Synthesis of Isocyanate-Based Brush Block Copolymers and Their Rapid Self-Assembly to Infrared-Reflecting Photonic Crystals

Miyake, Garret M.; Weitekamp, Raymond A.; Piunova, Victoria A.; Grubbs, Robert H.

doi:10.1021/ja306430k

Cited by 218 publications

(213 citation statements)

References 51 publications

(30 reference statements)

Supporting

Mentioning

213

Contrasting

Order By: Relevance

“…The x-I anchor group has been widely incorporated in macromonomers toward the synthesis of bottlebrush polymers by grafting-through ROMP, 21,55,[57][58][59] motivating our interest in imide-based diluents. Compared to diester anchor groups, imides are more rigid due 4 to their fused rings and thereby change the monomer steric profile.…”

Section: Chart 1 Monomer Design For Ring-opening Metathesis Copolymementioning

confidence: 99%

Design, Synthesis, and Self-Assembly of Polymers with Tailored Graft Distributions

et al. 2017

Self Cite

View full text Add to dashboard Cite

Grafting density and graft distribution impact the chain dimensions and physical properties of polymers. However, achieving precise control over these structural parameters presents long-standing synthetic challenges. In this report, we introduce a versatile strategy to synthesize polymers with tailored architectures via grafting-through ring-opening metathesis polymerization (ROMP). One-pot copolymerization of an ω-norbornenyl macromonomer and a discrete norbornenyl co-monomer (diluent) provides opportunities to control the backbone sequence and therefore the side chain distribution. Toward sequence control, the homopolymerization kinetics of 23 diluents were studied, representing diverse variations in the stereochemistry, anchor groups, and substituents. These modifications tuned the homopolymerization rate constants over two orders of magnitude (0.36 M −1 s −1 < khomo < 82 M −1 s −1 ). Rate trends were identified and elucidated by complementary mechanistic and density functional theory (DFT) studies. Building on this foundation, complex architectures were achieved through copolymerizations of selected diluents with a poly(D,L-lactide) (PLA), polydimethylsiloxane (PDMS), or polystyrene (PS) macromonomer. The cross-propagation rate constants were obtained by non-linear least squares fitting of the instantaneous co-monomer concentrations according to the Mayo-Lewis terminal model. Indepth kinetic analyses indicate a wide range of accessible macromonomer/diluent reactivity ratios (0.08 < r1/r2 < 20), corresponding to blocky, gradient, or random backbone sequences. We further demonstrated the versatility of this copolymerization approach by synthesizing AB graft diblock polymers with tapered, uniform, and inverse-tapered molecular "shapes." Small-angle X-ray scattering analysis of the self-assembled structures illustrates effects of the graft distribution on the domain spacing and backbone conformation. Collectively, the insights provided herein into the ROMP mechanism, monomer design, and homo-and copolymerization rate trends offer a general strategy for the design and synthesis of graft polymers with arbitrary architectures. Controlled copolymerization therefore expands the parameter space for molecular and materials design.

show abstract

Section: Chart 1 Monomer Design For Ring-opening Metathesis Copolymementioning

confidence: 99%

Design, Synthesis, and Self-Assembly of Polymers with Tailored Graft Distributions

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…The characteristics of the PS-g-HIC-N s -l g samples are listed in Table S3. The cross-section mean-square radius of gyration (⟨S c 2 ⟩) for the PS-g-HIC-N s -l g samples was determined from the initial slope in the cross-section Guinier plot, ln[qΔI(q)/C p ] C p =0 versus q 2 , within the cross-section Guinier region (a typical example is shown in Figure 3) by applying the following equation: 36 12) where L is the contour length of the cylinder, k is the electron density contrast factor, and N is the number of cylinders. The values of ⟨S c 2 ⟩ 1/2 for the poly(macromonomer), PS-g-HIC-N s -0.22, at an infinite dilution are listed in Table 2.…”

