Advanced applications of polymeric self-assembled structures require a stringent degree of control over such aspects as functionality location, morphology and size of the resulting assemblies. A loss of control in the polymeric building blocks of these assemblies can have drastic effects upon the final morphology or function of these structures. Gaining precise control over various aspects of the polymers, such as chain lengths and architecture, blocking efficiency and compositional distribution is a challenge and, hence, measuring the intrinsic mass and size dispersity within these areas is an important aspect of such control. It is of great importance that a good handle on how to improve control and accurately measure it is achieved. Additionally dispersity of the final structure can also play a large part in the suitability for a desired application. In this Tutorial Review, we aim to highlight the different aspects of dispersity that are often overlooked and the effect that a lack of control can have on both the polymer and the final assembled structure.

In this paper, we describe the use of liquid cell transmission electron microscopy (LCTEM) for inducing and imaging the formation of spherical micelles from amphiphilic block copolymers. Within the irradiated region of the liquid cell, diblock copolymers were produced which self-assembled, yielding a targeted spherical micellar phase via polymerization-induced self-assembly (PISA). Critically, we demonstrate that nanoparticle formation can be visualized in situ and that in the presence of excess monomer, nanoparticle growth occurs to yield sizes and morphologies consistent with standard PISA conditions. Experiments were enabled by employing automated LCTEM sample preparation and by analyzing LCTEM data with multi-object tracking algorithms designed for the detection of low-contrast materials.

Herein we report a polymerization-induced self-assembly (PISA) process with ring-opening metathesis polymerization (ROMP). We utilize a peptide-based norbornenyl monomer as a hydrophobic unit to provide a range of nanostructures at room temperature yet at high solids concentrations of 20 wt % in combination with an oligoethylene glycol based norbornenyl monomer. Evaluation of the polymerizations under mild conditions highlight that good control is maintained along with high monomer conversion of greater than 99%, indicating that the living polymerization is unaffected during the PISA process. The demonstration broadens the scope of the PISA process to a new living polymerization methodology toward the development of easily accessible and highly functionalized nanostructures in situ.