Skip to main content
NCBI home page
JACS Au logoLink to JACS Au
. 2022 Dec 2;2(12):2800–2808. doi: 10.1021/jacsau.2c00566

Practical Route for Catalytic Ring-Opening Metathesis Polymerization

Indradip Mandal 1, Andreas F M Kilbinger 1,*
PMCID: PMC9795566  PMID: 36590270

Abstract

graphic file with name au2c00566_0008.jpg

Norbornene derivatives are typical monomers for ring-opening metathesis polymerization (ROMP) for synthesizing highly functional polymers. However, the lack of catalytic methods, that is, the lack of readily available chain transfer agents (CTAs) for these monomers has been a significant cost limitation when large-scale syntheses are required. Here, we report commercially available styrene and its derivatives as efficient regioselective CTAs for the catalytic synthesis of metathesis polymers requiring up to 1000 times less ruthenium than in classical ROMP experiments. The molecular weight of the synthesized polymers was controlled by the monomer-to-CTA ratio. Low molecular weight ROMP polymers known for their antimicrobial properties were also synthesized on a gram scale in this report. Polymers were characterized by SEC, 1H NMR spectroscopy, and isotopically resolved MALDI-TOF MS. This approach describes a greener, more cost-effective, and eco-friendly methodology for the preparation of metathesis-based materials on the multigram scale.

Keywords: catalytic ROMP, chain transfer agents, styrene, regioselective metathesis, functional polymers

Introduction

The molecular weight control of polymers is a matter of immense interest as many of the physical and mechanical properties depend on chain length. Well-defined transition-metal-based metathesis catalysts discovered by Grubbs and Schrock allow the synthesis of highly functional and complex ring-opening metathesis polymers1−5 that showed applications in biology/medicinal chemistry,6,7 electronics,8−11 for membranes,12 and many others.13−16 The highly robust and functional group tolerant Grubbs second-generation (G2) and Grubbs third-generation (G3) catalysts are frequently used for polymerizations17,18 to obtain monotelechelic19−25 and heterotelechelic polymers26−29 in a controlled manner. In the conventional ring-opening metathesis polymerization (ROMP), excellent control of the polymer chain length could be achieved using those catalysts (as initiators) in stoichiometric amounts with respect to the number of polymer chains formed. For this reason, it is often challenging to synthesize metathesis-based polymers on a large scale, especially when shorter polymer chains are required. Catalytic methods for the preparation of ROMP polymers have been reported by Grubbs and co-workers using symmetrical chain transfer agents (CTAs).30−32 This method relies on “backbiting” to the polymer backbone to obtain homotelechelic polymers and is limited to very few monomers33 (such as cyclooctene or cyclooctadiene) (Scheme 1). Other methods to synthesize norbornene imide-based ROMP polymers using a sub-stoichiometric amount of ruthenium-based catalysts (Grubbs catalyst or Hoveyda–Grubbs catalyst) include pulsed addition of monomer,34−36 a degenerative reversible chain transfer mechanism (Scheme 1),37,38 or a kinetically controlled catalytic process.39−43 While each of these methods has proven to be helpful to achieve catalytic ROMP, there is no report of any functional, commercial, and inexpensive CTA that can be used to synthesize norbornene imide-based ROMP polymers on a multigram scale at low cost.

Scheme 1. (A,B) Previously Reported CTAs for Metathesis Polymerization with Good Control Over Molecular Weight. (C) New Simple yet Effective CTAs (Styrene and Its Derivatives) for Synthesizing Large-Scale ROMP Polymers.

Scheme 1

Open in a new tab

Herein, we report that styrene and its derivatives, in the presence of 3-bromopyridine, can be used as effective and regioselective CTAs to produce ROMP polymers catalytically via a kinetically controlled chain transfer mechanism. Unlike traditional ROMP polymerization methods, the procedures used in this report are simpler as no Schlenk line conditions were required to carry out the polymerizations.

Results and Discussion

Regioselective Cross-Metathesis

We recently showed that monosubstituted 1,3 diene derivatives could be used as regioselective CTAs in ROMP to produce monotelechelic polymers catalytically.44 The reaction of those derivatives with G3 generates styrene as a side product in a catalytic amount. When we performed the polymerization using a 1,3-diene and G3 in a ratio of 1:1, thus yielding 1 equiv of styrene, we observed a substantial reduction in the molecular weight of the synthesized polymer. We anticipated this could only happen due to chain transfer with styrene during polymerization. Thus, we performed an independent 1H NMR tube reaction mixing styrene (CTA1) (15 equiv) and M1 (see Figure 1) (300 equiv) in chloroform-d. Then, 1 equiv of G3 was added to the NMR tube and the 1H NMR spectrum was recorded immediately. To our surprise, complete consumption of M1 (no triplet peak at 6.25 ppm) and >97% consumption of CTA1 (quartet signal at 6.65 ppm) was observed within the first measurement (<5 min, see Figure S1). SEC analysis of the precipitated polymer (P1) showed an excellent agreement of the observed molecular weight (Mn,SEC(CHCl3) = 4.3 kDa) with that of the theoretical value (Mn,M1/CTA1 = 3.6 kDa). MALDI-TOF MS analysis, on the other hand, showed a major distribution of peaks corresponding to polymer chains with a phenyl group on one end and methylene group on the other, along with two other minor distributions showing a mixture of chain ends (see Figure S2). Surprisingly, the addition of 3-bromopyridine (3BPY) as an additive to the polymerization mixture suppressed the non-regioselective chain transfer completely. A chain end-capping experiment was further performed where a G3-benzylidene initiated poly(exo-N-methyl norbornene imide) (M1:G3 = 20), in the presence of 30 equiv of 3BPY, was terminated with 5 equiv of CTA1 (see Figure S3). A 1H NMR measurement after 10 min showed that the propagating ruthenium carbene signal (G3-alkylidene, 18.55 ppm) had vanished, and a new signal for G3-benzylidene (19.15 ppm) was observed, suggesting a fast and regioselective chain transfer. Besides, this exceptionally fast cross-metathesis with CTA1 could also be observed visually as the deep yellow color of G3-alkylidene immediately changed into green, which is the typical color of G3-benzylidene45 (see Figure S4). Furthermore, 1H NMR spectroscopic data and MALDI-TOF MS analysis of the precipitated polymer (P2) were in agreement with the proposed regioselective chain transfer (see Figures S4 and S5).

