High Thermal Stability of Bio-Based ... - ACS Publications

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High Thermal Stability of Bio-Based Polycarbonates Containing Cyclic Ketal Moieties Gwang-Ho Choi, Da Young Hwang, and Dong Hack Suh* Department of Chemical Engineering, College of Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea S Supporting Information *

ABSTRACT: Bio-based polycarbonates containing cyclic ketal moieties were designed, and the bio-based diol monomer was synthesized by CQ with glycerol to improve their thermal properties and replace BPA in polymer industry. The molecular structure of the novel bio-based diol monomer 2,2:3,3-bis(4′-hydroxymethylethylenedioxy)-1,7,7-trimethylbicyclo[2.2.1]heptane (abbreviated as CaG) was analyzed by 1H, 13C, and 2D-COSY NMR techniques. GPC results show that CaG was reacted successfully and led to the high molecular weights for homopolycarbonate (Mw = 18 652) abbreviated as PCaGC and for copolycarbonate (Mw = 78 482) as PCaG20BPA80C. The high thermal stability (Td value above 350 °C) and glass transition temperature (Tg value from 128 to 151 °C) of PCaGCs and PCaGxBPAyCs were studied by TGA and DSC, respectively. Given the sufficient reactivity and high thermal stability, CaG is a promising renewable building block for applicable polymers.

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INTRODUCTION Bio-based polymers have drawn tremendous attention due to their potential as environmental-degradable, biocompatible, and nontoxic and by minimizing the petrochemicals in the past decades.1,2 Aliphatic polymers such as polyester,3,4 polyurethanes,5 polyamides,6 and polycarbonates7,8 constitute a renewable source for being used as polymer building blocks; there are abundant feedstock of bio-based polymers for industrial applications.9 Among the wide diversity of the carbohydrate-derived monomers, isosorbide (ISS) produced by dehydration of D-glucose coming from cereal starch has been regarded as a bio-based monomer for polycondensation due to its attractive rigidity, chirality, and nontoxicity. ISS is now an industrial product composed by two fused tetrahydrofuran rings, leading to the chemical and thermal stability.10 In the perspective of the polycarbonates for bisphenol A (BPA) replacement, polycarbonates synthesized via a condensation polymerization of ISS containing the two tetrahydrofuran rings with diphenylcarbonate. The success of polycarbonates based on BPA is the result of its processability combined with beneficial properties such as high mechanical strength, transparency, glass transition temperature (Tg), impact resistance, and dimensional stability.11,12 As the considering issues related to the health of humans, however, the fact that © XXXX American Chemical Society

BPA is a known the endocrine disruptor which has sparked significant interest in the development of replacement materials that are not based on BPA.13,14 Accordingly, ISS has been considered as bio-based diol monomer to replace BPA in polymer industry, until now.15 Despite the main alternative bio-based monomer, ISS has several problems in that low molecular weight caused by limited reactivity from the secondary hydroxyl group which led to disturb the polycondensation compared to that of primary hydroxyl group. These structural feature of ISS caused low molecular weight polymer; then the need for new bio-based monomer research has emerged recently. To overcome this structural feature, strategies including phenyl carbonate, hydroxymethylene, or chloroformate derivatives of ISS for synthesizing more reactive compound prior to polycondensation have been reported.16−19 But this methods still suffered from drawbacks such as high temperatures for polymerization, highly toxic reagents, or complicated processes.15 In this paper, this study deals with design and synthesis of a noble bio-based diol monomer 2,2:3,3-bis(4′-hydroxymethylReceived: May 26, 2015 Revised: August 17, 2015

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DOI: 10.1021/acs.macromol.5b01112 Macromolecules XXXX, XXX, XXX−XXX

Article

Macromolecules Scheme 1. Synthesis of Camphorquinone Diketal Glycerol (CaG) and Polymerization Reaction Leading to PCaGC Homopolycarbonates and PCaGxBPAyC Copolycarbonates

