Copolycarbonates Based on a Bicyclic Diol Derived from Citric Acid

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Letter Cite This: ACS Macro Lett. 2019, 8, 454−459

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Copolycarbonates Based on a Bicyclic Diol Derived from Citric Acid and Flexible 1,4-Cyclohexanedimethanol: From Synthesis to Properties Yan Yu, Chengcai Pang,* Xueshuang Jiang, Zhiyi Yang, Jianbiao Ma, and Hui Gao* School of Material Science and Engineering, School of Chemistry and Chemical Engineering, Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, Tianjin University of Technology, Binshui West Road 391, Tianjin 300384, China Downloaded via CALIFORNIA STATE UNIV BAKERSFIELD on April 2, 2019 at 21:24:35 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

S Supporting Information *

ABSTRACT: Octahydro-2,5-pentalenediol (OPD), is a compelling citric acid−based bicyclic diol with excellent rigidity and thermal stability. Herein, a series of copolycarbonates (co-PCs) were synthesized, starting from OPD, 1,4-cyclohexanedimethanol (CHDM), and diphenyl carbonate (DPC). All polycarbonates are amorphous with glass transition temperatures increased when increasing the content in OPD units. Dynamic mechanical analysis (DMA) revealed the sub Tg β-relaxations at low temperatures originating from the CHDM conformational transition, indicative of the possibility of impact-resistance. Morphological analysis of the fracture surfaces revealed the toughening mechanism under tensile was shear yielding of the matrix triggered by internal cavitation. The incorporation of OPD steadily increased the Young’s modulus, from 482 to 757 MPa, with the OPD fraction increased from 0 to 30 mol %. As the OPD content further increased, a “ductile-to-brittle” transition occurred due to the low number-average molecular weight (Mn) and the low entangled strand density (high entanglement molecular weight).

N

decahydronaphthalate-2,6-dicarboxylate and CBDO are petroleum-derived. To increase stiffness, several biorenewable rigid structures have been explored.14−16 Isohexides, which are composed of isosorbide (ISB), isomannide, and isoidide, have been used to prepare homopolycarbonates with attractive high Tg.17−19 However, these sugar diols frequently underwent cross-linking reactions during the polymerization process due to the thermolabile tetrahydrofuran rings they contained.20−22 Another demerit of these sugar polycarbonates is their brittleness, as a result of their stiff backbones.20 The brittleness can be considerably addressed by copolymerization with flexible 1,4-cyclohexanedimethanol (CHDM).13 However, the sensitivity to heat remains an obstacle that greatly restrict them in general plastics’ applications. Thus, there is a great need to develop biobased diols with excellent rigidity and thermal stability. In advance of the present study, we reported a series of copolycarbonates (co-PCs) based on a bicyclic diol octahydro2,5-pentalenediol (OPD) derived from citric acid,23 from where we learned the excellent rigidity and thermostability of OPD. However, the main drawback of an OPD-based homopolycarbonate is its fragility. Inspired by the high Tg

owadays, biobased polymers are receiving considerable scientific attention owing to the diminishing reserves of crude oils.1−4 The modification of existing natural polymers, for example, cellulose,5 chitin,6 and starch,4 has been straightforward. In contrast, the synthetic polymers from biosourced chemicals is becoming more important owing to the rapid development of biorefineries in recent years.7 Bisphenol A (BPA) polycarbonate (BPA-PC) is a leading engineering thermoplastic in terms of outstanding transparency, high glass transition temperature (Tg), and impact resistance.8−10 Despite its widespread utilization, the exploration of biobased alternatives to BPA-PC is an area of intense scientific interest since BPA is nonrenewable and is regarded as endocrine disruptor.11 For instance, the Eastman Chemical Company developed a series of amorphous copolyesters with high Tg and superior impact properties from 2,2,4,4tetramethyl-1,3-cyclobutanediol (CBDO), 1,4-cyclohexanedimethanol (CHDM), and dimethyl terephthalate.12 It is wellestablished that CHDM is a flexible diol that can exert ductility to glassy polymers owing to its conformational transition (Figure S1), which increases the mobility of the polymer chains.13 Long’s group prepared a series of tough and ductile polyesters from dimethyl decahydronaphthalate-2,6-dicarboxylate with Tgs approaching 100 °C and ascribed their high impact strength to the high-energy absorption capability of the fused cyclohexylene rings that, in turn, correlates to their lowtemperature β-relaxations.10 Unfortunately, both dimethyl © XXXX American Chemical Society