Figure 1.

Figure 1

Open in a new tab

Chemical structures of compounds studied here. (a) Structures of CTAs. (b) Structures of monomers. (c) Structures of Ru-catalysts.

Having established the regioselective cross-metathesis of CTA1 with the propagating Ru complex, we explored the applicability of other styrene derivatives. CTA2-6 was commercially available, and CTA7-10 was synthesized in a few straightforward steps (see the Supporting Information). CTA2 was then utilized in a one-pot catalytic polymerization maintaining the ratio of G3:3BPY:CTA2:M1 = 1:30:50:500. SEC analysis of the resulting polymer revealed a monomodal distribution with the molecular weight as determined by the M1:CTA2 ratio (P4, Mn,M1/CTA2 = 1.9 kDa vs Mn,SEC(CHCl3) = 2.8 kDa) and a dispersity of 1.84 suggesting a kinetically controlled mechanism (Figure 2). Different ratios of M1:CTA2 were further investigated, and the resulting polymers showed a linear dependence between the number average molecular weight (determined by SEC in CHCl3) and the monomer to CTA2 ratio (see Figure 3A). Unlike the conventional ROMP mechanism, in a catalytic ROMP, incomplete initiation of the Ru complex does not influence the target molecular weight of the polymers. Therefore, we used the cheaper and more stable G2 and the Hoveyda–Grubbs catalyst (HG-II) to perform a polymerization under similar conditions. 1H NMR tube polymerization reactions using CTA2 and M1 with either G2 or HG-II produced polymers P8 (Mn,SEC(CHCl3) = 2.5 kDa with G2) and P9 (Mn,SEC(CHCl3) = 2.4 kDa with HG-II) with excellent control over the molecular weight (see Table 1 and Figures S8 and S9). Next, CTA3 was used under similar polymerization conditions with M1 (P10, G3:CTA3 = 1:100, Mn,SEC(CHCl3) = 5.3 kDa, Figure 5A) and M3 (P11, HG-II:CTA3 = 1:20, Mn,SEC(CHCl3) = 5.0 kDa) and CTA4 was used with M3 (P12, HG-II:CTA4 = 1:100, Mn,SEC(CHCl3) = 8.5 kDa) to produce monotelechelic polymers catalytically. The purified polymers were fully characterized using 1H NMR spectroscopy and MALDI-TOF MS (see the Supporting Information).

Figure 2.

Figure 2

Open in a new tab

Mechanism for catalytic ROMP. First, the G3/G2/HG-II catalyst reacts with CTAs regioselectively in the presence of 3BPY. The functionalized catalyst reacts with monomer (here only M1 is shown as an example) to form the propagating species, which reacts regioselectively with styrene derivatives to give back the functional catalyst closing the catalytic cycle.

Figure 3.

Figure 3

Open in a new tab

(A) Plot of the number average molecular weight (Mn, measured by SEC in CHCl3) vs the monomer (M1) to CTA (CTA2) ratio shows a linear correlation. The polymerizations were carried out using a constant ratio of G3:3BPY:CTA2 = 1:30:50 and varying M1 accordingly. (B) Plot of monomer (M1) and CTA5 conversion with time as determined by 1H NMR spectroscopy (CD2Cl2, 400 MHz) showing both were consumed with almost the same proportion throughout the polymerization. (C) In the same experiment, a plot of consumption of M1 vs consumption of CTA5 showed a linear relationship, further proving a kinetically controlled chain transfer mechanism. (D) Final proof for the kinetically controlled mechanism given by SEC measurements showed an almost constant Mn value over the whole polymerization time.