Glass transition temperatures (Tg) were measured by differential scanning calorimetry (DSC) using a DSC Q100 from TA Instruments. The measurements were carried out at a heating and cooling rate of 10 °C/min from 60 to 200 °C. Thermal data acquisition was carried out using Thermal Analysis software from TA Instruments. Gel permeation chromatography (GPC) in tetrahydrofuran (THF) was performed on a system equipped with a Waters 1515 Isocratic HPLC pump, a Waters 2414 refractive index detector, and a Waters 1717 plus autosampler. THF (1 g/L) was used as eluent at a flow rate of 1.0 mL/min. The molecular weights were calculated against polystyrene standards. Monomer Synthesis. 2,2:3,3-Bis(4′-hydroxymethylethylenedioxy)-1,7,7-trimethylbicyclo[2.2.1]heptane (camphorquinone diketal glycerol, abbreviated as CaG) was synthesized according to the reported procedure with reaction time and molar ratio of camphorquinone (CQ) to glycerol was modified.20 In a 250 mL flask, CQ (20 g, 120.32 mmol) was refluxed with glycerol (44 g, 0.48 mol) in 200 mL of benzene in the presence of p-toluenesulfonic acid monohydrate for 48 h with a Dean−Stark head. After the reaction, the organic layer was extracted with ethyl acetate. The combined organic layers were washed dilute sodium hydroxide (10%) and water. The resulting mixture was dried over magnesium sulfate, and the solvent was evaporated. The product was purified by column chromatography (ethyl acetate:chloroform = 2:1, R f = 0.3, silica gel) and recrystallization from hexane and obtained as white solid. Yield 70.3%; mp 95 °C. 1H NMR (299.9 MHz, CDCl3), δ (ppm): 4.42 (d, 2H, OH), 4.23−3.73 (m, 8H, OCH2CH), 3.55 (m, 2H, OCH), 1.91 (m, 1H, CCH2CH2), 1.81 (d, 1H, CCH), 1.67 (m, 1H, CHCH2CH2), 1.53 (m, 1H, CCH2CH2), 1.38 (m, 1H, CHCH2CH2), 1.16 (s, 3H, CCH3), 0.89 (s, 3H, CCH3), 0.84 (s, 3H, CCH3). 13C NMR (299.9 MHz, CDCl3): δ 114.79, 114.44, 77.85, 77.43, 65.69, 64.49, 61.41, 59.95, 52.57, 51.46, 45.01, 28.98, 21.34, 21.20, 21.02, 9.82. FT-IR: ν (cm−1) = 3430, 2954, 2894, 1476, 1392, 1315, 1209, 1119, 1035, 986. Melt Polymerization. General Procedure. PCaGC and PBPAC homopolycarbonates were obtained by reacting DPC with CaG or BPA, respectively. PCaGC was polymerized at different amount of CaG and DPC to optimize reaction conditions, and then PCaGxBPAyC copolycarbonates were obtained from a mixture of DPC, CaG, and BPA with the selected composition. The reactions were performed in a one-necked round-bottom flask equipped with a vacuum distillation outlet. The reactor was purged with N2 to remove

ethylenedioxy)-1,7,7-trimethylbicyclo[2.2.1]heptane (camphorquinone diketal glycerol, abbreviated as CaG) which has two reactive and flexible primary hydroxy groups derived from fully bio- and plant-based compounds to advance thermal stability and reactivity beyond ISS. In synthesis process, simple one-step synthesis of CaG is expected to induce a straightforward workup and separation leading to high purity as monomer of engineering bioplastics. It was anticipated that the rigid property derived from camphorquinone (CQ) was combined with high reactivity of primary alcohol derived from glycerol, generating two cyclic ketal moieties linked by norbornane.20 Additionally, cyclic ketal functional groups are more stable than the ester group against hydrolysis in acidic, neutral, and basic media, but this acid-cleavable linkages leave ketone and alcohol as degradation products; in our case those are the bio-based starting materials of a monomer.21,22 The plant-based CaG is expected to the next generation of cereal-based and other biomass compounds beyond ISS.

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EXPERIMENTAL SECTION

Materials. DL-Camphorquinone (CQ, 98%), glycerol (≥99.5%), ptoluenesulfonic acid (p-TSA, monohydrate, 98.5%), benzene (anhydrous, 99.8%), sodium bicarbonate (NaHCO3, 99.0%), diphenyl carbonate (DPC, 99%), bisphenol A (BPA, >99.0%), and chloroformd (99.8 atom % D) were purchased from Sigma-Aldrich. CQ and DPC were recrystallized from ethanol, BPA was recrystallized from acetic acid:water = 1:1, p-TSA was recrystallized from ethanol/water, and others were used as received. Characterization. 1H and 13C NMR spectra were recorded on a Mercury Plus spectrometer operating at 299.9 MHz at room temperature. Correlation spectra (COSY) were obtained from Jeol JNM-LA400 at 400 MHz at room temperature. Fourier transform infrared (FT-IR) spectra were obtained on a 460 plus spectrometer from JASCO. The measurement resolution was set at 4 cm−1, and the spectra were collected in the range 4000−500 cm−1. The thermal stability of the polymers was determined by thermogravimetric analysis (TGA) with a SDT Q6000 apparatus from TA Instruments. The samples were heated from 50 to 600 °C at a heating rate of 10 °C/min under a nitrogen flow of 100 mL/min. B


