When polymer chains are grafted to a polymer backbone, a molecular brushes is formed. This polymer architecture is also referred to as a polymer bottlebrush. The close proximity of polymer chains within one bottlebrush molecule endow such polymers with new properties that are distinctly different from linear polymer counterparts. In many ways, bottlebrush polymers are basically one giant polymer construct that comprises nanoscale dimensions. It is this nanoparticle character that has prompted the increasing use of polymer bottlebrushes in the areas of polymer self-assembly, nanomedicine and template chemistry.

Our group has extensive expertise in the synthesis and application of molecular polymer bottlebrushes. Please refer to the following review articles as an introduction to this area of research.

• Molecular Polymer Bottlebrushes in Nanomedicine: Therapeutic and Diagnostic Applications Chem. Commun. 2022, 58, 5683-5716.
• Synthesis and applications of compartmentalised molecular polymer brushes. Angew. Chem. Int. Ed. 2018, 57, 6982-6994.
• Cylindrical Polymer Brushes – Anisotropic Building Blocks, Unimolecular Templates and Particulate Nanocarriers. Polymer 2016, 98, 389-401.
• Molecular Polymer Brushes in Nanomedicine. Macromol. Chem. Phys. 2016, 207 , 2209-2222.

Nature’s countless examples of multi-functional advanced materials are often achieved by bottom-up self-assembly of organic and inorganic building blocks. We are interested in progressing the synthesis of polymeric building blocks that will ultimately allow for a bottom-up construction of superstructures through polymer-polymer and inter-particle associations. The use of block copolymers in self-assembly (solution or bulk) has come a long way. With it came a in-depth understanding about what governs self-assembly and how can it be manipulated.

We are interested in adding new building blocks to the mix. Using molecular bottlebrushes in solution and bulk self-assembly achieves faster self-assembly kinetics and provides access to larger domain spacing. This has led to the development of new surfactants or photonic coatings. We use bottlebrush building blocks that are compartmentalised into domains (e.g. block-type or core-shell).

Bottlebrushes with a core-shell structure can act as cylindrical template to assemble polymers along the brush backbone. Using interpolyelectrolyte complexation we could build uniformly segregated nanowires featuring stacked discs along the brush long axis (see image).

At the same time, we used block-type brushes as a high molecular weight analogue to linear block copolymers and explored their self-assembly in emulsion droplets or solution. Again, we were able to generate stacked lamellae/discs, but this time in the shape of an ellipsoid.

Currently, we explore the above methods further to produce nano-scale discs for biomedical applications. Especially our pioneering concept of using bottlebrush copolymers akin to rod-coil polymers has allowed us to generate functional nanodiscs in water directly.

Selected references:

• Self-Assembly of Thioether-Based Diblock Copolymers: A Comparative Study of Linear and Bottlebrush Architectures. Polym. Chem. 2025, 16, 2244.
• Carborane-Containing Polymer Nanoparticles via Light-Mediated Polymerization-Induced Self-Assembly. Macromolecules 2025, 58, 2237.
• Self-Assembly of Amorphous 2D Polymer Nanodiscs with Tuneable Size, pH-Responsive Degradation and Controlled Drug Release. Angew. Chem. 2025, 64, e202424269.
• Self-Assembly of Rod-Coil Bottlebrush Copolymers into Degradable Nanodiscs with a UV-Triggered Self-Immolation Process. Angew. Chem. 2024, 63, e202318881.
  
• Nanoscale Polymer Discs, Toroids and Platelets Chem. Soc. Rev. 2024, 53, 1984-2021.
• Loop to Linear: Exploring the Impact of Corona Topology on the Properties of Self-Assembled Polymer Nanoparticles. Polym. Chem. 2024, 15, 1659.
• Polymer Nanowires with Highly Precise Internal Morphology and Topography. J. Am. Chem. Soc. 2018, 140, 12736.
• Self-assembly of diblock molecular polymer brushes in the spherical confinement of nanoemulsion droplets. Macromol. Rapid Commun. 2018, 39, 1800177.

Polymer- and nanoparticle-based delivery systems are expected to overcome limitations of traditional drug delivery strategies. While many strides have been made in drug carrier design, the superficial penetration of tumours by nanoparticles remains a key hurdle to treatment success.