Table 1. Catalytic Polymerization Data Using Functional Styrene Derivatives as CTAs.

polymer catalyst (Cat) CTA monomer (M) Cat/CTA/Ma Mn (non-catalytic, M/Cat) kDa Mn,theoretical(catalytic, M/CTA) kDa Mn,observed (SEC, CHCl3)b kDa dispersity (D̵)
P3 G3 CTA1 M1 1:5:60 10.7 2.2 2.6 1.71
P4 G3 CTA2 M1 1:50:500 88.5 1.9 2.8 1.84
P8 G2 CTA2 M1 1:20:200 35.4 1.9 2.5 2.20
P9 HG-II CTA2 M1 1:20:200 35.4 1.9 2.4 2.15
P10 G3 CTA3 M1 1:100:2000 354 3.7 5.3 2.05
P12 HG-II CTA4 M3 1:100:2000 569 5.8 8.5 2.07
P13 G3 CTA5 M1 1:20:200 35.5 1.9 3.0 1.86
P14 G3 CTA5 M1 1:20:1200 212.4 11 14.5 1.96
P15 G2 CTA6 M1 1:100:2000 569 6.0 7.0 1.72
P16 G3 CTA7 M1 1:100:3000 531 5.5 8.1 1.95
P17 HG-II CTA8 M1 1:20:200 35.4 1.9 3.5 2.22
P18 HG-II CTA8 M1 1:150:4500 797 5.6 10 2.10
P19 G3 CTA9 M1 1:20:200 35.6 1.9 3.0 2.00
P20 HG-II CTA10 M1 1:20:200 35.4 1.9 3.0 1.93
P21 G2 CTA6 M2 1:200:6000 564 2.9 20 2.20
P22 HG-II CTA1 M1 1:500:5000 900 1.8 3.0 1.72
P23 HG-II CTA1 M1 1:1000:15,000 2655 2.7 4.0 1.80
P29 G2 CTA11 M1 1:20:400 71 3.7 5.4 1.96
P30 G2 CTA12 M1 1:20:400 71 3.7 4.9 2.08
Open in a new tab
a

3-Bromopyridine (3BPY) was used (typically 30 equiv) as an additive in the polymerization.

b

SEC (CHCl3) was calibrated against poly(styrene) standards.

Figure 5.

Figure 5

Open in a new tab

Isotopically resolved MALDI-TOF mass spectrum (DCTB, AgTFA/NaTFA) of the synthesized polymer (A) P10, (B) P24, (C) P25, and (D) P26 matching the expected end groups. The zoomed mono-isotopic distributions (black lines) were compared with the simulated (red lines) spectrum in each case, providing a good agreement between the experimentally observed and the simulated mass distributions.

Kinetic and Mechanistic Studies

To elucidate the proposed kinetically controlled mechanism (see Figure 2), we performed a 1H NMR kinetic analysis using M1, CTA5, and G3. The reagents were mixed in a ratio of 200:20:1, respectively, and the consumption of both, CTA5 and M1, was followed by 1H NMR spectroscopy over time. As expected for a kinetically controlled mechanism, both reagents were consumed proportionately over the entire polymerization time (see Figure 3B).

Additionally, a plot of monomer versus CTA5 consumption (see Figure 3C) showed a linear relationship, which should be the case for a kinetically controlled chain transfer polymerization. Further proof of the mechanism was obtained by following the polymerization (G3:3BPY:CTA5:M1 = 1:30:40:2000) by SEC (via quenching aliquots at a different time intervals, Figure 3D) over time. An almost constant number average molecular weight (Mn = 12 kDa) was obtained over 1320 min suggesting that both, the rate of propagation and the rate of chain transfer with the CTA were similar, supporting once more a kinetically controlled mechanism. The exceptionally high rate of chain transfer and regioselectivity of styrene derivatives was unexpected because styrene has been utilized numerous times in the literature as a cross-metathesis partner or even in self-metathesis to produce stilbene derivatives.45−48 We believe that in the presence of 3BPY, the reactivity of the Ru–carbene complex is suppressed to a great extent,49 thus making it more selective to form Ru–benzylidene, which has kinetic and thermodynamic preferences over Ru–methylidene.50 It is noteworthy that in the SEC trace (see Figure 3D), even after 1320 min, no higher molecular weight shoulder peak was observed as the elugram maintained its monomodal distribution suggesting that no chain end coupled product was formed by the removal of ethylene. Furthermore, a detailed kinetic analysis was performed using 1H NMR spectroscopy to determine the rate constants for the consumption of both CTA and monomer during the kinetically controlled polymerization (see Figures S24–S28). Unlike our previous report,44 here, the rate constant for the consumption of CTA2 was 1.53 times less than that of the monomer indicating a lower chain transfer rate constant in the case of styrenes compared to monosubstituted 1,3 dienes. Moreover, rate constants for both the chain transfer event and monomer propagation were determined using the Mayo equation.51,52 A plot of 1/DP (DP = degree of polymerization) versus CTA to monomer concentrations produced a linear relationship indicating that efficient chain transfer was involved (Figure S29). Additional kinetic information showed that the ratio of monomer propagation constant to chain transfer constant was 1.68 which, again suggesting that the rate constants of monomer propagation and chain transfer are of almost similar magnitude. This criterion should be fulfilled to achieve control over the molar mass of the polymers synthesized via a kinetically controlled chain transfer process. Our present study clearly shows a kinetically controlled chain transfer mechanism allowing us to obtain good to excellent control over the molecular weight of the synthesized polymers (see Table 1).