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Macromolecules

Figure 1. (a) 1H and (b) 13C NMR spectra of CaG. reduced to 160 mbar and held for 1 h and reduced to 1 mbar and held for 10 min. The reaction mixture was further heated to 260 °C for 10 min and to 280 °C for 30 min. Finally, the reaction mixture was cooled to room temperature, and the pressure was returned to atmospheric pressure using N2 to prevent oxidative degradation. The formed polymer was dissolved in chloroform, the solution was filtered, and the

any residual air and avoid oxidation during the polymerization. An excess of DPC to diol mixture was used, and sodium bicarbonate (NaHCO3, 0.6% molar with respect to diol monomers) was the catalyst of choice. The reaction mixture was heated in a heating mantle to 200 °C and held at this temperature for 1 h. The vacuum was reduced to 200 mbar and held for 15 min. The temperature was then increased slowly to 240 °C and held for 10 min. The vacuum was C


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Macromolecules

Table 1. Molar Composition, Yield, Molecular Weight, and Thermal Properties of PCGxBPAyC Homo- and Copolycarbonates molar composition feed

copolycarbonate

molecular weight

copolycarbonate

CaG

BPA

CaG

BPA

yield (%)

Mna

PCaGC PCaG80BPA20C PCaG60BPA40C PCaG40BPA60C PCaG20BPA80C PBPAC

100.0 80.0 60.0 40.0 20.0 0.0

0.0 20.0 40.0 60.0 80.0 100.0

100.0 86.0 58.5 36.7 12.3 0.0

0.0 14.0 41.5 63.3 87.7 100.0

46.0 40.1 39.6 36.2 16.1 52.5

8283 8672 12743 12157 17963 6917

thermal properties (°C)

Mwa

a

D

T5%b

Tdc

Tgd

18652 17034 26781 59271 78482 22947

2.25 1.96 2.10 4.87 4.37 3.32

298.0 275.8 292.6 311.4 329.7 333.7

357.7 308.3 369.8 371.2 390.6 369.1

128.3 130.2 134.6 140.9 151.2 120.6

Number-average and weight-average molecular weights in g mol−1 and dispersities measured by GPC in THF against PS standards. bTemperature at which 5% weights loss was observed. cTemperature for the maximum degradation rate. dGlass-transition temperature taken as the inflection point of the heating DSC traces. a

polymer precipitated by dropwise addition to methanol. The polymer was filtered and dried in a vacuum oven at 60 °C for 24 h. NMR Characterization of PCaGC Homopolycarbonate. 1H NMR (299.9 MHz, CDCl3), δ (ppm): 4.60−3.40 (m, 10H, OCH2CH, OCH, CH2OH), 1.89 (broad s, 1H, CCH2CH2), 1.71 (broad s, 1H, CCH),1.68 (broad s, 1H, CHCH2CH2), 1.52 (broad s, 1H, CCH2CH2), 1.35 (m, 1H, CHCH2CH2), 1.14 (broad s, 3H, CCH3), 0.85 (broad s, 3H, CCH3), 0.80 (broad s, 3H, CCH3). NMR Characterization of PBPAC Homopolycarbonate. 1H NMR (299.9 MHz, CDCl3), δ (ppm): 7.24 (d, 4H, Ar−H), 7.18 (d, 4H, Ar− H), 1.68 (broad s, 6H, CCH3). PCaGxBPAyC Copolycarbonates. 10% molar excess of DPC to the diol mixture. 1H NMR (299.9 MHz, CDCl3), δ (ppm): 7.24 (d, y·4H, Ar−H), 7.18 (d, y·4H, Ar−H), 4.60−3.40 (m, x·10H, OCH2CH, OCH, CH2OH), 1.89 (broad s, x·1H, CCH2CH2), 1.71 (broad s, x· 1H, CCH),1.68 (broad s, x·1H, CHCH2CH2), 1.65 (broad s, y·6H, CCH 3 ), 1.52 (broad s, x·1H, CCH 2 CH 2 ), 1.35 (m, x·1H, CHCH2CH2), 1.14 (broad s, x·3H, CCH3), 0.85 (broad s, x·3H, CCH3), 0.80 (broad s, x·3H, CCH3).