In this context, we are mapping a structure-function-property relationship using our molecular polymer bottlebrush nanomaterials. We were one of the first teams to establish that polymer brush-based nanoparticles are promising in nanomedicine applications. Since then, we have understood our nanoparticle platform better and are using our controlled synthesis methods to screen for ideal nanoparticle design parameters with the ultimate goal of improving tissue and tumour penetration of future polymer nanomedicines. Along the way, we have already established that our materials can deliver cytotoxic drugs and accumulate in tumours. Intriguingly, we can use nanoparticle shape, aspect ratio, amphiphilicity and stiffness to influence the how our material interacts with cells in vitro and in vivo. Most recently, we showed that subtle changes to brush stiffness affect their intracellular fate, potentially providing mechanical means to control treatment outcomes in the future.

Recently, we have launched new research direction on injectable biomimetic hydrogels for tissue engineering applications. Stay tuned for updates.

Selected references:

• Self-Assembly of Amorphous 2D Polymer Nanodiscs with Tuneable Size, pH-Responsive Degradation and Controlled Drug Release. Angew. Chem. 2025, 64, e202424269.
• Water-soluble squaramide-functionalised copolymers for anion recognition. Macromol. Rapid Commun. 2023, 2300406.
• Tuning the Hydrophilic – Hydrophobic Balance of Molecular Polymer Bottlebrushes Enhances their Tumor Homing Properties. Adv. Healthcare Mater. 2022, 2200163.
• Stiffness-Dependent Intracellular Location of Cylindrical Polymer Brushes. Macromol. Rapid Commun. 2021, 42, 2100138.
  
• Aspect-ratio-dependent interaction of molecular polymer brushes and multicellular tumour spheroids. Polym. Chem. 2018, 25, 3461.
• A 'Grafting from' Approach to Polymer Nanorods for pH-Triggered Intracellular Drug Delivery. Polymer 2017 ,112, 244.
• Shape-Dependent Activation of Cytokine Secretion by Polymer Capsules in Human Monocyte-Derived Macrophages. Biomacromol. 2016, 17, 1205.
  
• Passive Tumour Targeting and Extravasation of Cylindrical Polymer Brushes in Mouse Xenografts. Chem. Commun. 2016, 52, 9121.
• Size and rigidity of cylindrical polymer brushes dictate long circulating properties in vivo. ACS Nano 2015, 9, 1294.

We have developed several synthetic approaches to produce highly uniform hybrid materials by using innovative molecular scaffolds, in situ nanostructuring or by applying typical template chemistry. Polymers and polymer architectures offer a powerful platform as they allow for precise tailoring of structuring domains at the nanoscale.

We have broaden our materials design to also include renewable resources, such as cellulose or tannins. Using tannic acid, we developed a new hydrogel-based templating method to produce porous nanocrystalline semiconducting materials and tested their performance as lithium-ion battery electrodes. We are now exploring this method to prepare mixed metal oxides for photocatalytic processes.

Selected references:

• Nanostructuring niobium oxides using polymer-grafted cellulose nanocrystals and nanofibers as sacrificial scaffolds. RSC Applied Polym. 2025, 3, 146.
• Polymer Brush-Grafted Cellulose Nanocrystals for the Synthesis of Porous Carbon-Coated Titania Nanocomposites. Polym. Chem. 2023, 14, 2181.
• Fabrication of Nanostructured Carbon-Coated Anatase as Battery Anode Materials with Variable Morphology and Porosity. ACS Appl. Mater. Interfaces 2023, 15, 12261.
• Integrated Polyphenol-Based Hydrogel Templating Method for Functional and Structured Oxidic Nanomaterials. Chem. Mater. 2020, 32, 4716.
• Block Copolymer-Directed Synthesis of Porous Anatase for Lithium-Ion Battery Electrodes. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1890.
  
• Visible Light‐Driven MADIX Polymerisation via a Reusable, Low‐Cost and Non‐Toxic Bismuth Oxide Photocatalyst. Angew. Chem. Int. Ed. 2019, 58, 1828.
• Polymer brush guided templating on well-defined rod-like cellulose nanocrystals. Polym. Chem. 2018, 13, 1650.