Functional Catalytic ROMP

M1 was further used to synthesize a library of highly end-functional ROMP polymers, maintaining a high CTA:Ru complex ratio. For instance, P15 (G2:CTA6 = 1:100, Mn,SEC(CHCl3) = 7.0 kDa), P16 (G3:CTA7 = 1:100, Mn,SEC(CHCl3) = 8.1 kDa), and P18 (HG-II:CTA8 = 1:150, Mn,SEC(CHCl3) = 10.0 kDa) (see Table 1) were synthesized under non-Schlenk conditions carrying an atom transfer radical polymerization initiator, a Boc-protected aromatic amine, or a DMB-protected aromatic acid group at one chain end. Both P16 and P18 were further deprotected using trifluoroacetic acid to give the free amine (P24) and acid functional (P25) ROMP polymers on a gram scale using at least 100 times less Grubbs catalyst than in a standard ROMP polymerization. These polymers were fully characterized by 1H NMR spectroscopy (see the Supporting Information) and MALDI-TOF MS (see Figure 5B,C). Benzylic alcohol functional CTA10 was also utilized effectively using HG-II and M1 to produce P20. The presence of the alcohol group was confirmed via MALDI-TOF MS. When a more reactive monomer, M2, was employed in our method using CTA6, poor control over molecular weight was observed (Mn,M3/CTA6 = 2.9 kDa vs Mn,SEC(CHCl3) = 20.0 kDa). Nonetheless, the molecular weight calculated by the monomer to initiator ratio (assuming no chain transfer with CTA6) would have been as high as 564 kDa. A polymer of Mn = 20 kDa was obtained suggesting a substantial degree of chain transfer was involved.

Our recent study44 revealed that electron-rich CTAs are more suitable for catalytic ROMP, probably, due to higher chain transfer rates of Ru–carbene complexes in the case of electron-rich olefins. To illustrate the versatility of our method, we chose to test the applicability of highly electron deficient styrenes in our system. CTA11 and CTA12, containing a nitro group and a cyano group at the para position, respectively, were studied using 1H NMR spectroscopy. In both cases, almost full consumption of monomer (>95%) was observed, whereas the CTA consumption was around 85%. It means even electron deficient styrenes could be used in our catalytic system (see Figure 4). Gratifyingly, these CTAs maintained same kind of regioselective chain transfer as observed before, as only one type of mass distribution was detected in MALDI-TOF mass spectra of the polymers (see Figures S94 and S95).

Figure 4.

Figure 4

Open in a new tab

Controlled catalytic ROMP with highly electron-withdrawing CTAs.

Slow monomer, such as, endo-MNI (endo-M1) was also studied for our catalytic ROMP. We found that due to slow reactivity of the endo isomer, catalyst decomposition competes with the propagation and chain transfer events, resulting in very low monomer conversion (35%) in our standard reaction conditions (Figure S21). When, the same polymerization was performed without 3BPY, full consumption of both CTA and monomer was observed (Figure S22), but MALDI-TOF MS showed mixture of chain ends indicating that non-regioselective chain transfer was involved (Figure S23).

Our catalytic ROMP method is ideal for synthesizing low molecular weight polymers as their established synthesis requires a very high loading of costly and toxic transition metal–carbene complex. This limits the application of those polymers where metal contamination could play a critical role. In 2008, the Tew group showed that oligomers of an oxanorbornene monomer (M4) could be used as potential antimicrobial ROMP polymers that have a very high selectivity toward bacteria cells over mammalian cells.53 The molecular weight of the synthesized oligomers proved to be an essential parameter in determining the selectivity. Only very short oligomers (degree of polymerization = 8) prevented further growth of bacteria cells and showed the essential selectivity. Due to the lack of any suitable CTAs, those antimicrobial ROMP polymers could only be synthesized on the milligram scale using a very high loading of the Grubbs initiator. Here, we were able to synthesize an oligomer of M4 (P27, Mn,SEC(CHCl3) = 2.8 kDa) on a 1.3 g scale using only 0.07 mol % of the HG-II catalyst (150 times less than previously reported) to exemplify the potential of our method. The high chain-end fidelity of P27 was established by 1H NMR spectroscopic and MALDI-TOF MS data (see Figures S74 and S93). Further deprotection using trifluoroacetic acid produced P28 having the same backbone functionality (cationic amphiphilic groups) as shown by Tew et al. This methodology could further be explored in synthesizing many biologically useful functional ROMP polymers where high loading of toxic ruthenium metal has so far limited the applicability.

Robust Catalytic ROMP

The mechanism of our catalytic method suggests that the resting state of the catalyst after chain transfer with a CTA is a Ru–benzylidene complex. This was also observed in the 1H NMR kinetics experiment (see Figures S8–S13). We, therefore, exploited the high stability of the benzylidene complex by showing that even technical grade dichloromethane could be used as a solvent, and the polymerization could be performed under non-degassed conditions in an open Erlenmeyer flask (see Figure S16). A ratio of G2:3BPY:CTA6:M1 = 1:30:200:10,000 was used to obtain polymer P26 (Mn,SEC(CHCl3) = 11.5 kDa) with 90% yield. MALDI-TOF analysis further proved the anticipated polymeric species (see Figure 5D).

Encouraged by the unusual robustness of our system, we focused on polymerization conditions using even less Ru initiator. When G2 was used as a catalyst using CTA1 and M1, a catalytic polymerization using 500 times less Ru initiator than required classically resulted in very low monomer conversion (<10%) even with extended reaction time.