carbons as 114.79 and 114.44 ppm, respectively. Studied with 2D COSY NMR, the cyclic ketal protons at k and k′ have dihedral coupling with the protons at l, m and l′, m′, respectively. This result confirms the presence of the two cyclic ketal rings on the rigid CQ moiety, which features could supply CaG monomer to the stiffness effect on the polymer chain.24 Because of the rigid CQ structure, protons f, f′ and g, g′ have different shifts and proton h coupled with only one hydrogen, resulting in multiplet at 1.91, 1.67, 1.53, and 1.38 and doublet of h at 1.81 ppm. As the mono ketal or nonreacted compounds have different shift of h proton by the deshielding effect of the carbonyl group, this suggests that the complex peak originates from the mixture of diastereoisomeric compounds.25 The 1H NMR spectra of CaG can be found in the Supporting Information. The polymerizations of the fully bio-based CaG homopolycarbonates, abbreviated as PCaGC, were carried out by the melt process of CaG with DPC and NaHCO3 as catalyst yielding polymers successively. The molar composition ratio in feed of melt process polymerization, yield, molecular weights, and thermal properties derived from the shown thermograms (Figure S3); viz. onset decomposition temperatures (T5%) and temperatures for maximum degradation rate (Td), are listed in Table S1. More importantly, for the properties to adequate for variety application, bio-based diol monomer CaG was copolymerized with BPA to tune the thermal properties. Table 1 gives an overview of the molar composition, yield, Mn, Mw, D, T5%, and Td of the PCGxBPAyC copolycarbonates. First, the purified PCaG homopolycarbonates were isolated in 46.0% yield, with the Mw value of 18 652 g/mol and a polydispersity (D) of 2.25. This confirms that two primary hydroxy groups react effectively with DPC and are polymerized to high molecular weights in broad mol % of CaG to DPC. Becaues the PCaG homopolycarbonates show T5% at 298 °C, the melt process was conducted below this temperature but far above the melting temperature of CaG monomer (92 °C) and glass-transition temperature (128.3 °C). In the commercial production of conventional BPA polycarbonates, equimolar amounts of BPA and DPC are reacted while evacuating the byproduct phenol.1 DPC was reacted with CaG from equimolar to 0.4 mol excess ratio to compensate the evacuated weights. Sodium bicarbonate (NaHCO3) was selected as the base catalyst of melt polymerization. LiOH and LiAcac used as catalyst or 0.06% mol of NaHCO3 to diol resulted in unsuccessful polymerization; meanwhile, homopolycarbonates were gained when 0.6 mol % of NaHCO3 to diol was used.

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RESULTS AND DISCUSSION The new bio-based camphorquinone diketal glycerol (CaG) monomer was prepared from DL-camphorquinone (CQ) following the chemical synthetic route depicted in Scheme 1. The ketone groups on CQ yielded primary alcohol groups through the one step ketalization reaction, which were designed to improve the reactivity leading to a high molecular weights polymer. Since the two cyclic ketal rings are linked to rigid norbornane moiety, a fairly high degree of rigidity should be expected for CaG. The rigidity of the monomer induces the stiffness leading to high glass transition temperature rather than independently linked by single C−C bond,23 which is critical for the preparation of polymers.24 Moreover, recent bio-based monomers for improvement of the mechanical and/or the thermal properties of polycarbonates have several steps for preparation, but CaG, as it is synthesized in one step, needs no protection and deprotection steps, and the organic acid catalyst was simply removed by work-up process. The polymerizations involving CaG were carried out in the melt polycondensation conditions applied in the industrial process. The molecular structure of novel bio-based diol monomer CaG was analyzed 1H NMR, 13C NMR, and 2D COSY spectroscopy (Figure 1). In general, all proton and carbon signals of the monomers can be found at the expected chemical shift values with matching multiplicities. The asymmetry of CQ and each cyclic ketal groups result in complex 1H NMR spectra at 4.23−3.73 ppm of l, l′, m, m′ hydrogens as multiplet and 65.69, 64.49, 61.41, 59.95 ppm in 13C NMR. Likewise, the asymmetric structure of CaG results in different shift of j and i D


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Macromolecules

Figure 2. Compared 1H NMR spectra of PCaGxBPAyCs.

