Center for Sustainable Polymers (CSP)

Persistent link for this communityhttps://hdl.handle.net/11299/193178

The mission of the Center for Sustainable Polymers (CSP) is to transform how plastics are made and unmade through innovative research, engaging education, and diverse partnerships that together foster environmental stewardship. CSP participants aim to design, prepare, and implement polymers derived from renewable resources for a wide range of advanced applications, and to promote future economic development, energy efficiency, and environmental sustainability in the emergent area of biobased products.

https://csp.umn.edu

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Supporting Data for “Renewable, Degradable, and Chemically Recyclable Cross-Linked Elastomers”
(2017-05-18) Hillmyer, Marc A; Brutman, Jacob P; De Hoe, Guilhem X; Schneiderman, Deborah K; Le, Truyen, N; hillmyer@umn.edu; Hillmyer, Marc A
These files contain data along with associated output from instrumentation supporting all results reported in Jacob P. Brutman, Guilhem X. De Hoe, Deborah K. Schneiderman, Truyen N. Le, and Marc A. Hilmyer Renewable, Degradable, and Chemically Recyclable Cross-Linked Elastomers. Industrial & Engineering Chemistry Research 2016 55 (42), 11097-11106. In Brutman et. al. we found: Most commercial elastomers, typified by vulcanized natural rubber, are cross-linked polymers and as such cannot easily be reprocessed or recycled. While some are derived from renewable resources, the majority are produced from petroleum feedstocks and do not easily degrade. In this study, renewable elastomers based on β-methyl-δ-valerolactone were produced using two different methodologies: (1) tandem copolymerization/cross-linking with a bis(six-membered cyclic carbonate); (2) cross-linking of a linear poly(β-methyl-δ-valerolactone) homopolymer with a free-radical generator. The mechanical properties of these materials were investigated; tensile strengths of up to 12 MPa and elongations of up to 2000% were observed. Inclusion of a filler (fumed silica) was used to enhance the performance of the elastomers without significant loss of elasticity, with some composites exhibiting tensile strengths nearly double that of the neat elastomer. Aqueous degradation studies indicated that the materials were capable of degradation in acidic and basic conditions at 60 °C. Moreover, these cross-linked elastomers can also be chemically recycled, yielding monomer in high purity and yield (>91% and 93%, respectively).
Supporting Data for “Why So Slow? Mechanistic Insights from Studies of a Poor Catalyst for Polymerization of ε-Caprolactone”
(2017-05-18) Tolman, William, B; Cramer, Christopher, J; Stasiw, Daniel E; Mandal, Mukunda; Neisen, Benjamin D; Mitchell, Lauren A; wtolman@umn.edu; Tolman, William, B.
These files contain data along with associated output from instrumentation supporting all results reported in Stasiw, D. E.; Mandal, M.; Neisen, B. D.; Mitchell, L. A.; Cramer, C. J.; Tolman, W. B. Why so slow? Mechanistic insights from studies of a poor catalyst for polymerization of ε-caprolactone. Inorg. Chem., 2016, 56, 725–728. Polymerization of ε-caprolactone (CL) using an aluminum alkoxide catalyst (1) designed to prevent unproductive trans binding was monitored at 110 °C in toluene-d8 by 1H NMR and the concentration versus time data fit to a first-order rate expression. A comparison of t1/2 for 1 to values for many other aluminum alkyl and alkoxide complexes shows much lower activity of 1 toward polymerization of CL. Density functional theory calculations were used to understand the basis for the slow kinetics. The optimized geometry of the ligand framework of 1 was found indeed to make CL trans binding difficult: no trans-bound intermediate could be identified as a local minimum. Nor were local minima for cis-bound precomplexes found, suggesting a concerted coordination–insertion for polymer initiation and propagation. The sluggish performance of 1 is attributed to a high-framework distortion energy required to deform the “resting” ligand geometry to that providing optimal catalysis in the corresponding transition-state structure geometry, thus suggesting a need to incorporate ligand flexibility in the design of efficient polymerization catalysts.. Corresponding author for experimental data is William B. Tolman (wtolman@umn.edu). Corresponding author for computational data is Christopher J. Cramer (cramer@umn.edu).