A higher monomer concentration increased the conversion to only 35% after 48 h of reaction time (see Table S2). When HG-II was used instead of G2, a reasonable monomer conversion (90%) was achieved within 20 h along with a controlled polymerization (HG-II:CTA1 = 1:500, P22, Mn,SEC(CHCl3) = 3.0 kDa). This could be attributed to the known higher turnover number for HG-II over G2.54 Having successfully carried out catalytic polymerization using 500 times less Ru initiator than typically required, we aimed for lowering the catalyst to 1/1000 of the usual amount. Thus, P23 was synthesized (HG-II:CTA1:M1 = 1:1000:15,000, Mn,SEC(CHCl3) = 4.0 kDa) with a monomer conversion of 85%. P23 was fully characterized by 1H NMR spectroscopy and MALDI-TOF MS and showed the expected end groups. This is to date the lowest reported catalytic ROMP polymerization to synthesize norbornene imide-based metathesis polymers.

Conclusions

In conclusion, we have successfully developed a simple yet highly robust polymerization method to prepare ROMP polymers catalytically under non-degassed conditions using commercially available and inexpensive styrenes as CTAs. Telechelic polymers with functional groups such as aldehyde, atom transfer radical polymerization initiator (benzyl chloride), aromatic amine, aromatic acid, nitro, cyano, and primary alcohol were synthesized using a catalytic amount of costly and toxic metathesis-based catalysts. Antimicrobial ROMP polymers that were previously shown to be very effective against specific bacteria could be prepared on the gram scale with our method. In this report, the catalyst to CTA ratio examined was as low as 1:1000, which simply means a 1000-fold saving of expensive ruthenium–metal complex. Ring-opening metathesis polymerization offers access to a pool of highly functional and valuable materials for many different disciplines. The limiting factor regarding the synthesis of those materials appears to be the stoichiometric use of expensive metathesis catalysts. Our newly discovered CTAs based on styrene and its derivatives could overcome this limitation.

Methods

Catalytic ROMP was performed at room temperature using dry dichloromethane (non-degassed) as the solvent. A typical procedure (reaction equivalents are given for the synthesis of polymer P18) is as follows: in a round-bottom flask equipped with a magnetic stirrer bar, M1 (4500 equiv, 2.5 g) was added followed by the addition of 25 mL of dichloromethane. In a vial, 3BPY (30 equiv, 15 mg) and CTA8 (150 equiv, 143 mg) were dissolved in 3 mL of dichloromethane and added to the flask. To this stirred mixture, HG-II (1 equiv, 2 mg) dissolved in 0.5 mL dichloromethane was added (to give a final concentration of 0.5 M with respect to M1), and the flask was capped with a rubber septum and stirred at room temperature until all the monomer was consumed (monitored by 1H NMR spectroscopy). Then, few drops of ethyl vinyl ether were added. The solvent was removed by rotary evaporation, and the crude polymer was precipitated once from cold methanol (150 mL) to obtain a colorless solid with a yield of 91%.

Acknowledgments

A.F.M.K. and I.M. thank the Swiss National Science Foundation (grant number: 200020_182059/1) for funding.

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacsau.2c00566.

  • Instrument’s data, experimental methods, NMR data, MALDI-TOF data, and SEC data (PDF)

Author Contributions

All authors have given approval to the final version of the manuscript.

The authors declare no competing financial interest.

Supplementary Material

au2c00566_si_001.pdf (13.8MB, pdf)