Received: March 12, 2019 Accepted: March 25, 2019

454

DOI: 10.1021/acsmacrolett.9b00184 ACS Macro Lett. 2019, 8, 454−459

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ACS Macro Letters and impact strength of Tritan,12,24 we envisaged the synergy of OPD and CHDM to yield a series of high-Tg and impactresistant polycarbonates. In this paper, a series of co-PCs based on OPD and CHDM were successfully synthesized. By varying the feed ratios of monomers, the Tg and mechanical properties of the co-PCs can be finely adjusted to gain enhanced control over material design. Dynamic mechanical analysis (DMA) revealed sub-Tg β-relaxations at around −75 °C with minimal changes in intensity, suggesting the low temperature energy absorption exerted by CHDM. SEM images of the fractured surfaces revealed the toughening mechanism of CHDM was shear yielding of the matrix, triggered by internal cavitation, other than crazing. This study provides an interesting insight of the structure−property relationship in polymers that simultaneously containing the rigid and flexible units in the backbone. POxCyCs were synthesized via a two-step melt polycondensation (Scheme 1): prepolymerization at 130 °C under

content exceeds 50 mol %, which can be traced to its low reactivity. The chemical structures and compositions of co-PCs were investigated using 1H NMR and FT-IR (Figures 1 and S2).

Scheme 1. Melt Polymerization of POxCyC from OPD, CHDM, and DPCa

Figure 1. 1H NMR spectra of the obtained PCC, POC, and POxCyC copolycarbonates.

The peaks of the OPD moiety at δ 5.18, 5.00, 4.97, 2.71, 2.44, 2.27, and 1.68 ppm can be attributed to hydrogen atoms g, c, 3/7, a/e, 1/5, exocyclic (2/4/6/8/b/d/f/h), and endocyclic (2′/4′/6′/8′/b′/d′/f′/h′), respectively. Peak c overlapped peaks 3/7. The rest of the peaks located at δ 4.08, 3.96, 1.94, 1.86, 1.68, 1.58, 1.45, and 1.04 ppm were assigned to the hydrogen atoms 9 cis (c), 9 trans (t), 10 cis (c), 11a trans (t), 10 trans (t), 11a cis (c), 11b cis (c), and 11b trans (t) of CHDM moiety, respectively. The molar ratio of endoendo to the endoexo isomers in OPD units was determined by integrating the peaks g/c and 3/7 (Figure S3). The obtained results for all co-PCs approach the value of 4:1, indicating that the two isomers have similar reactivity, and epimerization did not occur during the polymerization process. Likewise, the estimated trans/cis ratios in the CHDM moiety for all series are 7:3 (Figure S4), implying that the CHDM configuration is also retained. In addition, integration of peak (g + c + 3 + 7) and peak (9 (t) + 9 (c)) led to the quantification of the molar fraction of OPD and CHDM in each series, as reported in Table S1, exemplifying that the targeted compositions can be achieved by adjusting the corresponding feeds. The microstructure of POxCyCs is an issue of prime importance, as it is directly related to thermal behaviors, transparency, and mechanical properties.31 In the extended 13C NMR spectrum (Figure S5), the carbonyl carbons with a chemical shift at around 155 ppm were used to clarify the dyad sequence distribution. Presumably, at least six multiple peaks would appear, corresponding to the CC, COendo, COexo, OendoOendo, OendoOexo, and OexoOexo dyads, where C and O represent the CHDM and OPD units, respectively. However, for PO50C50C and PO39C61C, only five peaks with adequate resolution could be observed, corresponding to the CC,

a

x and y represent the molar fraction of OPD and CHDM, respectively.