Supporting Data for “Engineering of a Highly Efficient Escherichia coli Strain for Mevalonate Fermentation through Chromosomal Integration”
(2017-05-18) Zhang, Kechun; Wang, Jilong; Niyompanich, Suthamat; Tai, Yi-Shu; Wang, Jingyu; Mahida, Prithviraj; Gao, Tuo; kzhang@umn.edu; Zhang, Kechun
These files contain data along with associated output from instrumentation supporting all results reported in Wang, J.; Niyompanich, S.; Tai, Y.-S.; Wang, J.; Bai, W.; Mahida, P.; Gao, T.; Zhang, K. Engineering of a highly efficient escherichia coli strain for mevalonate fermentation through chromosomal integration. Appl. Environ. Microbiol., 2016, 82, 7176–7184. Chromosomal integration of heterologous metabolic pathways is optimal for industrially relevant fermentation, as plasmid-based fermentation causes extra metabolic burden and genetic instabilities. In this work, chromosomal integration was adapted for the production of mevalonate, which can be readily converted into β-methyl-δ-valerolactone, a monomer for the production of mechanically tunable polyesters. The mevalonate pathway, driven by a constitutive promoter, was integrated into the chromosome of Escherichia coli to replace the native fermentation gene adhE or ldhA. The engineered strains (CMEV-1 and CMEV-2) did not require inducer or antibiotic and showed slightly higher maximal productivities (0.38 to ∼0.43 g/liter/h) and yields (67.8 to ∼71.4% of the maximum theoretical yield) than those of the plasmid-based fermentation. Since the glycolysis pathway is the first module for mevalonate synthesis, atpFH deletion was employed to improve the glycolytic rate and the production rate of mevalonate. Shake flask fermentation results showed that the deletion of atpFH in CMEV-1 resulted in a 2.1-fold increase in the maximum productivity. Furthermore, enhancement of the downstream pathway by integrating two copies of the mevalonate pathway genes into the chromosome further improved the mevalonate yield. Finally, our fed-batch fermentation showed that, with deletion of the atpFH and sucA genes and integration of two copies of the mevalonate pathway genes into the chromosome, the engineered strain CMEV-7 exhibited both high maximal productivity (∼1.01 g/liter/h) and high yield (86.1% of the maximum theoretical yield, 30 g/liter mevalonate from 61 g/liter glucose after 48 h in a shake flask).
Poly(isoprenecarboxylates) from Glucose via Anhydromevalonolactone
(2018-01-04) Ball-Jones, Nicolas; Hoye, Thomas R.; Fahnhorst, Grant W.; hoyex001@umn.edu; Hoye, Thomas R.
These are raw data files obtained during development of the following manuscript: Ball-Jones, N. R.; Fahnhorst, G. W.; Hoye, T.R. "Poly(isoprenecarboxylates) from Glucose via Anhydromevalonolactone" ACS Macro Lett. 2016, 1128–1131. The abstract of this document is the following, "A short and efficient synthesis of a series of isoprenecarboxylic acid esters and their corresponding polymers is presented. The base-catalyzed eliminative ring opening of anhydromevalonolactone (3) provides isoprenecarboxylic acid (6-H), which was further transformed to the isoprenecarboxylic acid esters. Reversible addition–fragmentation chain-transfer (RAFT) polymerization was used to synthesize high molecular weight (>100 kg mol–1) poly(isoprenecarboxylates) with dispersities (Đ) of ca. 1.5. The glass transition temperatures (Tg) and entanglement molecular weights (Me) of the poly(isoprenecarboxylates) were determined and showed similar trends to the Tg and Me values for analogous poly(acrylate esters). These new glucose-derived materials could provide a sustainable alternative to poly(acrylates).