References

  1. Sutthasupa S.; Shiotsuki M.; Sanda F. Recent Advances in Ring-Opening Metathesis Polymerization, and Application to Synthesis of Functional Materials. Polym. J. 2010, 42, 905–915. 10.1038/pj.2010.94. [DOI] [Google Scholar]
  2. Martinez H.; Ren N.; Matta M. E.; Hillmyer M. A. Ring-Opening Metathesis Polymerization of 8-Membered Cyclic Olefins. Polym. Chem. 2014, 5, 3507. 10.1039/c3py01787g. [DOI] [Google Scholar]
  3. Wang H.; Onbulak S.; Weigand S.; Bates F. S.; Hillmyer M. A. Polyolefin Graft Copolymers through a Ring-Opening Metathesis Grafting through Approach. Polym. Chem. 2021, 12, 2075–2083. 10.1039/d0py01728k. [DOI] [Google Scholar]
  4. Peterson G. I.; Choi T.-L. Cascade Polymerizations: Recent Developments in the Formation of Polymer Repeat Units by Cascade Reactions. Chem. Sci. 2020, 11, 4843–4854. 10.1039/d0sc01475c. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Bang K.; Choi T. Synthesis of Well-Defined Poly(norbornene) Containing Carbon Nanodots by Controlled ROMP. J. Polym. Sci. 2020, 58, 48–51. 10.1002/pola.29506. [DOI] [Google Scholar]
  6. Smith D.; Pentzer E. B.; Nguyen S. T. Bioactive and Therapeutic ROMP Polymers. Polym. Rev. 2007, 47, 419–459. 10.1080/15583720701455186. [DOI] [Google Scholar]
  7. Sarapas J. M.; Backlund C. M.; deRonde B. M.; Minter L. M.; Tew G. N. ROMP- and RAFT-Based Guanidinium-Containing Polymers as Scaffolds for Protein Mimic Synthesis. Chem.—Eur. J. 2017, 23, 6858–6863. 10.1002/chem.201700423. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Kang C.; Park H.; Lee J.-K.; Choi T.-L. Cascade Polymerization via Controlled Tandem Olefin Metathesis/Metallotropic 1,3-Shift Reactions for the Synthesis of Fully Conjugated Polyenynes. J. Am. Chem. Soc. 2017, 139, 11309–11312. 10.1021/jacs.7b04913. [DOI] [PubMed] [Google Scholar]
  9. Yang S.; Shin S.; Choi I.; Lee J.; Choi T.-L. Direct Formation of Large-Area 2D Nanosheets from Fluorescent Semiconducting Homopolymer with Orthorhombic Crystalline Orientation. J. Am. Chem. Soc. 2017, 139, 3082–3088. 10.1021/jacs.6b12378. [DOI] [PubMed] [Google Scholar]
  10. Peterson G. I.; Yang S.; Choi T. L. Synthesis of Functional Polyacetylenes via Cyclopolymerization of Diyne Monomers with Grubbs-Type Catalysts. Acc. Chem. Res. 2019, 52, 994–1005. 10.1021/acs.accounts.8b00594. [DOI] [PubMed] [Google Scholar]
  11. Kang C.; Jung K.; Ahn S.; Choi T. L. Controlled Cyclopolymerization of 1,5-Hexadiynes to Give Narrow Band Gap Conjugated Polyacetylenes Containing Highly Strained Cyclobutenes. J. Am. Chem. Soc. 2020, 142, 17140–17146. 10.1021/jacs.0c07666. [DOI] [PubMed] [Google Scholar]
  12. Zha Y.; Disabb-Miller M. L.; Johnson Z. D.; Hickner M. A.; Tew G. N. Metal-Cation-Based Anion Exchange Membranes. J. Am. Chem. Soc. 2012, 134, 4493–4496. 10.1021/ja211365r. [DOI] [PubMed] [Google Scholar]
  13. Chen Y.; Abdellatif M. M.; Nomura K. Olefin Metathesis Polymerization: Some Recent Developments in the Precise Polymerizations for Synthesis of Advanced Materials (by ROMP, ADMET). Tetrahedron 2018, 74, 619–643. 10.1016/j.tet.2017.12.041. [DOI] [Google Scholar]
  14. Yang J.; Horst M.; Werby S. H.; Cegelski L.; Burns N. Z.; Xia Y. Bicyclohexene-peri-naphthalenes: Scalable Synthesis, Diverse Functionalization, Efficient Polymerization, and Facile Mechanoactivation of Their Polymers. J. Am. Chem. Soc. 2020, 142, 14619–14626. 10.1021/jacs.0c06454. [DOI] [PubMed] [Google Scholar]
  15. Elling B. R.; Su J. K.; Xia Y. Polymerization of Cyclopropenes: Taming the Strain for the Synthesis of Controlled and Sequence-Regulated Polymers. Acc. Chem. Res. 2021, 54, 356–365. 10.1021/acs.accounts.0c00638. [DOI] [PubMed] [Google Scholar]
  16. Yang J.; Xia Y. Mechanochemical Generation of Acid-Degradable Poly(Enol Ether)S. Chem. Sci. 2021, 12, 4389–4394. 10.1039/d1sc00001b. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Sanford M. S.; Love J. A.; Grubbs R. H. Mechanism and Activity of Ruthenium Olefin Metathesis Catalysts. J. Am. Chem. Soc. 2001, 123, 6543–6554. 10.1021/ja010624k. [DOI] [PubMed] [Google Scholar]
  18. Choi T. L.; Grubbs R. H. Controlled Living Ring-Opening-Metathesis Polymerization by a Fast-Initiating Ruthenium Catalyst. Angew. Chem., Int. Ed. 2003, 42, 1743–1746. 10.1002/anie.200250632. [DOI] [PubMed] [Google Scholar]