nitrogen (x and y represents the molar fraction of the OPD and CHDM units, respectively), followed by polycondensation at 200−230 °C under vacuum. In order to compensate for the low reactivity of OPD, a 10 mol % excess of OPD was used. 4Dimethylaminopyridine (0.1 wt % based on the diols) and lithium acetylacetonate (0.1 wt % based on the diols) were used as catalysts owing to their high catalytic activity.25 CHDM is generally regarded as nonrenewable, as its precursor, terephthalic acid (TPA), is industrially produced by the catalytic aerobic oxidation of p-xylene. However, several renewable routes emerged for the preparation of terephthalic acid from biorenewable feedstocks, including bioethylene,26,27 limonene,28 and dimethyl muconate obtained by crossmetathesis between methyl sorbate and methyl acrylate,29 thus, CHDM may potentially be sourced from renewable feedstocks. In addition, the carbonate source, DPC, can be regenerated from the phenol via phosgene-free methods, which is generated as a byproduct during the polycondensation process30 Therefore, all monomers used in this study are either biobased or can be reproduced via eco-friendly methods. All polycarbonates obtained were water white to slightly yellow, optically clear products, and no gelation occurred throughout the entire polymerization process, confirming the higher thermostability of OPD. Co-PCs involving OPD below 40 mol % displayed satisfied Mn confined in the 12100−20900 g mol−1 interval (Table S1), with polydispersity between 1.7 and 2.0. However, the Mn dramatically decreased once the OPD 455

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hand, the number of the β-H on OPD is four times the value of CHDM, which means that the β-H elimination rate on OC short sequences is much faster than that on the CC sequences. On the other hand, the endocyclic olefins formed arising from the OPD pyrolysis are thermodynamically stable compared to the exocyclic olefins derived from CHDM.34 Nevertheless, given that the difference between the Tg values (∼50 °C) and the onset of thermal degradation (∼270 °C) for most co-PCs are at least 220 °C, which enable various processing methods over a temperature window that is adequately wide. Figure S7 revealed the single-step glass transitions without any perceivable melting or crystallization peaks for all samples, confirming their amorphous features. For PCC, its amorphous characteristic is expected, as CHDM is a 7:3 mixture of transand cis-isomers, the trans-CHDM having both carbonate linkages in the opposite side of the cyclohexane ring, which tend to form linear, straight parallel structures, creates better conditions for crystallite formation. However, the cis-isomer, having both carbonate linkages on the same side of cyclohexane ring, is prone to introduce kinks in the polymer chains, hindering the formation of stable crystals.35 For POC, the bulky V-shaped bicyclic frame of OPD plays an important role in hindering the crystallization. Three possible packing manners, which are convex face to convex face, convex face to concave face, and concave face to concave face, may present in the POC chains, making this packing mode inefficiency and, hence, amorphous characteristic for POC.36 Furthermore, a previous study37 suggested that the different orientations of hydroxyl groups in the endoendo and endoexo isomers would dramatically reduce the crystallization ability. For co-PCs, amorphous characteristics are expected considering the amorphous structures of PCC and POC. With regard to the Tg values, PCC and POC have the lowest and the highest Tg values among all the polymers, which were 54.7 and 74.5 °C, respectively. Although we have been unsuccessful in elucidating the lower Tg value for POC compared to isosorbide homopolycarbonate (∼160 °C),25 two possible reasons for this are the following: (1) The two hydroxyl groups in isosorbide are located on the 2- and 5-positions. In contrast, the hydroxyl groups in OPD are located on the 3- and 7-positions. The intramolecular friction in isosorbide homopolycarbonate may be much higher than that in POC, resulting in the higher Tg for isosorbide polycarbonate. (2) The intrinsic rigidity of OPD is lower than isosorbide, despite the fact that both the framework of OPD and isosorbide are composed of two cis-fused fivemembered rings. Conformational transitions between the “envelope” and “half-chair” conformations on cyclopentane rings in OPD may occur unceasingly,38 resulting in the lower rigidity of OPD. Similar conformational transitions are absent or severely restricted in the case of isosorbide, due to the heterocyclic nature of tetrahydrofuran rings it contains. The molecular dynamics simulation on OPD using density functional theory (DFT) to theoretically assess its rigidity is now ongoing in our group. For POxCyCs, the incorporation of OPD into the backbone of PCC mildly improved the Tg, although not as remarkably as expected, which is possibly caused by the low OPD content and excellent flexibility of CHDM. The lower Tg observed for PO50C50C compared to PO39C61C can be correlated to its low molecular weight, despite the fact that its OPD content is higher than the latter, since the Tg is directly influenced by the polymer chain length. DMA probed the thermomechanical response of co-PCs (Figure 2 and Table S2). All the tested samples exhibited

