Comb and bottlebrush polymers present a wide range of rheological and mechanical properties that can be controlled through their molecular characteristics, such as the backbone and side chain lengths as well as the number of branches per molecule or the grafting density. This review investigates the impact of these characteristics specifically on the zero shear viscosity, strain hardening behavior, and plateau shear modulus. It is shown that for a comb polymer with an entangled backbone and entangled side chains, a maximum in the strain hardening factor and minimum in the zero shear viscosity η can be achieved through selection of an optimum number of branches q. Bottlebrush polymers with flexible filaments and extremely low plateau shear moduli relative to linear polymers open the door for a new class of solvent-free supersoft elastomers, where their network modulus can be controlled through both the degree of polymerization between crosslinks, n , and the length of the side chains, n , with .
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http://dx.doi.org/10.1002/adma.201806484 | DOI Listing |
Macromol Rapid Commun
January 2025
Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
Janus graft copolymers, which combine the characteristics of block and graft copolymers, have been used in the fields of reaction catalysis, surface modification, and drug delivery, but their applications in lithium batteries have rarely been reported. Herein, Janus graft copolymers with polyethylene glycol (PEG) and polystyrene (PS) side chains are synthesized by combining reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP) methods and doped with lithium salts to fabricate Janus bottlebrush polymer electrolytes (PEG-J-PS). The PEG side chains of the brush polymers impart good ion-conducting properties to the electrolytes, while the PS side chains improve the mechanical strength and thermal and chemical stability of the electrolytes.
View Article and Find Full Text PDFACS Nano
January 2025
Conte Center for Polymer Research, Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States.
Bottlebrush block copolymers (BBCPs) are a unique class of materials that contain a backbone with densely grafted and chemically distinct polymeric side chains. The nonlinear architecture of BBCPs provides numerous degrees of freedom in their preparation, including control over key parameters such as grafting density, side chain length, block arrangement, and overall molecular weight. This uniquely branched structure provides BBCPs with several important distinctions from their linear counterparts, including sterically induced side chain and backbone conformations, rapid and large self-assembled nanostructures, and reduced or eliminated entanglement effects (assuming sufficient grafting density and that the molecular weight of the side chains is below their respective entanglement molecular weight).
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Tianjin University, Material Science and Engineering, 135 Yaguan Rd, Haihe Education Park, 300350, Tianjin, CHINA.
Self-assembled bottlebrush block copolymers (BBCPs) offer a vibrant, eco-friendly alternative to traditional toxic pigments and dyes, providing vivid structural colors with significantly reduced environmental impact. Scaling up the synthesis of these polymers for practical applications has been challenging with conventional batch methods, which suffer from slow mass and heat transfer, inadequate mixing, and issues with reproducibility. Precise control over molecular weight and dispersity remains a significant challenge for achieving finely tuned color appearances.
View Article and Find Full Text PDFNano Lett
January 2025
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Plant genetic engineering methods are critical for food security and biofuel production and to enable molecular farming. Here, we elucidated how polymeric high aspect ratio nanocarriers can enable DNA delivery to plants and transient expression. We demonstrated that a nanocarrier with 20 nm width, 80 nm length, and a polymer-to-DNA ratio of N/P = 3.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Graft-through ring-opening metathesis polymerization (ROMP) of norbornene-terminated macromonomers (MMs) prepared using various polymerization methods has been extensively used for the synthesis of bottlebrush (co)polymers, yet the potential of ROMP for the synthesis of MMs that can subsequently be polymerized by graft-through ROMP to produce new bottlebrush compositions remains untapped. Here, we report an efficient "ROMP-of-ROMP" method that involves the synthesis of norbornene-terminated poly(norbornene imide) (PNI)-based MMs that, following ROMP, provide new families of bottlebrush (co)polymers and "brush-on-brush" hierarchical architectures. In the bulk state, the organization of the PNI pendants drives bottlebrush backbone extension to enable rapid assembly of asymmetric lamellar morphologies with large asymmetry factors.
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