  19. Matson J. B.; Grubbs R. H. Monotelechelic Poly(Oxa)Norbornenes by Ring-Opening Metathesis Polymerization Using Direct End-Capping and Cross-Metathesis. Macromolecules 2010, 43, 213–221. 10.1021/ma9019366. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Hilf S.; Grubbs R. H.; Kilbinger A. F. M. End Capping Ring-Opening Olefin Metathesis Polymerization Polymers with Vinyl Lactones. J. Am. Chem. Soc. 2008, 130, 11040–11048. 10.1021/ja8022863. [DOI] [PubMed] [Google Scholar]
  21. Hilf S.; Grubbs R. H.; Kilbinger A. F. M. Sacrificial Synthesis of Hydroxy-Functionalized ROMP Polymers: An Efficiency Study. Macromolecules 2008, 41, 6006–6011. 10.1021/ma801098q. [DOI] [Google Scholar]
  22. Nagarkar A. A.; Crochet A.; Fromm K. M.; Kilbinger A. F. M. Efficient Amine End-Functionalization of Living Ring-Opening Metathesis Polymers. Macromolecules 2012, 45, 4447–4453. 10.1021/ma300602p. [DOI] [Google Scholar]
  23. Hilf S.; Kilbinger A. F. M. Thiol-Functionalized ROMP Polymers via Sacrificial Synthesis. Macromolecules 2009, 42, 4127–4133. 10.1021/ma900036c. [DOI] [Google Scholar]
  24. Nagarkar A. A.; Kilbinger A. F. M. End Functional ROMP Polymers via Degradation of a Ruthenium Fischer Type Carbene. Chem. Sci. 2014, 5, 4687–4692. 10.1039/c4sc02242d. [DOI] [Google Scholar]
  25. Fu L.; Zhang T.; Fu G.; Gutekunst W. R. Relay Conjugation of Living Metathesis Polymers. J. Am. Chem. Soc. 2018, 140, 12181–12188. 10.1021/jacs.8b07315. [DOI] [PubMed] [Google Scholar]
  26. Pal S.; Lucarini F.; Ruggi A.; Kilbinger A. F. M. Functional Metathesis Catalyst Through Ring Closing Enyne Metathesis: One Pot Protocol for Living Heterotelechelic Polymers. J. Am. Chem. Soc. 2018, 140, 3181–3185. 10.1021/jacs.7b12805. [DOI] [PubMed] [Google Scholar]
  27. Zhang T.; Fu L.; Gutekunst W. R. Practical Synthesis of Functional Metathesis Initiators Using Enynes. Macromolecules 2018, 51, 6497–6503. 10.1021/acs.macromol.8b00866. [DOI] [Google Scholar]
  28. Mandal A.; Mandal I.; Kilbinger A. F. M. One-Pot Heterotelechelic Metathesis Polymers via Regioselective Chain Transfer Agents. ACS Macro Lett. 2021, 10, 1487–1492. 10.1021/acsmacrolett.1c00613. [DOI] [PubMed] [Google Scholar]
  29. Kilbinger A. F. M. Functional End Groups in Living Ring-Opening Metathesis Polymerization. Synlett 2019, 30, 2051–2057. 10.1055/s-0039-1690154. [DOI] [Google Scholar]
  30. Hillmyer M. A.; Grubbs R. H. Chain Transfer in the Ring-Opening Metathesis Polymerization of Cyclooctadiene Using Discrete Metal Alkylidenes. Macromolecules 1995, 28, 8662–8667. 10.1021/ma00129a027. [DOI] [Google Scholar]
  31. Hillmyer M. A.; Nguyen S. T.; Grubbs R. H. Utility of a Ruthenium Metathesis Catalyst for the Preparation of End-Functionalized Polybutadiene. Macromolecules 1997, 30, 718–721. 10.1021/ma961316n. [DOI] [Google Scholar]
  32. Bielawski C. W.; Benitez D.; Morita T.; Grubbs R. H. Synthesis of End-Functionalized Poly(norbornene)s via Ring-Opening Metathesis Polymerization. Macromolecules 2001, 34, 8610–8618. 10.1021/ma010878q. [DOI] [Google Scholar]
  33. Michel X.; Fouquay S.; Michaud G.; Simon F.; Brusson J.-M.; Carpentier J.-F.; Guillaume S. M. α,ω-Bis(trialkoxysilyl) difunctionalized polycyclooctenes from ruthenium-catalyzed chain-transfer ring-opening metathesis polymerization. Polym. Chem. 2016, 7, 4810–4823. 10.1039/c6py00849f. [DOI] [Google Scholar]
  34. Matson J. B.; Virgil S. C.; Grubbs R. H. Pulsed-Addition Ring-Opening Metathesis Polymerization: Catalyst-Economical Syntheses of Homopolymers and Block Copolymers. J. Am. Chem. Soc. 2009, 131, 3355–3362. 10.1021/ja809081h. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Zhang T.; Gutekunst W. R. Pulsed-Addition Ring-Opening Metathesis Polymerization with Functional Enyne Reagents. Polym. Chem. 2020, 11, 259–264. 10.1039/c9py00965e. [DOI] [Google Scholar]
  36. Mandal A.; Mandal I.; Kilbinger A. F. M. Pulsed-Addition ROMP: Catalytic Syntheses of Heterotelechelic Polymers via Regioselective Chain Transfer Agents. ACS Macro Lett. 2022, 11, 491–497. 10.1021/acsmacrolett.2c00094. [DOI] [PubMed] [Google Scholar]
  37. Yasir M.; Liu P.; Tennie I. K.; Kilbinger A. F. M. Catalytic living ring-opening metathesis polymerization with Grubbs’ second- and third-generation catalysts. Nat. Chem. 2019, 11, 488–494. 10.1038/s41557-019-0239-4. [DOI] [PubMed] [Google Scholar]