COendo, COexo, OendoOendo, and OendoOexo diol-dyads, the OexoOexo dyad signal could not be observed owing to their rather low content. For PO29C71C, the signal arising from the OendoOexo disappeared, and only four peaks corresponding to the CC, COendo, COexo, and OendoOendo diol-dyads were observed. Similarly, the dyad signal number reduced to two in the case of PO17C83C and PO9C91C. In order to figure out the microstructures as precisely as possible, the 13C NMR spectra of PO50C50C and PO39C61C were chosen and the integration of the various dyad signals was performed. Based on these results, the dyad contents, the number-average sequence lengths, and the degree of randomness were determined using the following eqs 1−3, where NCC/OC, NCC/CC, and NOC/OC represent the molar fraction of dyads, calculated from the integral intensities of signals of carbonyl carbon from CO (or OC), CC, and OO dyads, respectively. nCC and nOC are the number-average sequence length of CHDM carbonate (CC) unit and OPD carbonate (OC) unit, respectively, the data provided are summarized in Table S1. Both R values are approximated to 1, implying the random structures for PO50C50C and PO39C61C. This conclusion can be reasonably extended to other co-PCs in this study. nCC =

nOC = R=

NCC/OC + 2NCC/CC NCC/OC

(1)

NCC/OC + 2NOC/OC NCC/OC

1 1 + nCC nOC

(2)

(3)

The thermal properties of these co-PCs were analyzed using TGA and DSC, the data provided are gathered in Table S2. The TGA curves as well as the corresponding derivative curves are shown in Figure S6. The thermal decomposition of POC and PCC occurred through one main step with the temperature for the maximum decomposition rate (Td) at 312 and 367 °C, respectively. The lower thermal stability observed for POC can be partially ascribed to its lower Mn compared to PCC (6500 vs 12200 g mol−1; the other causing factor will be discussed in the following part). In contrast, the pyrolysis for co-PCs took place through two well-differentiated stages which are closely related to the OPD contents, as shown in Figure S6b. To be specific, the replacement of CHDM by the OPD units caused an unevenly decreasing effect in both T5% and Td, which are confined at approximately 300 and 370 °C, respectively (Table S2). Furthermore, the intensity for the first peak increased in contrast to the second peak, for which it decreased with the increase of the OPD content. Therefore, it can be inferred that the first and second pyrolysis stages can be linked to the decomposition of the OC and CC short sequences, respectively, and the OC short sequences are less stable than the latter, which closely resembles the case of coPCs based on ISB and CHDM.13 Previous study correlated the thermolysis of the alicyclic diol-based polycondensates with the release of unsaturated compounds following a cis-β-elimination mechanism.32 Here, it is reasonable to assume that the thermolysis of co-PCs occurred following a cis-β-elimination mechanism similar to the case of an ISB-containing PC (Scheme S1).33 Considering the structural differences between OPD and CHDM, two possible factors are responsible for the lower thermal stability of the OC short sequence. On the one 456

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Figure 3. Fracture surfaces of co-PCs measured by SEM.

fracture for PCC, PO9C91C and PO17C83C, as evidenced by the appearance of fibril and randomly arrayed cavities in the fractured surfaces. For PO9C91C and PO17C83C, these cavities as well as the matrix around them become oriented to some extent, corresponding to the matrix shear yielding. The morphologies of these fractured surfaces revealed the tensile toughening mechanism of microvoids promoting shear yielding, other than crazing.43 In contrast, PO29C71C showed a typical brittle fracture, and the fracture surface was smooth with few stress-whitening zones and round microvoids, indicating a fracture transition from tough to brittle. The elucidation for mechanical properties of the co-PCs was conducted by tension experiments (Figure 4 and Table S3). All

Figure 2. Dynamic mechanical analysis of co-PCs (a) and lowtemperature dynamic mechanical analysis of co-PCs (b).