The thermal properties of the homopolycarbonates have been systematically studied by TGA and differential scanning calorimetry (DSC). All homopolycarbonates show one major decomposition step in the temperature range 230−420 °C (Figure S3). During this step, over 85 wt % of the initial mass of the polymer is lost, resulting in almost no weight change and 1−12 wt % residual weights at 500 °C. Linear poly(alkylene dicarboxylates) are known to decompose almost completely under the same TGA conditions.4,26 Similar thermal decomposition phenomena have been reported for other polymer systems containing cyclic ethers.26 Hence, the residual weights observed for PCaGCs are the degradation products of the CaG moieties. As the molar composition of DPC in the polymer-

ization feed ratio was increased, temperatures at maximum degradation rate (Td) decreased. But T5% is similar to 300 °C and Td is higher than this temperature, indicating thermal stability of PCaGCs can be used to injection molding which operates at temperature above 300 °C.27 The DSC curves of entries 1−5 are shown (Figure S4). The most high Tg was observed by entry 2 (128.3 °C) which has the highest molecular weights. Entries 1 and 3 show comparable molecular weights with entry 2 while Tg values were above 125 °C. In these experiments, DPC molar excess ratio was chosen as 1.1 because it is thought that optimized condition for highest molecular weights, sufficient high thermal degradation temperature (T5% and Td), and highest Tg in the studied condition. It E


Article

Macromolecules should be noted that the rigid structure of CaG drives higher Tg above 50 °C than 4,8-bis(hydroxymethyl)tricyclodecane homopolycarbonate while at relatively low molecular weights.28 Second, the BPA homopolymer (PBPAC) was polymerized at the same condition to be compared with PCaGxBPAyC copolycarbonates. The precipitated PCaGxBPAyC copolycarbonates were obtained with weight-average molecular weights confined in the 17 034−78 482 g mol−1 interval and dispersities in the 1.96−4.37 range. The GPC analysis of the obtained product afforded that all copolycarbonates had compositions very close to those of their corresponding feeds. In particular, the feed ratio of CaG monomer was selected from 20 to 80 mol %. The yield of the PCaGxBPAyC copolycarbonates was decreased as the BPA feed composition was increased except the PBPAC. The molecular weight of PCaG86BPA14C was similar to PCaGC, and higher molecular weights were obtained. The increasing trend of the Mn and the Mw was observed as the BPA feed ratio was raised. Even though the Mw was elevated, Mn was not increased as Mw, leading to a high D value. The most high D (4.87) and Mw (78 472) were observed in PCaG20BPA80C copolycarbonates. This result suggests that the CaG monomer was reacted with the DPC faster than or similar to the BPA in this polymerization condition even though the BPA has two aromatic hydroxyl groups. The resulted molar ratios of copolycarbonates were calculated by the aromatic hydrogen on BPA with the methyl hydrogen on CQ in 1H NMR spectra (Figure 2). Data provided by this analysis are given in Table 1, where it can be seen that the bicyclic monomers CaG and BPA were successfully polymerized. In general, all proton and carbon signals from the repeating units of the polymers can be found at the expected chemical shift values with matching multiplicities. The peaks of the CaG moiety at 4.60−3.40, 1.89, 1.67, 1.35, 1.14, and 0.84 ppm were assigned to hydrogen atoms l, l′, m, m′, k, k′; f; f′, g, h; g′; d; a, b, respectively, while the BPA moiety at 7.24, 7.18, and 1.68 ppm was assigned to hydrogen atoms p, o, and q, respectively. The final compositions of the copolycarbonates are comparable to the CaG:BPA feed compositions. The higher reacted composition than the feed ratio was shown at PCaG80BPA20C copolycarbonates, and others were shown the analogous amount of feed ratio. TGA curves of PCaGxBPAyCs are given in Figure 3 taking PBPAC homopolymer as reference. The T5% and Td of the copolymers are listed in Table 1. The same as thermogram of PCaGCs, PCaGxBPAyCs decompose in one step. The PCaGxBPAyCs are thermally stable up to 280 °C. Thermal decomposition of the PCaGxBPAyCs started to be detectable at about 270 °C with onset temperatures (measured for 5% of weights loss) being close to 330 °C. This behavior indicates two monomers were copolymerized randomly and/or CaG and BPA decomposed at the similar rate. Exceptionally, PBPAC decompose in more than one step but previously studied PBPAC which was degraded in one step. It has been reported that when polycarbonates are thermally degraded in the temperature range 300−400 °C and a continuously evacuated system, PC rapidly cross-links to form an insoluble gel.29 The observed insoluble mixture after polymerization reaction of PBPAC suggests that this gel was induced the multistep degradation and BPA was degraded at lower temperature than CaG in polymerization condition. The values of T5% and Td for these samples increase with the content of BPA as BPA is more thermally stable than CAG. The remaining weights present a tendency to increase with the content of the BPA, as BPA is