Section: Macromoleculesmentioning

confidence: 99%

Graft Density Dependence of Main Chain Stiffness in Molecular Rod Brushes

et al. 2015

View full text Add to dashboard Cite

The graft density dependence of main chain stiffness in rod brushes composed of a flexible linear polystyrene (PS) main chain and poly(n-hexyl isocyanate) (PHIC) rod side chains has thoroughly been investigated by static light (LS) and small-angle Xray scattering (SAXS) measurements in tetrahydrofuran (THF) at 25°C. A series of statistical graft copolymers having different graft densities (σ) and graft chain lengths (PS-g-HIC-N s -l g , where N s is the weight-averaged degree of polymerization of HIC and l g is the average distance (spacing) of the main chain between the side chain joints) were prepared by the nearly azeotrope radical copolymerizations of styrene (M 1 ) with PHIC macromonomers (M 2 ) (r 1 = 0.84 ± 0.1 and r 2 = 1.1 ± 0.3) in n-hexane or the bulk at 60°C. The compositional heterogeneities of the graft copolymers were carefully characterized by the ratio of the UV to RI signal in the SEC traces and the comparison with those predicted from the theory by Stejskal and Kratochvil [Macromolecules 1987, 20, 2624], implying that they were sufficiently small enough to allow one to study their dimensional characterizations. The graft density dependence of the root-mean-square cross-section radius of gyration (⟨S c 2 ⟩ 1/2 ) and the z-averaged root-mean-square radius of gyration (⟨S 2 ⟩ z 1/2 ) of PS-g-HIC-N s -l g was studied and rationalized as the function of σ and N s . The σ-dependence of ⟨S c 2 ⟩ 1/2 could be quantitatively described by the theory for the semiflexible comb whose main and side chains have different chain stiffness. The weight-averaged degree of polymerization of the main chain (N M ) dependence of ⟨S 2 ⟩ z 1/2 was also quantitatively described by the cylindrical wormlike chain model. It was found that the change in the main chain stiffness (λ b −1

show abstract

“…23−26 Because of the unique architectures, physical properties, and assembly behaviors, these brush polymers and their BCPs represent a versatile macromolecular platform for a wide range of applications. 1,3,4 Even if we consider only the ones prepared using ROMP of MMs, brush (co)-polymers have already been widely used as soft photonic crystals, 8,21,27 drug delivery vehicles, 28−32 optoelectronic and lithographic materials, 22,33,34 and surface or rheological modifiers. 14,35,36 Synthesis of monofunctional MMs is a critical step toward successful synthesis of brush polymers via ROMP.…”

Section: ■ Introductionmentioning

confidence: 99%

Importance of Macromonomer Quality in the Ring-Opening Metathesis Polymerization of Macromonomers

Teo

Xia

2015

Macromolecules

View full text Add to dashboard Cite

Various macromonomers (MMs) were synthesized using controlled radical polymerization (CRP) by either directly growing from a norbornene-functionalized initiator or chain transfer agent ("direct-growth" or DG method) or coupling a norbornenyl group to preformed polymers ("growth-then-coupling" or GC method). The degree of control for the ring-opening metathesis polymerization (ROMP) of these MMs was found to be dependent on which synthetic method was used for the MMs. Narrowly dispersed brush polymers were consistently obtained from the GC-MMs. In contrast, the DG-MMs resulted in brush polymers with a small high-molecular weight (MW) shoulder or broader molecular weight distribution (MWD). Matrix-assisted laser desorption ionization time-of-flight mass spectrometry of DG-MMs showed the presence of a small amount of α,ω-dinorbornenyl telechelic species resulting from the biradical combination during polymerization. A control study further revealed that even the presence of 1 mol % α,ω-norbornenyl telechelic polymer in the MM resulted in broadening of MWD. Our surprising findings suggest the importance of MM quality and the absence of dinorbornenyl telechelic polymers in achieving the best control for high-MW brush polymers via efficient ROMP of MMs.

show abstract

Synthesis of Isocyanate-Based Brush Block Copolymers and Their Rapid Self-Assembly to Infrared-Reflecting Photonic Crystals

Cited by 218 publications

References 51 publications

Design, Synthesis, and Self-Assembly of Polymers with Tailored Graft Distributions

Design, Synthesis, and Self-Assembly of Polymers with Tailored Graft Distributions

Graft Density Dependence of Main Chain Stiffness in Molecular Rod Brushes

Importance of Macromonomer Quality in the Ring-Opening Metathesis Polymerization of Macromonomers

Contact Info

Product

Resources

About