similar trends: storage modulus (E′) decreased with increasing temperature, implying their excellent flexibility exerted by CHDM. A precipitous drop in the modulus appeared as the temperature approached the Tg. Moreover, there is a concurrent sharp increase in the loss factor (tan δ), corresponding to the glass transition. DMA revealed that the order of Tg for the three is PCC < PO9C91C < PO17C83C, which corresponds well with the DSC results and is attributed to the increased chain rigidity upon incorporation of OPD. The E′ at 20 °C for each sample are in the order of PCC < PO9C91C < PO17C83C, which are 2563, 2844, and 3918 MPa, respectively (Table S2). The higher E′ observed for PO9C91C than PCC is expected considering the positive effect of OPD on E′ as well as the higher Mn of PO9C91C compared to PCC. The highest E′ for PO17C83C can be correlated with its highest Mn and OPD content among the three. The utilization of CHDM is to modify the toughness of POC due to its capability to provide toughness and fracture resistance, which correlates with the low-temperature βrelaxations in the glassy state.39 As highlighted in Figure 2b, PCC and PO9C91C showed sub Tg β-relaxations at around −75.0 °C, while the β-transition temperature shifted to −65 °C for PO17C83C with increasing the OPD content. A previous investigation identified the relaxation peak intensity as the indicator of impact-resistance performance.40 Overall, the relative intensities of β-relaxations in the three are much larger than in BPA-PC,41 suggesting the possibility for more highenergy absorption capacity. The impact-resistant performance of these co-PCs was further confirmed by the SEM images of the fractured surfaces (Figure 3). In general terms, the impact toughening effects could be correlated with the microscopic deformation extent of the fracture sites accompanied by stresswhitening, which is caused by the multicrazes and shear yielding of the matrix, indicative of the dramatic deformation of energy dissipation.42 Figure 3 shows the typical tough

Figure 4. Stress−strain curves of co-PCs at 25 °C and 3 mm s−1.

the tested samples exhibited plastic deformation with elastic deformation followed by yield and high elastic deformation. The incorporation of OPD units in the PCC chains consistently increased the Young’s modulus, from 482 MPa for PCC to 755 MPa for PO29C71C. This is an expected observation, as for general polymeric materials, the Young’s modulus is mainly affected by the rigidity and Mns.44 PO17C83C afforded the optimal comprehensive mechanical strength with Young’s modulus, ultimate tensile strength, and elongation at break of 668 MPa, 36 MPa, and 51%, respectively, which can be traced to the relatively high Mns and the appropriate OPD content. The OPD content of 30 mol % seems to be the border, as once it exceeded this value, 457

