| NSF Org: |
DMR Division Of Materials Research |
| Recipient: |
|
| Initial Amendment Date: | June 23, 2017 |
| Latest Amendment Date: | August 29, 2018 |
| Award Number: | 1725414 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Peter Anderson
DMR Division Of Materials Research MPS Directorate for Mathematical and Physical Sciences |
| Start Date: | October 1, 2017 |
| End Date: | September 30, 2021 (Estimated) |
| Total Intended Award Amount: | $500,000.00 |
| Total Awarded Amount to Date: | $687,500.00 |
| Funds Obligated to Date: |
FY 2018 = $187,500.00 |
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
3227 CHEADLE HALL SANTA BARBARA CA US 93106-0001 (805)893-4188 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
CA US 93106-5121 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | DMREF |
| Primary Program Source: |
01001819DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.049 |
ABSTRACT
Non-technical Description: Block polymers are macromolecules that contain segments or 'blocks' of repeated polymerized monomers of at least two types. Much as proteins have tremendous variation in property and function in biological systems by virtue of the choice and placement of amino acid residues along the polymer backbone, the properties of block polymers can be widely tuned by varying the length, placement, and chemical identity of their constituent blocks. Block polymers are the basis for many important types of soft materials such as elastomers and adhesives, but are increasingly important in applications such as advanced membranes for batteries and fuel cells, medical devices, and soft templates for patterning microelectronic devices. A current challenge in deploying block polymers in such applications is that the chemical design space is vast and there is very limited data and predictive ability connecting the chemical structure to the derivative properties in a given material. This project aims to dramatically accelerate block polymer materials discovery by closely coupling modern theory and simulation approaches with state-of-the-art synthesis and characterization. Through extensive experimental feedback to validate and continuously improve models and simulation methods, the project will build the foundations for a future in which in silico design of block polymers is routine.
Technical Description: Block polymers are attractive for creating advanced materials with novel functionality by embedding multiple physical or chemical properties within a single compound. Such polymers are also attractive for manufacturing as their synthesis is scalable and they embed nanostructures spontaneously by thermodynamic driving forces arising from the incompatibility of the different blocks. However, as the demand for distinct desirable properties exhibited by a single material increases, so must the number of blocks. The corresponding design space increases geometrically with the number of blocks and block chemistries, making an intuition-based, trial-and-error approach infeasible. Instead, the project adopts a computationally-driven materials discovery approach, building on recent game-changing advances in self-consistent field theory and global optimization strategies for materials design and discovery. These computational strategies are coupled to an ambitious, advanced synthesis and characterization program capable of realizing the desired materials in practice. Through experimental feedback to validate and continuously improve models and simulation methods, the project will build the foundations for a future in which in silico design of block polymers is routine.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
This collaborative project between the University of California, Santa Barbara (UCSB) and the University of Minnesota (UMN) aimed to build an integrated and iterative experimental and computational approach for discovering novel block polymer molecular architectures and formulations that are capable of self-assembling into mesoscopically ordered phases with symmetries and length scales appropriate for applications to photonic crystals.
Intellectual Merit:
Block copolymers are polymer chains with segments selected from two or more chemistries and arranged in contiguous "block" sequences. Their spontaneous self-assembly into spatially periodic nanostructures is well established. However, there are significant challenges for photonic applications in the visible spectrum: the length scales of the assembled structures are too small, the contrast of optical constants between common chemistries is too weak, and the network-like 3D structures most promising for photonic applications are compositionally delicate and difficult to stabilize. Exploring the vast space of candidate chemistries, molecular architectures, and composition sequences to overcome these limitations is an enormous challenge and motivates our iterative feedback between experimental observations (UMN team) and computational predictions (UCSB team).
The challenge of length scales focused our research on the bottle-brush block polymer architecture, which features a backbone polymer strand to which side polymer chains of different species are densely attached in designed sequences. Such molecules have been shown to self-assemble into structures with length scales that are in the appropriate regime for photonic applications, but controlling the symmetries of self-assembled structures is challenging due to grafting-induced stiffening.
Our project leveraged computational materials discovery tools that we developed under a previous award to build a computational workflow for predicting photonic band structures from a specification of block polymer architecture and composition. This workflow was used to optimize molecular architecture and sequences to predict the stability of two phases of particular interest: a non-centrosymmetric (lacking a center of inversion symmetry) lamellar phase with long domain periods ~100nm, and an "optical" single-gyroid phase, which features a complete 3D photonic band gap, obtained from a "structural" double-gyroid phase by optical matching between two of the domains. In addition to these materials-design outcomes, we elucidated some fundamental features of the self-assembly of bottlebrush block polymers, including the orientation of molecular backbones relative to domain interfaces for random and blocky side-chain sequences, the resulting sensitivity to that orientation of the scaling of domain spacing with respect to molecular weight, how the predicted order-disorder transition depends universally on the ratio between length of the side chains and the backbone, and the observation of a transition to star-polymer-like self-assembly as the bottle-brush backbone is made extremely short. These findings guide design rules for future materials applications.
Broader Impact:
This award supported the training of one postdoctoral scholar and two graduate students (one female). These participants have developed skills in simulation and modeling, high-performance computing, data management, collaborating with experimentalists, and polymer physics. Using the computational techniques partially developed in this award, the postdoctoral scholar engaged industrial partners and communicated concepts for designing elastomeric materials with a unique profile of mechanical properties using novel types of branched block polymer architectures. These proposals were further adapted to be robust to the molecular architecture and composition fidelity loss of at-scale production. Simulation data related to the self-assembly of bottle-brush block polymers were uploaded to Citrination, an online materials data repository managed by Citrine Informatics, and new software tools were developed to facilitate such uploads in the future. Open-source inverse-design tools were made available on our project's UMN-hosted website (pscf.cems.umn.edu). Project findings were reported annually by participants at the March Meeting of the American Physical Society and at UCSB's Annual Review of the Complex Fluids Design Consortium. Participants of the project have been involved in K-12 science outreach activities, including hands-on model solar car building and soft robotics workshops for elementary school students and area high-school teachers.
Last Modified: 10/28/2021
Modified by: Kris T Delaney
Please report errors in award information by writing to: awardsearch@nsf.gov.