Supporting data for Polymeric medical sutures: An exploration of polymers and green chemistry
(2018-01-17) Knutson, Cassandra M; Schneiderman, Deborah K; Yu, Ming; Javner, Cassidy H; Distefano, Mark D; Wissinger, Jane E; jwiss@umn.edu; Wissinger, Jane E
These files contain data along with associated output from instrumentation supporting all results reported in Knutson, C. M.; Schneiderman, D. K.; Yu, M.; Javner, C. H.; Distefano, M. D.; Wissinger, J. E. Polymeric medical sutures: An exploration of polymers and green chemistry. J. Chem. Educ. 2017, 94, 1761–1765. In Knutson, et. al. it was found that with new K–12 national science standards emerging, there is an increased need for experiments that integrate engineering into the context of society. Here we describe a chemistry experiment that combines science and engineering principles while introducing basic polymer and green chemistry concepts. Using medical sutures as a platform for investigating polymers, students explore the physical and mechanical properties of threads drawn from poly(ε-caprolactone) samples of different molecular masses and actual purchased absorbable and nonabsorbable medical sutures. An inquiry-based part of the experiment tasks students with designing their own experiment to probe the potential of melt blending poly(ε-caprolactone) with commercially available polylactide products in order to modify the properties of the “sutures” drawn. Through these lessons students gain an appreciation for the importance of plastics in our society and how scientists are working to develop more sustainable alternatives. Overall, this laboratory experiment provides a feasible, versatile, sophisticated laboratory experience that engages students in a relatable topic and meets many of the Next Generation Science Standards.
Supporting data for Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers
(2018-02-06) Haugan, Ingrid N; Maher, Michael J; Chang, Alice B; Lin, Tzu-Pin; Grubbs, Robert H; Hillmyer, Marc A; Bates, Frank S; bates001@umn.edu; Bates, Frank S
These files contain data along with associated output from instrumentation supporting all results reported in Haugan et. al. "Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers." In Haugan et. al. we found: The linear viscoelastic behavior of poly(norbornene)-graft-poly(±-lactide) was investigated as a function of grafting density and overall molar mass. Eight sets of polymers with grafting densities ranging from 0–100% were synthesized by living ring-opening metathesis copolymerization. Within each set, the graft chain molar mass and spacing between grafts were fixed while the total backbone length was varied. Dynamic master curves reveal that these polymers display Rouse and reptation dynamics with a sharp transition in the zero-shear viscosity data demonstrating that grafting density strongly impacts the entanglement molar mass. The entanglement modulus (Ge) scales with inverse grafting density (ng) as Ge ~ ng1.2 and Ge ~ ng0 in accordance with scaling theory in the high and low grafting density limits, respectively. However, a sharp transition between these limiting behaviors occurs, which does not conform to existing theoretical models for graft polymers. A molecular interpretation based on thin flexible chains at low grafting density and thick semiflexible chains at high grafting density anticipates the sharp transition between the limiting dynamical regimes.
Data for Process Design and Economic Analysis of Renewable Isoprene from Biomass via Mesaconic Acid
(2019-02-13) Dauenhauer, Paul J; Lundberg, Daniel J; Lundberg, David J; hauer@umn.edu; Dauenhauer, Paul J; Dauenhauer Research Laboratory - Chemical Engineering and Materials Science
The data contain the process design and economic information for the design and optimization of a chemical process to manufacture isoprene from biomass via mesaconic intermediate.