Figure 3. TGA traces of PCaGxBPAyCs recorded from 50 to 600 °C at 10/min under a N2 atmosphere.

more stable than CaG. In general, a Td value of 370−390 °C is sufficiently high to enable the general application of PCaGxBPAyCs in the plastics industry.15 And it is comparable to T5% values of IS-BPA copolycarbonates (310−334 °C) and Td values of IS homopolycarbonates (379−385 °C).30,31 The Tg values of copolycarbonates were studied by DSC (Figure 4 and Table 1). The DSC analysis revealed that the

Figure 4. DSC curves of PCaGxBPAyCs. The experiments were carried out from 60 to 200 °C at a heating rate of 10 °C/min.

higher Tg value induced by the increased CaG contents. As shown in Figure 4, one unique Tg value was detected for all the samples and the Tg values decreased from 151.2 to 130 °C with the increasing content of CaG. PCaG20BPA80C shows the highest Tg value of 151.2 °C which is higher than a commercial BPA PC (150 °C) while PBPAC in our experiment shows similar Tg value to the PCaGCs.32 Therefore, we suggest the same reason that cyclic ketal linked by rigid norbornane ring induce stiffness leading to high glass transition temperature rather than independently linked by single C−C bond.23 F


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(6) Caouthar, A.; Roger, P.; Tessier, M.; Chatti, S.; Blais, J. C.; Bortolussi, M. Eur. Polym. J. 2007, 43 (1), 220−230. (7) García-Martín, M. G.; Pérez, R. R.; Hernández, E. B.; Espartero, J. L.; Muñoz-Guerra, S.; Galbis, J. A. Macromolecules 2005, 38 (21), 8664−8670. (8) Chatti, S.; Schwarz, G.; Kricheldorf, H. R. Macromolecules 2006, 39 (26), 9064−9070. (9) Munoz-Guerra, S.; Lavilla, C.; Japu, C.; Martinez de Ilarduya, A. Green Chem. 2014, 16 (4), 1716−1739. (10) Fenouillot, F.; Rousseau, A.; Colomines, G.; Saint-Loup, R.; Pascault, J. P. Prog. Polym. Sci. 2010, 35 (5), 578−622. (11) Gross, S. M.; Roberts, G. W.; Kiserow, D. J.; DeSimone, J. M. Macromolecules 2001, 34 (12), 3916−3920. (12) Wimberger-Friedl, R. Prog. Polym. Sci. 1995, 20 (3), 369−401. (13) Von Goetz, N.; Wormuth, M.; Scheringer, M.; Hungerbühler, K. Risk Anal. 2010, 30 (3), 473−487. (14) Burke, D. J.; Kawauchi, T.; Kade, M. J.; Leibfarth, F. A.; McDearmon, B.; Wolffs, M.; Kierstead, P. H.; Moon, B.; Hawker, C. J. ACS Macro Lett. 2012, 1 (11), 1228−1232. (15) Feng, L.; Zhu, W.; Li, C.; Guan, G.; Zhang, D.; Xiao, Y.; Zheng, L. Polym. Chem. 2015, 6 (4), 633−642. (16) Yokoe, M.; Aoi, K.; Okada, M. J. Polym. Sci., Part A: Polym. Chem. 2003, 41 (15), 2312−2321. (17) Wu, J.; Eduard, P.; Jasinska-Walc, L.; Rozanski, A.; Noordover, B. A. J.; van Es, D. S.; Koning, C. E. Macromolecules 2013, 46 (2), 384−394. (18) Kricheldorf, H. R.; Sun, S.-J.; Gerken, A.; Chang, T.-C. Macromolecules 1996, 29 (25), 8077−8082. (19) Sun, S.-J.; Schwarz, G.; Kricheldorf, H. R.; Chang, T.-C. J. Polym. Sci., Part A: Polym. Chem. 1999, 37 (8), 1125−1133. (20) Liu, J.-H.; Wang, H.-Y. J. Appl. Polym. Sci. 2003, 90 (11), 2969− 2978. (21) Lavilla, C.; Alla, A.; Martínez de Ilarduya, A.; Benito, E.; GarcíaMartín, M. G.; Galbis, J. A.; Muñoz-Guerra, S. J. Polym. Sci., Part A: Polym. Chem. 2012, 50 (16), 3393−3406. (22) Binauld, S.; Stenzel, M. H. Chem. Commun. 