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Blends with Thermoplastic Starch. Macromol. Chem. Phys. 2008, 209, 991−1002. (5) Klemm, D.; Heublein, B.; Fink, H.-P.; Bohn, A. Cellulose: Fascinating Biopolymer and Sustainable Raw Material. Angew. Chem., Int. Ed. 2005, 44, 3358−3393. (6) Shamshina, J. L.; Zavgorodnya, O.; Berton, P.; Chhotaray, P. K.; Choudhary, H.; Rogers, R. D. Ionic Liquid Platform for Spinning Composite Chitin-Poly(lactic acid) Fibers. ACS Sustainable Chem. Eng. 2018, 6, 10241−10251. (7) Duan, R.-T.; He, Q.-X.; Dong, X.; Li, D.-F.; Wang, X.-L.; Wang, Y.-Z. Renewable Sugar-Based Diols with Different Rigid Structure: Comparable Investigation on Improving Poly(butylene succinate) Performance. ACS Sustainable Chem. Eng. 2016, 4, 350−362. (8) Gross, S. M.; Roberts, G. W.; Kiserow, D. J.; DeSimone, J. M. Synthesis of High Molecular Weight Polycarbonate by Solid-State Polymerization. Macromolecules 2001, 34, 3916−3920. (9) Freitag, D.; Fengler, G.; Morbitzer, L. Routes to New Aromatic Polycarbonates with Special Material Properties. Angew. Chem., Int. Ed. Engl. 1991, 30, 1598−1610. (10) Dennis, J. M.; Enokida, J. S.; Long, T. E. Synthesis and Characterization of Decahydronaphthalene-Containing Polyesters. Macromolecules 2015, 48, 8733−8737. (11) Auvergne, R.; Caillol, S.; David, G.; Boutevin, B.; Pascault, J.-P. Biobased Thermosetting Epoxy: Present and Future. Chem. Rev. 2014, 114, 1082−1115. (12) Booth, C. J.; Kindinger, M.; McKenzie, H. R.; Handcock, J.; Bray, A. V.; Beall, G. W. Copolyterephthalates containing tetramethylcyclobutane with impact and ballistic properties greater than bisphenol A polycarbonate. Polymer 2006, 47, 6398−6405. (13) Park, S.-A.; Choi, J.; Ju, S.; Jegal, J.; Lee, K. M.; Hwang, S. Y.; Oh, D. X.; Park, J. Copolycarbonates of bio-based rigid isosorbide and flexible 1,4-cyclohexanedimethanol: Merits over bisphenol-A based polycarbonates. Polymer 2017, 116, 153−159. (14) Lingier, S.; Spiesschaert, Y.; Dhanis, B.; De Wildeman, S.; Du Prez, F. E. Rigid Polyurethanes, Polyesters, and Polycarbonates from Renewable Ketal Monomers. Macromolecules 2017, 50, 5346−5352. (15) Llevot, A.; Grau, E.; Carlotti, S.; Grelier, S.; Cramail, H. From Lignin-derived Aromatic Compounds to Novel Biobased Polymers. Macromol. Rapid Commun. 2016, 37, 9−28. (16) Wilbon, P. A.; Chu, F.; Tang, C. Progress in Renewable Polymers from Natural Terpenes, Terpenoids, and Rosin. Macromol. Rapid Commun. 2013, 34, 8−37. (17) Wu, J.; Eduard, P.; Jasinska-Walc, L.; Rozanski, A.; Noordover, B. A. J.; van Es, D. S.; Koning, C. E. Fully Isohexide-Based Polyesters: Synthesis, Characterization, and Structure-Properties Relations. Macromolecules 2013, 46, 384−394. (18) Ma, S.; Webster, D. C.; Jabeen, F. Hard and Flexible, Degradable Thermosets from Renewable Bioresources with the Assistance of Water and Ethanol. Macromolecules 2016, 49, 3780− 3788. (19) Jasinska-Walc, L.; Villani, M.; Dudenko, D.; van Asselen, O.; Klop, E.; Rastogi, S.; Hansen, M. R.; Koning, C. E. Local Conformation and Cocrystallization Phenomena in Renewable Diaminoisoidide-Based Polyamides Studied by FT-IR, Solid State NMR, and WAXD. Macromolecules 2012, 45, 2796−2808. (20) Chatti, S.; Schwarz, G.; Kricheldorf, H. R. Cyclic and Noncyclic Polycarbonates of Isosorbide (1,4:3,6-Dianhydro-d-glucitol). Macromolecules 2006, 39, 9064−9070. (21) Wu, J.; Eduard, P.; Thiyagarajan, S.; Jasinska-Walc, L.; Rozanski, A.; Guerra, C. F.; Noordover, B. A. J.; van Haveren, J.; van Es, D. S.; Koning, C. E. Semicrystalline Polyesters Based on a Novel Renewable Building Block. Macromolecules 2012, 45, 5069− 5080. (22) Lavilla, C.; Alla, A.; Martínez de Ilarduya, A.; Benito, E.; GarcíaMartín, M. G.; Galbis, J. A.; Muñoz-Guerra, S. Carbohydrate-Based Polyesters Made from Bicyclic Acetalized Galactaric Acid. Biomacromolecules 2011, 12, 2642−2652.

both the ultimate strength and strain at break decreased, and a “ductile-to-brittle” transition occurred. This phenomenon can be correlated with their rather low Mns. Moreover, the brittleness is universal for rigid polymers, even at high molecular weights, as the stiff polymer chains preclude effective entanglement effects upon stretching. A series of co-PCs based on OPD and CHDM were synthesized. The expanded 13C NMR spectra and DSC revealed the stereoirregular structures and amorphous characteristics for all co-PCs. The co-PCs with OPD content ≤17 mol % exhibited sub Tg β-relaxations at low temperatures, originating from the conformational transition of CHDM units, suggesting improved toughness and impact-resistant capability. The SEM images revealed the tensile toughening mechanism of microvoids promoting shear yielding. Incorporation of OPD in the PCC chains consistently increased the Young’s modulus, and “ductile-to-brittle” transition occurred once the OPD content was ≥30 mol %. Future studies will focus on the exploration of more rigid and thermally stable alicyclic monomers from biobased feedstocks, which are promising alternatives to BPA for the production of high Tg yet robust polymers.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsmacrolett.9b00184. Materials, details of synthesis, polymer characterization and mechanical property tests (PDF)

