Title:
Synthesis, Properties, and Assemblies of Uniform Polymer-ligated Nanocrystals
Synthesis, Properties, and Assemblies of Uniform Polymer-ligated Nanocrystals
Author(s)
Liang, Shuang
Advisor(s)
Lin, Zhiqun
Editor(s)
Collections
Supplementary to
Permanent Link
Abstract
Colloidal synthesis represents one of the most widely used strategies to produce inorganic nanocrystals for a variety of applications in optoelectronics, catalysis, biotechnology, among other areas. Despite significant advances achieved in the past two decades, the capability of developing functional inorganic nanocrystals (NCs) with versatile morphology, uniform dimension, outstanding stabilities, tunable compositions, desirable physical properties, and tailorable surface chemistry remains challenging. Therefore, in this dissertation, we aim to capitalize on an array of nonlinear block copolymers with tunable and precisely controlled dimensions, compositions and architectures as nanoreactors to craft inorganic NCs of distinctive compositions with uniform morphology, enhanced stabilities, and desirable surface chemistry, which is unattainable by conventional colloidal synthesis. As a consequence, the intriguing size-, shape-, and composition-dependent physical properties of these inorganic NCs as well as the relationship between surface chemistry and physical properties can be scrutinized. Furthermore, the applications of polymer-ligated inorganic NCs are exemplified in optoelectronics, photocatalysis, and drug delivery. Specifically, the key findings of this dissertation are reflected as follows:
First, a set of uniform metal chalcogenide semiconducting nanoparticles (NPs) were in-situ crafted via a diversity of star-like block copolymer nanoreactors, yielding uniform morphology, variable surface chemistry, size-dependent NIR optical properties, and remarkable air tolerance. The outer blocks of star-like block copolymers were covalently connected to the inner core and thus permanently situated on the surface of as-prepared NPs, suggesting the formation of a stable protective polymer shell over each individual NP and thus markedly improved air stability of NPs. Most importantly, the effects of surface chemistry on the air stability of these lead chalcogenide NPs were unraveled by judiciously alternating the compositions and chain lengths of polymers that perpetually tethered outside the NPs, providing essential fundamental understandings for the synthesis and design of stable semiconducting NPs.
Second, we designed and synthesized a series of star-like PAA-b-P3HT block copolymers for crafting uniform, highly stable P3HT-ligated metal halide perovskite NPs. For the first time, we realized the ligation of semiconducting conjugated polymers on the surface of perovskite NPs during in-situ colloidal synthesis. The formation of type-II electronic band alignment between P3HT and perovskite NPs yielded efficient interfacial charge carriers separation, which are then found to be pronouncedly affected by the molecular weight (MW) of tethered P3HT and size of perovskite NPs. As a result, the P3HT-ligated perovskite NPs exhibited promising potential as robust photocatalysts.
Third, extended from star-like block copolymer, we demonstrated a universal strategy to produce a variety of 1D perovskite nanorods (NRs) of distinctive compositions with stable, uniform and tailored morphology via capitalizing on amphiphilic bottlebrush-like block copolymers (BBCPs) as nanoreactors. The synthesis route affords an unprecedented and ideal platform for scrutinizing their dimension-dependent physical properties, which has yet to be explored, while imparts remarkable structural and optical stabilities as well upon ambient storage and against heat, UV irradiation, and polar solvents.
Fourth, self-assembly of polymer-ligated inorganic NCs were performed via three routes. In the first route, the PS-ligated perovskite NRs were assembled into periodic patterns through controlled evaporative self-assembly in confined geometry. In the second route, the chain ends of star-like block copolymers were functionalized with complementary hydrogen bonding moieties prior to acting as nanoreactors to direct the growth of perovskite NPs. The self-assembly of perovskite NPs of tailorable morphology can then be realized via regulating the mixing temperature to manipulate hydrogen bonding, resulting in varied inter-particle interaction and exciton coupling in perovskite NPs. In the third route, light-responsive polymers (i.e., PMAMC) were incorporated in the synthesis of cellulose-g-(PAA-b-PMAMC) BBCPs which were then used as cylindrical nanoreactors to yield light-responsive PMAMC-ligated Au NRs. The light responsiveness of PMAMC blocks induce reversible and stable self-assembly/disassembly of Au NRs under UV light irradiation of different wavelengths, which pronouncedly depends on the chain length of PMAMC blocks, indicating potential application in drug delivery.
In summary, advances in colloidal synthesis and self-assembly of inorganic NCs were achieved by utilizing rationally designed nonlinear block copolymers, yielding NCs with variable architectures, uniform and tunable dimensions, controlled compositions, as well as versatile, stable and well-defined surface chemistry. Therefore, the structure-composition-property correlations of a myriad of inorganic NCs can be revealed, suggesting promising opportunity to apply them for a variety of practical applications.
Sponsor
Date Issued
2022-06-21
Extent
Resource Type
Text
Resource Subtype
Dissertation