Entropically-driven macrolide polymerizations for the synthesis of aliphatic polyester copolymers using titanium isopropoxide
(2019-03-11) Amador, Adrian G; Watts, Annabelle; Neitzel, Angelika, E; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A; Hillmyer Research Group
Thermal and mechanical properties of sustainable aliphatic polyesters can be tuned through the synthesis of copolymers. The synthesis of two 14-membered macrolides are reported: a cyclic tetraester with alternating lactic acid (LA) and 3-hydroxypropionic acid (3HP) units and a cyclic diester with alternating glycolic acid (GA) and 2-methyl-1,3-propanediol (2MD) units. Ring-opening transesterification polymerization (ROTEP) of these macrolides to yield poly(LA-stat-3HP) and poly(GA-alt-2MD), respectively, were found to be modestly endothermic (ΔHp° = 2.0 kJ mol-1 and 0.5 kJ mol-1, respectively) and endoentropic (ΔSp° = 27 J mol-1 K-1 and 23 J mol-1 K-1, respectively). Inexpensive and non-toxic titanium isopropoxide Ti(Oi-Pr)4 functions as an active catalyst for these entropically-driven ROTEPs, achieving high conversions (> 90%) in under 1 h. The polymerizations exhibit control over molar mass with dispersity values < 1.7. P(GA-alt-2MD) is an amorphous polymer with a low glass transition temperature near −30 °C. P(LA-co-3HP) exhibits a glass transition temperature up to 13 °C and depending on the regioregularity, exhibits a melting temperature up to 96 °C.
Supporting data for "Physical Aging of Polylactide Based Graft Block Polymers"
(2019-11-08) Haugan, Ingrid; Lee, Bongjoon; Maher, Michael; Zografos, Aristotelis; Schibur, Haley; Jones, Seamus; Hillmyer, Marc; Bates, Frank; bates001@umn.edu; Bates, Frank; University of Minnesota Bates and Hillmyer research labs
These files contain primary data along with associated output from instrumentation supporting all results reported in Haugan et al. Physical Aging of Polylactide Based Graft Block Polymers. In Haugan et al. we found: Graft block polymers (BCPs) with poly(4-methylcaprolactone)-block-poly(lactide) (P4MCL-PLA) side chains containing 80 to 100% PLA content were synthesized with the aim of producing tough and sustainable plastics. These graft BCPs experience physical aging and become brittle over time. For short aging times, ta, the samples are ductile and shear yielding is the primary deformation mechanism. A double yield phenomenon emerges at intermediate ta where the materials deform by crazing followed by shear yielding. At long ta the samples become brittle and fail after crazing. PLA content strongly governs the time to brittle failure, where a 100% PLA graft polymer embrittles in 1 day, an 86% PLA graft BCP embrittles in 35 days, and at 80% PLA the material remains ductile after 210 days. Molecular architecture is also a factor in increasing the persistence of ductility with time; a linear triblock ages three times faster than a graft BCP with the same PLA content. SAXS and TEM analysis reveal the role of the rubbery P4MCL domains in initiating crazing by cavitation. Pre-straining the graft BCPs also significantly toughens these glassy materials. Physical aging induced embrittlement is eliminated in all the pre-strained polymers, which remain ductile after aging for 60 days. The pre-strained graft BCPs also demonstrate shape memory properties. When heated above Tg the stretched polymer within seconds returns to its original shape and recovers the original mechanical properties of the unstrained material. These results demonstrate that graft BCPs can be used to make tough, durable, and sustainable plastics and highlight the importance of understanding the mechanical performance of sustainable plastics over extended periods of time following processing.
Sustainable Polymer Framework
(2020-02) Wissinger, Jane E.; Ellison, Christopher J.; Dichtel, William R.; Chang, Alice B.; Trotta, Jacob T.; Yang, Anna B.; Bunyard, Clayton W.
The Sustainable Polymer Framework seeks to holistically define a sustainable polymer. The intended use is for members of the NSF Center for Sustainable Polymers to be able to identify and explain how their individual research project meets this definition. The goal is to introduce an integrated systems-thinking approach that considers the interconnection of all criteria and their net impact across the environment, economy, and society.
