This in-depth review covers progress in the area of polyferrocenylsilanes (PFS), a well-established, readily accessible class of main chain organosilicon metallopolymer consisting of alternating ferrocene and organosilane units. Soluble, high molar mass samples of these materials were first prepared in the early 1990s by ring-opening polymerisation (ROP) of silicon-bridged [1]ferrocenophanes (sila[1]ferrocenophanes). Thermal, transition metal-catalysed, and also two different living anionic ROP methodologies have been developed: the latter permit access to controlled polymer architectures, such as monodisperse PFS homopolymers and block copolymers. Depending on the substituents, PFS homopolymers can be amorphous or crystalline, and soluble in organic solvents or aqueous media. PFS materials have attracted widespread attention as high refractive index materials, electroactuated redox-active gels, fibres, films, and nanoporous membranes, as precursors to nanostructured magnetic ceramics, and as etch resists to plasmas and other radiation. PFS block copolymers form phase-separated iron-rich, redox-active and preceramic nanodomains in the solid state with applications in nanolithography, nanotemplating, and nanocatalysis. In selective solvents functional micelles with core-shell structures are formed. Block copolymers with a crystallisable PFS core-forming block were the first to be found to undergo "living crystallisation-driven self-assembly" in solution, a controlled method of assembling block copolymers into 1D or 2D structures that resembles a living covalent polymerisation, but on a longer length scale of 10 nm-10 μm.

A new and generic method for protein capture-release by polyelectrolyte brushes and pH control.

We report for the first time that the protonation behavior of weak polyelectrolyte brushes depends very strongly on ionic strength. The p K a changes by one pH step per order of magnitude in salt concentration. For low salt concentrations (∼1 mM), a very high pH is required to deprotonate a polyacidic brush and a very low pH is required to protonate a polybasic brush. This has major consequences for interactions with other macromolecules, as the brushes are actually almost fully neutral when believed to be charged. We propose that many previous studies on electrostatic interactions between polyelectrolytes and proteins have, in fact, looked at other types of intermolecular forces, in particular, hydrophobic interactions and hydrogen bonds.

The synthesis and thermoresponsive properties of surface-attached poly( N -isopropylacrylamide)- co - N , N ′-methylene bisacrylamide (PNIPAM- co -MBAM) networks are investigated. The networks are formed via SI-ARGET-ATRP (“grafting-from”) on thiol-based initiator-functionalized gold films. This method is reliable, well controlled, fast, and applicable to patterned surfaces ( e.g. , nanopores) for networks with dry thicknesses >20 nm. Surface-attached PNIPAM- co -MBAM gels are swollen below their volume phase transition temperature but above collapse without complete expulsion of water (retain ∼50 vol %). The swelling/collapse transition is studied using complementary SPR and QCMD techniques. The ratio between swollen and collapsed heights characterizes the thermoresponsive behavior and is shown to not depend on network height but to vary with MBAM content. The higher the proportion of the crosslinker, the lower the magnitude of the phase transition, until all responsiveness is lost at 5 mol % MBAM. The temperature range of the transition is broadened for more crosslinked PNIPAM- co -MBAM gels but remains centered around 32 °C. Upon reswelling, less crosslinked networks display sharp transitions, while for those containing ≥3 mol % MBAM, transitions remain broad. This tunable behavior persists for gels on nanostructured gold surfaces. Investigating PNIPAM- co -MBAM networks on gold plasmonic nanowell arrays is a starting point for expanding their scope as thermo-controlled nanoactuators.