2013, 49 (21), 2082−2102. (23) Lavilla, C.; Alla, A.; Martínez de Ilarduya, A.; Muñoz-Guerra, S. Biomacromolecules 2013, 14 (3), 781−793. (24) Lavilla, C.; de Ilarduya, A. M.; Alla, A.; García-Martín, M. G.; Galbis, J. A.; Muñoz-Guerra, S. Macromolecules 2012, 45 (20), 8257− 8266. (25) Ellis, M. K.; Golding, B. T.; Maude, A. B.; Watson, W. P. J. Chem. Soc., Perkin Trans. 1 1991, No. 4, 747−755. (26) Lavilla, C.; Alla, A.; Martínez de Ilarduya, A.; Benito, E.; GarcíaMartín, M. G.; Galbis, J. A.; Muñoz-Guerra, S. Biomacromolecules 2011, 12 (7), 2642−2652. (27) Puglisi, C.; Sturiale, L.; Montaudo, G. Macromolecules 1999, 32 (7), 2194−2203. (28) Park, J. H.; Jeon, J. Y.; Lee, J. J.; Jang, Y.; Varghese, J. K.; Lee, B. Y. Macromolecules 2013, 46 (9), 3301−3308. (29) Davis, B. K. Nature 1965, 206 (4982), 397−398. (30) Lee, C.-H.; Takagi, H.; Okamoto, H.; Kato, M. J. Appl. Polym. Sci. 2013, 127 (1), 530−534. (31) Li, Q.; Zhu, W.; Li, C.; Guan, G.; Zhang, D.; Xiao, Y.; Zheng, L. J. Polym. Sci., Part A: Polym. Chem. 2013, 51 (6), 1387−1397. (32) Noordover, B. A. J.; Haveman, D.; Duchateau, R.; van Benthem, R. A. T. M.; Koning, C. E. J. Appl. Polym. Sci. 2011, 121 (3), 1450− 1463.

CONCLUSION For the first time, bio-based diol monomer was successfully prepared by cyclic ketalized reaction of rigid camphorquinone with glycerol. In contrast to other bio-based diols used for polycondensates such as isosorbide, these diols could be synthesized in one-pot reaction without complex preparation steps from environmentally friendly reagents. By taking special concern of the reaction conditions, homopolycarbonates were synthesized successfully through melt polymerization with relatively high Mw value of of 18 652 and Td value of 357.7 °C. And the copolycarbonates were polymerized which have molar compositions similar to the corresponding feeds and relatively high Mw value of 78 482. As it is known to polycarbonates, a high molar ratio of BPA afforded PCaGxBPAyCs showing high thermal stability Td of 390.6 °C for PCaG20BPA80C. The plant-based diol investigated in this work as monomer for polycondensation stands out not only for being a sustainable compound but also for providing polycarbonates with satisfactory molecular weights.

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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/acs.macromol.5b01112. 1 H NMR and FT-IR spectra of CaG monomer, TGA traces, and DSC curves of PCaGCs (PDF)

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AUTHOR INFORMATION

Corresponding Author

*E-mail [email protected]; Fax (+81) 2220 4523; Tel (+81) 2220 0523 (D.H.S.). Author Contributions

D. H. Suh made substantial contributions to conception and design. G. H. Choi performed the experiments, analyzed the data, and wrote the paper. D. Y. Hwang contributed to revise the article. D. H. Suh and G. H. Choi discussed the results and implications. D. H. Suh commented on the manuscript at all stages. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This research was supported by the Industrial Strategic Technology Development Program granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (10045051).

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REFERENCES

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