Supporting data for "Efficient Polymerization of Methyl-ε-Caprolactone Mixtures to Access Sustainable Aliphatic Polyesters"
(2020-02-26) Batiste, Derek, C; Meyersohn, Marianne S; Hillmyer, Marc A; Watts, Annabelle; hillmyer@umn.edu; Hillmyer, Marc A; University of Minnesota, Hillmyer Lab, Department of Chemistry
These files contain primary data along with associated output from instrumentation supporting all results reported in Batiste et. al. "Efficient Polymerization of Methyl-ε-Caprolactone Mixtures to Access Sustainable Aliphatic Polyesters." In Batiste et. al. we found: Aliphatic polyesters are a versatile class of materials that can be sourced from bioderived feedstocks. Poly(γ-methyl-ε-caprolactone) (PγMCL) in particular can be used to make degradable thermoplastic elastomers (TPEs) with outstanding mechanical properties. PγMCL can potentially be manufactured economically from p-cresol, a component of lignin bio oils. A complication is that additional manufacturing processes are necessary to isolate pure cresol isomers. Using mixed feedstocks of cresol isomers to access the corresponding methyl substituted ε-caprolactone (MCL) monomer mixtures would convey economic advantages to sourcing these materials sustainably. Moreover, the use of organocatalysts in lieu of traditional tin-based catalysts averts issues with potential environmental and human toxicity. With these motivations in mind, we explored the ring-opening transesterification polymerization (ROTEP) of MCL mixtures and characterized the molecular, thermal and rheological properties of the resulting copolymers. The molar mass of MCL mixtures that would be obtained from meta- and para-cresol can be readily modulated. The thermal and rheological properties of these statistical co- and terpolymers were at parity with pure PγMCL homopolymer. The use of diphenyl phosphate (DPP) and dimethyl phosphate (DMP) as organocatalysts enabled access to these materials on reasonable polymerization timescales and have potential to improve sustainability in the synthesis of these polyesters.
Supporting data for "4-Carboalkoxylated Polyvalerolactones from Malic Acid: Tough and Degradable Polyesters"
(2020-04-13) Hoye, Thomas; De Hoe, Guilhem; Fahnhorst, Grant; Hillmyer, Marc; hoye@umn.edu; Hoye, Thomas; Center for Sustainable Polymers
Eight 4-carboalkoxyvalerolactones (CRVLs), varying in the composition of their alkyl (R) side chains, were synthesized from malic acid and subjected to ring-opening transesterification polymerization (ROTEP) using diphenyl phosphate [DPP, (PhO)2PO2H] as a catalyst. Each CRVL produced a semicrystalline poly(4-carboalkoxyvalerolactone) (PCRVL), and the nature of the R group impacted the thermal transitions of these polyesters. Bulk polymerizations at 70 °C allowed for preparation of high molar mass samples that contained small amounts of branching, as evidenced by 1H NMR spectroscopy, MALDI spectrometry, size-exclusion chromatography, and eliminative degradation. Tensile testing of these lightly branched, high molar mass samples revealed that these polyesters are tough (tensile toughness values up to 88 ± 33 MJ•m–3) and have Young’s moduli (E) up to 186 ± 13 MPa. The acid- and base-catalyzed hydrolytic degradation of the PCRVLs was quantitatively monitored using total organic carbon analysis, and effect of the alkyl chain length on PCRVL hydrolysis rate was determined. Finally, the methyl ester variant of these malic acid-derived thermoplastics is known to be chemically recyclable.
