the need for assembly of the components at elevated temperatures, requires less energy input, and is independent of heat capacity, opening up to more efficient and new (multifunctional) applications. Although polymeric materials provide sufficient and tunable bulk material properties suitable for reversible surface adhesion with remarkable strength, − they are difficult to synthesize, and repeated use can result in fatigue of the molecular components. , Ideally, components are of low molecular weight (LMW), facilitating both strong intermolecular (cohesive) and interfacial (adhesive) interactions independent of the surface material . Azo compounds are an especially promising class of photoswitches as the glass transition temperature ( T g ) of their polymer E- and Z-isomers can vary, ,,− giving rise to photoreversible adhesives with addressable soft moldable and hardened polymeric structures ( T g,Z < T room < T g,E ). ,,− …”

“…Although polymeric materials provide sufficient and tunable bulk material properties suitable for reversible surface adhesion with remarkable strength, 9−11 they are difficult to synthesize, and repeated use can result in fatigue of the molecular components. 12,13 Ideally, components are of low molecular weight (LMW), facilitating both strong intermolecular (cohesive) and interfacial (adhesive) interactions independent of the surface material. 14 Azo compounds are an especially promising class of photoswitches as the glass transition temperature (T g ) of their polymer E-and Z-isomers can vary, 1,5,15−17 giving rise to photoreversible adhesives with addressable soft moldable and hardened polymeric structures (T g,Z < T room < T g,E ).…”

Constructing Crystalline Porous Polyacetylene Frameworks via Catalyst-free Solid-state Cross-linking in Confined Space

“…Solid-state polymerization (SSP) has provided a promising solution because it can force chemical reactions to proceed with a minimum amount of atomic and molecular movement through solid state confinement and preorganization. [22][23][24] Due to the lack of solvation, the reactants are almost "naked" in a confined space and ready for reaction with lower activation energy. [25][26][27] Therefore, solid-state reactions can occur without additional catalysis.…”