The solution self-assembly of a heterobimetallic diblock copolymer with a crystallisable poly(ferrocenyldimethylsilane) (PFS) core-forming block and a corona-forming segment featuring a poly(cobaltoceniumethylene) (PCE) based polyelectrolyte/surfactant complex, PFS50-b-[PCE][AOT]50 (AOT = bis(2-ethylhexyl) sulfosuccinate), has been explored. 2 Fiber-like micelles were formed in selective solvents for the Co block, presenting a corona in which every repeat unit bears a charge. We found that key features of the 1D morphologies were dependent on both the polarity of the solvent medium and temperature. In the most polar of the explored solvent media (iPrOH), seeded growth from 1D seeds of PFS50-b-P2VP739 (P2VP = poly(2-vinylpyridine)) yielded tapered B-A-B triblock co-micelles, where the width of the terminal B region derived from PFS-b-[PCE][AOT]n reduced on moving from the interface with the seed to the micelle termini. In addition, ca. 30 % of the micelles featured branching to yield multiple terminal blocks. On reducing the polarity of the solvent medium by the addition of 20% THF, the tapering of the micelles was no longer apparent, and the degree of branching was substantially increased to ca. 100 % of the population. With increased amounts of THF (30 %) the degree of branching reduced dramatically to ca. 3 %. In the least polar medium investigated (1:10 iPrOH:EtOAc), linear triblock co-micelles formed in which the terminal blocks were of consistent diameter, with no evidence for tapering or branching. However, significant unsymmetric growth (i.e. a higher degree of growth from one seed terminus compared to the other) to give noncentrosymmetric A-B diblock co-micelles was detected. Post self-assembly modification by coronal counterion exchange to alter the chemistry and solubility of the corona was also possible.

Polymetallocenes based on ferrocene, and to a lesser extent cobaltocene, have been well‐studied, whereas analogous systems based on nickelocene are virtually unexplored. It has been previously shown that poly(nickelocenylpropylene) [Ni(η5‐C5H4)2(CH2)3]n is formed as a mixture of cyclic (6x) and linear (7) components by the reversible ring‐opening polymerisation (ROP) of tricarba[3]nickelocenophane [Ni(η5‐C5H4)2(CH2)3] (5). Herein the generality of this approach to main‐chain polynickelocenes is demonstrated and the ROP of tetracarba[4]nickelocenophane [Ni(η5‐C5H4)2(CH2)4] (8), and disila[2]nickelocenophane [Ni(η5‐C5H4)2(SiMe2)2] (12) is described, to yield predominantly insoluble homopolymers poly(nickelocenylbutylene) [Ni(η5‐C5H4)2(CH2)4]n (13) and poly(tetramethyldisilylnickelocene) [Ni(η5‐C5H4)2(SiMe2)2]n (14), respectively. The ROP of 8 and 12 was also found to be reversible at elevated temperature. To access soluble high molar mass materials, copolymerisations of 5, 8, and 12 were performed. Superconducting quantum interference device (SQUID) magnetometry measurements of 13 and 14 indicated that these homopolymers behave as simple paramagnets at temperatures greater than 50 K, with significant antiferromagnetic coupling that is notably larger in carbon‐bridged 6x/7 and 13 compared to the disilyl‐bridged 14. However, the behaviour of these polynickelocenes deviates substantially from the Curie–Weiss law at low temperatures due to considerable zero‐field splitting.

We investigate types of ring strain responsible for the ring-opening polymerisation of [n]nickelocenophanes with carbon and silicon-based ansa bridges.

Interfaces functionalized with polymers are known for providing excellent resistance towards biomolecular adsorption and for their ability to bind high amounts of protein while preserving their structure. However, making an interface that switches between these two states has proven challenging and concepts to date rely on changes in the physiochemical environment, which is static in biological systems. Here we present the first interface that can be electrically switched between a high‐capacity (>1 μg cm−2) multilayer protein binding state and a completely non‐fouling state (no detectable adsorption). Switching is possible over multiple cycles without any regeneration. Importantly, switching works even when the interface is in direct contact with biological fluids and a buffered environment. The technology offers many applications such as zero fouling on demand, patterning or separation of proteins as well as controlled release of biologics in a physiological environment, showing high potential for future drug delivery in vivo.