In situ SAXS studies of a prototypical RAFT aqueous dispersion polymerization formulation: monitoring the evolution in copolymer morphology during polymerization-induced self-assembly

Abstract

In situ small-angle X-ray scattering is used to monitor the formation of diblock copolymer spheres, worms and vesicles during reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization of 2-hydroxypropyl methacrylate.

Polymer Self-Assembly Induced Enhancement of Ice Recrystallization Inhibition

“…Higher-order morphologies such as worm-like micelles and polymersomes are typically being observed, resulting in higher packing density for the copolymer chains compared to spherical (micellar) particles. 57 , 58 The versatility of this method has allowed the synthesis of nanoparticles for drug delivery, 59 − 62 cell storage, 63 − 65 and permeable nanoreactors, 66 − 69 and has been extensively reviewed. 70 − 73 PVA-graft-macroinitiators have been reported to lead to polymer nanoparticles with enhanced IRI (compared to the already very potent IRI activity of PVA), potentially due to the high local PVA density arising from PISA.…”

Small‐Angle X‐Ray Scattering Studies of Block Copolymer Nano‐Objects: Formation of Ordered Phases in Concentrated Solution During Polymerization‐Induced Self‐Assembly

“…Relatively featureless patterns were recorded within the first 28 min of the reaction, suggesting the presence of soluble copolymer chains and/or the formation of relatively loose, ill‐defined aggregates. Unlike in situ SAXS studies of more dilute formulations in which well‐defined local minima signified the formation of nano‐objects, [53–55] there was no evidence for any particle form factor. Instead, only a broad structure peak was detected (Figure 2 A).…”

“…[50] Inspecting Figure 2A,B), several stages of structural organization could be identified from the significant changes observed in the SAXS patterns as the BzMA polymerization progressed. Relatively featureless patterns were recorded within the first 28 min of the reaction, suggesting the presence of soluble copolymer chains and/or the formation of relatively loose,i ll-defined aggregates.U nlike in situ SAXS studies of more dilute formulations in which well-defined local minima signified the formation of nano-objects, [53][54][55] there was no evidence for any particle form factor.I nstead, only ab road structure peak was detected (Figure 2A). This feature became increasingly intense,a nd the peak maximum gradually shifted to lower q over the first 58 min of the polymerization (Figure S3).…”

“…In the present study,the evolution of copolymer morphology during PISA was monitored using time-resolved SAXS when targeting PhBD 80 -PBzMA 40 worms at 40 %w /w solids.W ea nd others have previously studied the in situ evolution in copolymer morphology for various PISA formulations. [53][54][55][56] This approach enables the onset of micellization to be identified, as well as the observation of sphere-toworm and worm-to-vesicle transitions during the polymerization. [50] Inspecting Figure 2A,B), several stages of structural organization could be identified from the significant changes observed in the SAXS patterns as the BzMA polymerization progressed.…”

Synthesis of diblock copolymer spheres, worms and vesicles via RAFT aqueous emulsion polymerization of hydroxybutyl methacrylate

“…16 More specifically, the geometric packing para-meter 17 for the copolymer chains governs the preferred morphology provided that certain other criteria are met, such as a suitably short steric stabilizer block and a sufficiently high copolymer concentration. 11 Typically, spheres, [18][19][20] worms 19,21 or vesicles [22][23][24][25][26][27][28] can be obtained using this approach, but lamellae have also been observed. 15,29,30 In particular, reversible addition-fragmentation chain transfer (RAFT) polymerization has enabled the controlled polymerization of many waterimmiscible monomers such as styrene, n-butyl acrylate, methyl methacrylate, vinyl acetate, benzyl methacrylate, glycidyl methacrylate and 2,2,2-trifluoroethyl methacrylate.…”