Step-Growth Polyesters with Biobased (R)-1,3-Butanediol
(2020-08-26) DeRosa, Christopher A; Kua, Xiang Qi; Bates, Frank S; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A; University of Minnesota, Department of Chemistry
These files contain primary data along with associated output from "Step-Growth Polyesters with Biobased (R)-1,3-Butanediol" by Hillmyer et al. We present the synthesis and characterization of polymers containing 1,3-butanediol, also known as butylene glycol. Butylene glycol (BG) can be prepared from petroleum or sugar-based feedstocks. Petrol-based BG (petrol-BG) is isolated as a racemic mixture, whereas the bio-based BG from sugar that we utilized (Bio-BG), is enantiopure upon purification (>99.7%). In the presence of a titanium catalyst, polyesters were prepared by transesterification polymerization between petrol- or Bio-BG and various aliphatic and aromatic diacid derivatives. Polymers were analyzed by size-exclusion chromatography (SEC), 1H NMR and 13C NMR spectroscopies, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The synthesized polyesters were statistical in nature, according to 13C NMR spectroscopy, a result of the asymmetric nature of the BG-starting material. As a result, many of the polyesters were amorphous in nature with low thermal glass transitions (Tg) and no melting points (Tm). In many of the polyester derivatives, the racemic petrol-based and enantiopure bio-based BG polymers were nearly identical in thermal performance. Differences arose in semi-crystalline polyesters with long, aliphatic backbones (e.g., 1,14-tetradecanediocic acid; C14 diacid) or regioregular 4-hydroxybenzoate polyesters. This suggests the polymer microstructure (statistical versus sequenced) and the optical activity (racemic versus enantiopure) are important determinates in establishing the structure-property relationships in BG-containing polyesters. This work establishes synthetic protocols and the foundation for materials based on BG-containing polymers.
Supporting Information for Ligand effects on Decarbonylation of Palladium-acyl Complexes
(2020-10-22) Wiessner, Tedd C; Fosu, Samuel A; Parveen, Riffat; Vlaisavljevich, Bess; Tolman, William B; Rath, Nigam; wbtolman@wustl.edu; William, Tolman; University of South Dakota, Vlaisavljevich Lab; Washington University in Saint Louis, Tolman Lab, Department of Chemistry and Center for Sustainable Polymers
These files contain primary data along with associated output from instrumentation supporting all results reported in "Ligand effects on Decarbonylation of Palladium-acyl Complexes". In this work we found: The influences of perturbations of supporting phosphine ligands on the dehydrative decarbonylation of (Ln)Pd(II)(Cl)-hydrocinnamoyl com-plexes (L = PtBu3, n = 1; L = PPh3, n = 2; L = dppe, n = 1) to yield styrene were studied through combined experiment and theory. Abstraction of chloride from the complexes by silver and zinc salts, as well as sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, enhanced the efficiency of styrene formation, according to the trend in L: PtBu3 > dppe > PPh3. DFT calculations corroborated the experimental findings and provided insights into the ligand influences on reaction step barriers and transition state structures. Key findings include: a stable intermediate forms after chloride abstraction, from which -hydride elimination is rate-determining, the low coordination number for the PtBu3 case lowers reaction barriers for all steps, and the trans disposition of two ligands for L = PPh3 contributes to low efficiency for styrene production in that case.
Supporting data for Impact of macromonomer molar mass and feed composition on branch distributions in model graft copolymerizations
(2021-12-07) Zografos, Aristotelis; Lynd, Nathaniel A; Bates, Frank S; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A; University of Minnesota, Department of Chemistry
These files contain primary data along with associated output from instrumentation supporting all results reported in the referenced manuscript. Graft polymers are useful in a versatile range of material applications. Understanding how changes to the grafted architecture, such as the grafting density (z), the side-chain degree of polymerization (Nsc), and the backbone degree of polymerization (Nbb), affect polymer properties is critical for accurately tuning material performance. For graft-through copolymerizations, changes to Nsc and z are controlled by the macromonomer degree of polymerization (NMM) and initial fraction of the macromonomer in the feed (fMM0), respectively. We show that changes to these parameters can influence the copolymerization reactivity ratios and, in turn, impact the side-chain distribution along a graft polymer backbone. Poly((±)-lactide) macromonomers with NMM values as low as ca. 1 and as high as 72 were copolymerized with a small-molecule dimethyl ester norbornene comonomer over a range of fMM0 values (0.1 ≤ fMM0 ≤ 0.8) using ring opening metathesis polymerization (ROMP). Monomer conversion was determined using 1H nuclear magnetic resonance spectroscopy, and the data were fit using terminal and non-terminal copolymerization models. The results from this work provide essential information for manipulating Nsc and z, while maintaining synthetic control over the side-chain distribution for graft-through copolymerizations.