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AUTHOR INFORMATION

Corresponding Authors

*Tel.: +86 22 60214251. E-mail: [email protected]. *E-mail: [email protected]. ORCID

Chengcai Pang: 0000-0003-0734-5290 Hui Gao: 0000-0002-5009-9999 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We are grateful to the National Natural Science Foundation of China (Nos. 21875164, 51503150, and 21674080), Tianjin Municipal Natural Science Foundation (Nos. 17JCQNJC03400 and 18JCZDJC37700), Training Project of Innovation Team of Colleges and Universities in Tianjin (TD13-5020), 131 talents program of Tianjin, and the leading talents program of Tianjin Educational Committee.

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REFERENCES

(1) Gandini, A.; Lacerda, T. M.; Carvalho, A. J. F.; Trovatti, E. Progress of Polymers from Renewable Resources: Furans, Vegetable Oils, and Polysaccharides. Chem. Rev. 2016, 116, 1637−1669. (2) Schneiderman, D. K.; Hillmyer, M. A. 50th Anniversary Perspective: There Is a Great Future in Sustainable Polymers. Macromolecules 2017, 50, 3733−3749. (3) Upton, B. M.; Kasko, A. M. Strategies for the Conversion of Lignin to High-Value Polymeric Materials: Review and Perspective. Chem. Rev. 2016, 116, 2275−2306. (4) Li, G.; Sarazin, P.; Favis, B. D. The Relationship between Starch Gelatinization and Morphology Control in Melt-Processed Polymer 458

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ACS Macro Letters

Glassy Poly(ester carbonate)s with Cyclohexylene Rings in the Backbone. Macromolecules 2003, 36, 9411−9420. (41) Liu, G.-C.; He, Y.-S.; Zeng, J.-B.; Xu, Y.; Wang, Y.-Z. In situ formed crosslinked polyurethane toughened polylactide. Polym. Chem. 2014, 5, 2530−2539. (42) Liu, G.-C.; He, Y.-S.; Zeng, J.-B.; Li, Q.-T.; Wang, Y.-Z. Fully Biobased and Supertough Polylactide-Based Thermoplastic Vulcanizates Fabricated by Peroxide-Induced Dynamic Vulcanization and Interfacial Compatibilization. Biomacromolecules 2014, 15, 4260− 4271. (43) Zhang, Z.; Kricheldorf, H. R.; Friedrich, C. Thermorheological and Mechanical Properties of Copolymers of Lactide, Isosorbide, and Different Phthalic Acids. Macromol. Rapid Commun. 2015, 36, 262− 268. (44) Lavilla, C.; Alla, A.; Martínez de Ilarduya, A.; Muñoz-Guerra, S. High Tg Bio-Based Aliphatic Polyesters from Bicyclic D-Mannitol. Biomacromolecules 2013, 14, 781−793.

