The Role of Melt Memory and Template Effect in Complete. Stereocomplex Crystallization and Phase Morphology of Polylactides

Transcription

1 Supporting Information The Role of Melt Memory and Template Effect in Complete Stereocomplex Crystallization and Phase Morphology of Polylactides Yan-Fei Huang, Zheng-Chi Zhang, Yue Li, Jia-Zhuang Xu, Ling Xu, Zheng Yan, Gan-Ji Zhong * and Zhong-Ming Li College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu , People s Republic of China * Corresponding author. Tel.: ; Fax: ganji.zhong@scu.edu.cn (G.J. Z.). 1

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3 Figure S1. 1D-WAXD profiles of the samples (a) at different temperatures during the heating process, (b) at different durations during the isothermal process, and (c) at different temperatures during the cooling process of thermal treatment at 190 C. 3

4 Figure S2. (a) 1D-WAXD profiles of the samples (a) at different temperatures during the heating process, (b) at different durations during the isothermal process, and (c) at different temperatures during the cooling process of thermal treatment at 210 C. 4

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6 Figure S3. (a) 1D-WAXD profiles of the samples (a) at different temperatures during the heating process, (b) at different durations during the isothermal process, and (c) at different temperatures during the cooling process of thermal treatment at 230 C. DSC experiments were carried out by utilizing DSC Q2000 (TA Instruments, U.S.A.). The endothermic and exothermic information on samples cut from the center (1 2 mm away from sample surface, and mm away from sample ends) of injection-molded bars was collected during following procedure: (i) heating from room temperature to treatment temperature (190, 210 and 230 C) at a rate of 30 C/min; (ii) keeping at treatment temperature for 10 min; (iii) cooling to 60 C at a rate of -10 C/min. Figure S4. (a) first heating curve of samples to different temperature; (b) thermal 6

7 treatment of samples at different temperature for 10 min; (c) cooling curve of samples after thermal treatment. From the first heating curves (Figure S4a), one can clearly observe a glass transition temperature around 68 o C, and a cold crystallization peak at o C, which is in accordance with the WAXD results where there is a sudden increase of crystallinity at 100 ~ 110 o C (Figures 2 ~ 4). At o C and o C, there are two melting peaks for HCs. The small peak at lower temperature is a result of competition between the melting of HCs and the cold crystallization of SCs. Different with the sample heated to 190 and 210 o C, the sample heated to 230 o C shows a partial melting peak of SCs. Similar results were also detected in WAXD results, where SCs start to melt at a temperature higher than 211 o C (Figure 4). After 10 min isothermal treatment (Figure S4b), samples treated at different temperatures show different crystalline behaviors (Figure S4c). For the sample treated at 190 o C, the crystallization begins at a high temperature of 142 o C. This is consistent with WAXD results where the total crystallinity shows a sudden increase at around 140 C (Figure 2). For the sample treated at 210 o C, one can find a quite small cold crystallization peak, indicating that the HCs content in this sample is much smaller than the sample treated at 190 o C. This can be proved by the WAXD results (Figures 2 and 3) where there is no HCs after the cooling process. The peak showed in DSC may be ascribed to the crystallization of SCs. As for the sample treated at 230 o C, two crystalline peaks can be detected. This also agrees well with the WAXD results where 7

8 the crystallinity shows two noticeable increase at around 220 and 130 o C, respectively (Figure 4). 8

9 Figure S5. (a) 1D-WAXD profiles of the samples (a) at different temperatures during the heating process, (b) at different durations during the isothermal process, and (c) at different temperatures during the cooling process of thermal treatment at 250 C. Figure S6. X c-sc, X c-hc, and X c-total as a function of time during thermal treatment at 250 o C. Figure S6 shows the time dependent crystallinities (calculated by integration of the 1D-WAXD profiles as shown in Figures S5) during thermal treatment at 250 o C. 9

10 The heating process is almost the same as that of thermal treatment at 230 o C. Some feature temperature was labeled on the picture, and will not be described here for brevity. In the isothermal process, all SCs and HCs melt due to the elevated temperature. In the subsequent cooling process, SCs do not crystallize until the temperature drops to 179 C. In other words, an induction time is needed for the recrystallization of SCs because all SCs are melted and the template effect cannot be expected. This is in clear contrast to the crystalline behavior of the sample thermally treated at 230 C, where X c-sc exhibits a rapid increase as soon as the temperature begins to drop (Figure 4 in the manuscript). On basis of these results, a conclusion can be made that the surprisingly high crystallization temperature of the sample thermal treated at 230 o C attributes to the template effect of unmelted SCs. In agreement with the sample thermally treated at 190 and 230 o C, HCs presented in Figure S5 also show a high crystalline temperature of 146 C, 30 o C higher than that in neat PLLA melt. 1-2 As mentioned in the manuscript, the relatively high crystallization temperature of HCs results from SC s nucleation effect. Finally, after the whole thermal treatment, X c-sc, X c-hc, and X c-total reach 0.22, 0.15 and 0.37, respectively. In comparison with the results obtained after thermal treatment at 190, 210 and 230 C, X c-sc and X c-total are obviously lower here. This indicates that final crystallinities of thermally treated samples are dominated by thermal treatment temperatures, and the residual SCs make big differences in the crystallization of SCs during thermal treatment. 10

11 REFERENCES (1) Li, H. B.; Huneault, M. A. Effect of nucleation and plasticization on the crystallization of poly (lactic acid). Polymer 2007, 48, (2) Kulinski, Z.; Piorkowska, E. Crystallization, structure and properties of plasticized poly (L-lactide). Polymer 2005, 46,