Supporting Data for Ductile Gas Barrier Poly(ester-amide)s Derived from Glycolide
(2022-06-21) Jang, Yoon-Jung; Sangroniz, Leire; Hillmyer, Marc; hillmyer@umn.edu; Hillmyer, Marc
The development of promising sustainable gas barrier materials, such as polyglycolide, poly(L-lactide), and poly(ethylene 2,5-furandicarboxylate) is an important alternative strategy to traditional plastics used for packaging where low gas permeability is beneficial. However, high degrees of crystallinity in these materials can lead to undesirably low material toughness. We report poly(ester-amide)s derived from glycolide and diamines exhibiting both high toughness and desirable gas barrier properties. These sustainable poly(ester-amide)s were synthesized from glycolide-derived diamidodiols and diacids. To understand structure-property relationships of poly(ester-amide)s, polymers with different numbers of methylene groups were compared with respect to thermal, mechanical, and gas barrier properties. As the number of methylene groups between ester groups increased, the melting temperature decreased and oxygen permeability increased in the even numbered methylene group series. We also found that they are readily degradable under neutral, acidic, and basic hydrolytic conditions. These high performance poly(ester-amide)s are promising sustainable alternatives to conventional gas barrier materials.
Supporting data for Dynamic Aliphatic Polyester Elastomers Crosslinked with Aliphatic Dianhydrides
(2023-01-27) Meyersohn, Marianne S; Haque, Farihah M; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc, A; University of Minnesota, Department of Chemistry
These files contain primary data along with associated output from instrumentation supporting all results reported in Meyersohn, M. et. al. "Dynamic Aliphatic Polyester Elastomers Crosslinked with Aliphatic Dianhydrides." In Meyersohn, M. et. al. we found: Chemically crosslinked elastomers are a class of polymeric materials with properties that render them useful as adhesives, sealants, and in other engineering applications. Poly(γ-methyl-ε-caprolactone) (PγMCL) is a hydrolytically degradable and compostable aliphatic polyester that can be biosourced and exhibits competitive mechanical properties to traditional elastomers when chemically crosslinked. A typical limitation of chemically crosslinked elastomers is that they cannot be reprocessed; however, incorporation of dynamic covalent bonds (DCBs) can allow for bonds to reversibly break and reform under an external stimulus, usually heat. In this work we the study dynamic behavior and mechanical properties of PγMCL elastomers synthesized from aliphatic dianhydride crosslinkers. The crosslinked elastomers in this work were synthesized using the commercially available crosslinkers, 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA), and 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and three-arm hydroxy-telechelic PγMCL star polymers. Stress relaxation experiments on the crosslinked networks showed an Arrhenius dependence of viscosity with temperature with an activation energy of 118 ± 8 kJ/mol, which agrees well with the activation energy of the exchange chemistry obtained from small molecule model studies. Dynamic mechanical thermal analysis and rheological experiments confirmed the dynamic nature of the networks and provided insight into the mechanism of exchange (i.e., associative, or dissociative). Tensile testing showed that these materials can exhibit high strains at break and low Young’s moduli, characteristic of soft, strong elastomers. By controlling the exchange chemistry and understanding the effect of macromolecular structure on mechanical properties, we prepared high performing elastomers that can be rapidly reprocessed at moderately elevated temperatures.