(23) Liu, X.; Pang, C.; Ma, J.; Gao, H. Random Copolycarbonates Based on a Renewable Bicyclic Diol Derived from Citric Acid. Macromolecules 2017, 50, 7949−7958. (24) Mondschein, R. J.; Dennis, J. M.; Liu, H.; Ramakrishnan, R. K.; Nazarenko, S.; Turner, S. R.; Long, T. E. Synthesis and Characterization of Amorphous Bibenzoate (Co)polyesters: Permeability and Rheological Performance. Macromolecules 2017, 50, 7603−7610. (25) Li, Q.; Zhu, W.; Li, C.; Guan, G.; Zhang, D.; Xiao, Y.; Zheng, L. A non-phosgene process to homopolycarbonate and copolycarbonates of isosorbide using dimethyl carbonate: Synthesis, characterization, and properties. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 1387− 1397. (26) Bruijnincx, P. C. A.; Weckhuysen, B. M. Shale Gas Revolution: An Opportunity for the Production of Biobased Chemicals? Angew. Chem., Int. Ed. 2013, 52, 11980−11987. (27) Binder, J. B.; Raines, R. T. Simple Chemical Transformation of Lignocellulosic Biomass into Furans for Fuels and Chemicals. J. Am. Chem. Soc. 2009, 131, 1979−1985. (28) Colonna, M.; Berti, C.; Fiorini, M.; Binassi, E.; Mazzacurati, M.; Vannini, M.; Karanam, S. Synthesis and radiocarbon evidence of terephthalate polyesters completely prepared from renewable resources. Green Chem. 2011, 13, 2543−2548. (29) Saraçi, E.; Wang, L.; Theopold, K. H.; Lobo, R. F. Bioderived Muconates by Cross-Metathesis and Their Conversion into Terephthalates. ChemSusChem 2018, 11, 773−780. (30) Ishii, H.; Ueda, M.; Takeuchi, K.; Asai, M. Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by bis(benzonitrile)dichloropalladium in the presence of polyvinylpyrrolidone. Catal. Commun. 2001, 2, 17−22. (31) Zhang, M.; Moore, R. B.; Long, T. E. Melt transesterification and characterization of segmented block copolyesters containing 2,2,4,4-tetramethyl-1,3-cyclobutanediol. J. Polym. Sci., Part A: Polym. Chem. 2012, 50, 3710−3718. (32) Amari, T.; Nishimura, K.; Minou, K.; Kawabata, A.; Ozaki, Y. End-group characterization of homo- and copolyesters of cyclohexane-1,4-dimethanol. J. Polym. Sci., Part A: Polym. Chem. 2001, 39, 665−674. (33) Lee, J.; Lee, S.; Yoon, D.; Yoon, W. J.; Im, S. S.; Moon, B.; Oh, H. B. Tandem mass spectrometric analysis of isosorbide-1,4cyclohexane-dicarboxylic acid polyester oligomer cations using iontrap mass spectrometry. Rapid Commun. Mass Spectrom. 2013, 27, 1913−1918. (34) Turner, R. B.; Garner, R. H. Heats of Hydrogenation. V. Relative Stabilities in Certain Exocyclic-Endocyclic Olefin Pairs1. J. Am. Chem. Soc. 1958, 80, 1424−1430. (35) Yoon, W. J.; Hwang, S. Y.; Koo, J. M.; Lee, Y. J.; Lee, S. U.; Im, S. S. Synthesis and Characteristics of a Biobased High-Tg Terpolyester of Isosorbide, Ethylene Glycol, and 1,4-Cyclohexane Dimethanol: Effect of Ethylene Glycol as a Chain Linker on Polymerization. Macromolecules 2013, 46, 7219−7231. (36) Chan, I. Y. H.; Nguyen, V. T.; Bishop, R.; Craig, D. C.; Scudder, M. L. The Design of “Awkward” Molecules Expected to Yield Multiple Crystal Forms. Cryst. Growth Des. 2010, 10, 4582− 4589. (37) Fenouillot, F.; Rousseau, A.; Colomines, G.; Saint-Loup, R.; Pascault, J. P. Polymers from renewable 1,4:3,6-dianhydrohexitols (isosorbide, isomannide and isoidide): A review. Prog. Polym. Sci. 2010, 35, 578−622. (38) Chen, L. P.; Yee, A. F.; Moskala, E. J. The Molecular Basis for the Relationship between the Secondary Relaxation and Mechanical Properties of a Series of Polyester Copolymer Glasses. Macromolecules 1999, 32, 5944−5955. (39) Li, X.; Yee, A. F. Design of Mechanically Robust High-Tg Polymers: Mechanical Properties of Glassy Poly(ester carbonate)s with Cyclohexylene Rings in the Backbone. Macromolecules 2004, 37, 7231−7239. (40) Li, X.; Yee, A. F. Design of Mechanically Robust High-Tg Polymers: Synthesis and Dynamic Mechanical Relaxation Behavior of 459

DOI: 10.1021/acsmacrolett.9b00184 ACS Macro Lett. 2019, 8, 454−459