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Effects of Grafting Density on Block Polymer Self-Assembly: From Linear to Bottlebrush

Lin, Tzu-Pin and Chang, Alice B. and Luo, Shao-Xiong and Chen, Hsiang-Yun and Lee, Byeongdu and Grubbs, Robert H. (2017) Effects of Grafting Density on Block Polymer Self-Assembly: From Linear to Bottlebrush. ACS Nano, 11 (11). pp. 11632-11641. ISSN 1936-0851. doi:10.1021/acsnano.7b06664.

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Grafting density is an important structural parameter that exerts significant influences over the physical properties of architecturally complex polymers. In this report, the physical consequences of varying the grafting density (z) were studied in the context of block polymer self-assembly. Well-defined block polymers spanning the linear, comb, and bottlebrush regimes (0 ≤ z ≤ 1) were prepared via grafting-through ring-opening-metathesis polymerization. ω-Norbornenyl poly(D,L-lactide) and polystyrene macromonomers were copolymerized with discrete comonomers in different feed ratios, enabling precise control over both the grafting density and molecular weight. Small-angle X-ray scattering experiments demonstrate that these graft block polymers self-assemble into long-range-ordered lamellar structures. For 17 series of block polymers with variable z, the scaling of the lamellar period with the total backbone degree of polymerization (d* ∼ N_(bb)^α) was studied. The scaling exponent α monotonically decreases with decreasing z and exhibits an apparent transition at z ≈ 0.2, suggesting significant changes in the chain conformations. Comparison of two block polymer systems, one that is strongly segregated for all z(System I) and one that experiences weak segregation at low z (System II), indicates that the observed trends are primarily caused by the polymer architectures, not segregation effects. A model is proposed in which the characteristic ratio (C∞), a proxy for the backbone stiffness, scales with N_(bb) as a function of the grafting density: C∞ ∼ N_(bb)^(f(z)). The scaling behavior disclosed herein provides valuable insights into conformational changes with grafting density, thus introducing opportunities for block polymer and material design.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Lin, Tzu-Pin0000-0001-7041-7213
Chang, Alice B.0000-0001-5036-2681
Luo, Shao-Xiong0000-0001-5308-4576
Chen, Hsiang-Yun0000-0002-6461-1519
Lee, Byeongdu0000-0003-2514-8805
Grubbs, Robert H.0000-0002-0057-7817
Additional Information:© 2017 American Chemical Society. Received: September 19, 2017; Accepted: October 26, 2017; Published: October 26, 2017. This work was supported by the Department of Energy under award number DE-AR0000683 (ARPA-E program) and by the National Science Foundation under award number CHE-1502616. A.B.C. thanks the U.S. Department of Defense for support through the NDSEG fellowship. This research used resources of the Advanced Photon Source, a U.S. Department of Energy Office of Science User Facility operated by Argonne National Laboratory under contract DE-AC02-06CH11357. The authors gratefully acknowledge M. A. Hillmyer, F. S. Bates, I. Haugan Smidt, M. J. Maher, and C. M. Bates for helpful discussions. The authors declare no competing financial interest.
Funding AgencyGrant Number
National Defense Science and Engineering Graduate (NDSEG) FellowshipUNSPECIFIED
Department of Energy (DOE)DE-AC02-06CH11357
Subject Keywords:self-assembly, block polymer, bottlebrush, graft polymer, lamellae, scaling
Issue or Number:11
Record Number:CaltechAUTHORS:20171030-123757320
Persistent URL:
Official Citation:Effects of Grafting Density on Block Polymer Self-Assembly: From Linear to Bottlebrush. Tzu-Pin Lin, Alice B. Chang, Shao-Xiong Luo, Hsiang-Yun Chen, Byeongdu Lee, and Robert H. Grubbs. ACS Nano 2017 11 (11), 11632-11641. DOI: 10.1021/acsnano.7b06664
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:82770
Deposited By: Tony Diaz
Deposited On:30 Oct 2017 19:56
Last Modified:15 Nov 2021 19:52

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