  38. Liu P.; Yasir M.; Kilbinger A. F. M. Catalytic Living Ring Opening Metathesis Polymerisation: The Importance of Ring Strain in Chain Transfer Agents. Angew. Chem., Int. Ed. 2019, 58, 15278–15282. 10.1002/anie.201907921. [DOI] [PubMed] [Google Scholar]
  39. Katayama H.; Urushima H.; Ozawa F. Ring-Opening Metathesis Polymerization of Norbornene in the Presence of Heteroatom-Substituted Vinylic Compounds: Highly Selective Synthesis of End-Functionalized Poly(Norbornene)S. Chem. Lett. 1999, 28, 369–370. 10.1246/cl.1999.369. [DOI] [Google Scholar]
  40. Katayama H.; Yonezawa F.; Nagao M.; Ozawa F. Ring-Opening Metathesis Polymerization of Norbornene Using Vinylic Ethers as Chain-Transfer Agents: Highly Selective Synthesis of Monofunctional Macroinitiators for Atom Transfer Radical Polymerization. Macromolecules 2002, 35, 1133–1136. 10.1021/ma0110249. [DOI] [Google Scholar]
  41. Liu P.; Yasir M.; Ruggi A.; Kilbinger A. F. M. Heterotelechelic Polymers by Ring-Opening Metathesis and Regioselective Chain Transfer. Angew. Chem. 2018, 130, 926–929. 10.1002/ange.201708733. [DOI] [PubMed] [Google Scholar]
  42. Mandal A.; Mandal I.; Kilbinger A. F. M. Catalytic Syntheses of Degradable Polymers via Ring-Opening Metathesis Copolymerization Using Vinyl Ethers as Chain Transfer Agents. Macromolecules 2022, 55, 7827–7833. 10.1021/acs.macromol.2c01373. [DOI] [Google Scholar]
  43. Suslick B. A.; Alzate-Sanchez D. M.; Moore J. S. Scalable Frontal Oligomerization: Insights from Advanced Mass Analysis. Macromolecules 2022, 55, 8234–8241. 10.1021/acs.macromol.2c01654. [DOI] [Google Scholar]
  44. Mandal I.; Mandal A.; Rahman M. A.; Kilbinger A. F. M. Chain Transfer Agents for the Catalytic Ring Opening Metathesis Polymerization of Norbornenes. Chem. Sci. 2022, 13, 12469–12478. 10.1039/d2sc04078f. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Schwab P.; Grubbs R. H.; Ziller J. W. Synthesis and Applications of RuCl2(CHR’)(PR3)2: The Influence of the Alkylidene Moiety on Metathesis Activity. J. Am. Chem. Soc. 1996, 118, 100–110. 10.1021/ja952676d. [DOI] [Google Scholar]
  46. Pietraszuk C.; Marciniec B.; Fischer H. Cross-Metathesis of Vinylsilanes with Styrene Catalyzed by Ruthenium–Carbene Complexes. Organometallics 2000, 19, 913–917. 10.1021/om9909901. [DOI] [Google Scholar]
  47. Jana A.; Zieliński G. K.; Czarnocka-Śniadała S.; Grudzień K.; Podwysocka D.; Szulc M.; Kajetanowicz A.; Grela K. Synthesis of Substituted β-Functionalised Styrenes by Microwave-Assisted Olefin Cross-Metathesis and Scalable Synthesis of Apremilast. ChemCatChem 2019, 11, 5808–5813. 10.1002/cctc.201901473. [DOI] [Google Scholar]
  48. Chatterjee A. K.; Toste F. D.; Choi T.-L.; Grubbs R. H. Ruthenium-Catalyzed Olefin Cross Metathesis of Styrenes as an Alternative to the Heck and Cross-Coupling Reactions. Adv. Synth. Catal. 2002, 344, 634.. [DOI] [Google Scholar]
  49. Elling B. R.; Su J. K.; Feist J. D.; Xia Y. Precise Placement of Single Monomer Units in Living Ring-Opening Metathesis Polymerization. Chem 2019, 5, 2691–2701. 10.1016/j.chempr.2019.07.017. [DOI] [Google Scholar]
  50. Vougioukalakis G. C.; Grubbs R. H. Ruthenium-Based Heterocyclic Carbene-Coordinated Olefin Metathesis Catalysts. Chem. Rev. 2010, 110, 1746–1787. 10.1021/cr9002424. [DOI] [PubMed] [Google Scholar]
  51. Mayo F. R. Chain Transfer in the Polymerization of Styrene: The Reaction of Solvents with Free Radicals1. J. Am. Chem. Soc. 1943, 65, 2324–2329. 10.1021/ja01252a021. [DOI] [Google Scholar]
  52. Hyatt M. G.; Guironnet D. Silane as Chain Transfer Agent for the Polymerization of Ethylene Catalyzed by a Palladium(II) Diimine Catalyst. ACS Catal. 2017, 7, 5717–5720. 10.1021/acscatal.7b01299. [DOI] [Google Scholar]
  53. Lienkamp K.; Madkour A. E.; Musante A.; Nelson C. F.; Nüsslein K.; Tew G. N. Antimicrobial Polymers Prepared by ROMP with Unprecedented Selectivity: A Molecular Construction Kit Approach. J. Am. Chem. Soc. 2008, 130, 9836–9843. 10.1021/ja801662y. [DOI] [PMC free article] [PubMed] [Google Scholar]
  54. Maechling S.; Zaja M.; Blechert S. Unexpected Results of a Turnover Number (TON) Study Utilising Ruthenium-Based Olefin Metathesis Catalysts. Adv. Synth. Catal. 2005, 347, 1413–1422. 10.1002/adsc.200505053. [DOI] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

au2c00566_si_001.pdf (13.8MB, pdf)

Articles from JACS Au are provided here courtesy of American Chemical Society

RESOURCES