Supporting data for Star-to-bottlebrush transition in extensional and shear deformation of unentangled polymer melts
(2023-03-15) Zografos, Aristotelis; All, Helena A; Chang, Alice B; Hillmyer, Marc A; Bates, Frank S; bates001@umn.edu; Bates, Frank S; University of Minnesota Department Chemical Engineering and Material Science
These files contain primary data along with associated output from instrumentation supporting all results reported in Zografos et al. "Star-to-bottlebrush transition in extensional and shear deformation of unentangled polymer melts." A series of model poly((±)-lactide) (PLA) graft copolymers were synthesized using ring-opening metathesis polymerization and used to probe the star-to-bottlebrush transition in shear and extensional flows. Ten samples with backbone degrees of polymerization 10 < Nbb < 430, each containing one PLA side chain of length Nsc = 72 per two backbone repeat units, were investigated using small-amplitude oscillatory shear (SAOS) and extensional rheometry measurements. The star-like to bottlebrush transition was identified at Nbb = 50-70 using SAOS. In extension, melt strain hardening is absent in the star-like melts (Nbb < 50) but is prominent in the bottlebrush limit (Nbb > 70). The onset of melt strain hardening occurs at a timescale equivalent to the Rouse time of the backbone. A molecular interpretation of these results builds upon recent speculation related to strain-induced increases in interchain friction in bottlebrush polymers. These findings will be useful in designing bottlebrush melts to strain harden, which is critical in various types of processing methods involving extensional flows, including foaming, 3D printing, and film-blowing.
Supporting Data for High Performance Star Block Aliphatic Polyester Thermoplastic Elastomers using PDLA-b-PLLA Stereoblock Hard Domains
(2023-09-07) Liffland, Stephanie; Kumler, Margaret; Hillmyer, Marc A; hillmyer@umn.edu; Hillmyer, Marc A.; University of Minnesota Department of Chemistry
These files contain primary data along with associated output from instrumentation supporting all results reported in "High Performance Star Block Aliphatic Polyester Thermoplastic Elastomers using PDLA-b-PLLA Stereoblock Hard Domains" by Liffland et al. Star block (ABC)4 terpolymers consisting of a rubbery poly(γ-methyl-ε-caprolactone) (PγMCL) (C) core and hard poly(L-lactide) (PLLA) (B) and poly(D-lactide) (PDLA) (A) end-blocks with varying PDLA to PLLA block ratios were explored as high-performance, sustainable, aliphatic polyester thermoplastic elastomers (APTPEs). The stereocomplexation of the PDLA/PLLA blocks within the hard domains provided the APTPEs with enhanced thermal stability and an increased resistance to permanent deformation compared to non-stereocomplex analogs. Variations in the PDLA:PLLA block ratio yielded tunable mechanical properties likely due to differences in the extent and location of stereocomplex crystallite formation as a result of architectural constraints. This work highlights the improvements in mechanical performance due to stereocomplexation within the hard domains of these APTPEs and the tunable nature of the hard domains to significantly impact material properties, furthering the development of sustainable materials that are competitive with current industry standard materials.
Data for Thermodynamics and morphology of linear multiblock copolymers at homopolymer interfaces
(2023-11-09) Collanton, Ryan P; Ellison, Christopher J; Dorfman, Kevin D; dorfman@umn.edu; Dorfman, Kevin D
Block copolymers at homopolymer interfaces are poised to play a critical role in the compatibilization of mixed plastic waste, an area of growing importance as the rate of plastic accumulation rapidly increases. Using molecular dynamics simulations of Kremer–Grest polymer chains, we have investigated how the number of blocks and block degree of polymerization in a linear multiblock copolymer impacts the interface thermodynamics of strongly segregated homopolymer blends, which is key to effective compatibilization. The second virial coefficient reveals that interface thermodynamics are more sensitive to block degree of polymerization than to the number of blocks. Moreover, we identify a strong correlation between surface pressure (reduction of interfacial tension) and the spatial uniformity of block junctions on the interface, yielding a morphological framework for interpreting the role of compatibilizer architecture (number of blocks) and block degree of polymerization. These results imply that, especially at high interfacial loading, the choice of architecture of a linear multiblock copolymer compatibilizing surfactant does not greatly affect the modification of interfacial tension.