Interfacial Effects on the Crystallization and Surface Properties of Poly(L-Lactic Acid)

Interfacial Effects on the Crystallization and Surface Properties of Poly(L-lactic acid) Ultrathin Films

Akihiro Udagawa†, ToshinoriFujie§, YukoKawamoto§, Akihiro Saito§, ShinjiTakeoka§ and ToruAsahi*,†,§

†Department of Advanced Science and Engineering, Graduate School of Advanced Science and Engineering, Waseda University, 3-4-1Okubo, Shinjuku-ku, Tokyo, 169-8555 (Japan); §Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480 (Japan)

Macintosh SSD Users kyohyo pro2 Desktop conc thickness eps

Figure S1.Thickness profile of PLLA nanosheets as a function of PLLA concentrations.

Macintosh SSD Users kyohyo pro2 Desktop nanosheet Figures PJ revise Figure Figure S7 png

Macintosh SSD Users kyohyo pro2 Desktop XRD en ai Figure S3shows the results of XRD. Annealed PLLA nanosheets show the peaks at ca. 16.5˚ attributedto the crystalline of PLLA, while non-annealed PLLA nanosheets shows no peaks. Accordingly PLLA nanosheets were crystallized by thermal annealing above Tg. In comparison with two conditions of annealing temperature on the similar thickness of PLLA nanosheets, the peak value of 120oC annealed PLLA nanosheet is higher than that of 80oC. Hence, the crystallinity of 120oC annealed PLLA nanosheet is higher than that of 120oC, thus the crystallinity of PLLA nanosheets can be controlled by annealing temperature. And in both annealing conditions, the peak areas were increasing depending on the increment of their thickness; therefore it suggested that internal bulk region also crystallized(Figure S4).

Figure S3.XRD patterns of PLLA nanosheets with the thickness of 60nm, annealed at three conditions.

Macintosh SSD Users kyohyo pro2 Desktop XRD 80 eps

Figure S4.XRD pattern of PLLA nanosheet annealed at 80oC with various thickness.

Macintosh SSD Users kyohyo pro2 Desktop Voigt example eps An example of the drawing for fitting the XRD data of PLLA nanosheet with 500 nm thickness (annealed at 120oC, 2 h) to Voigt function is shown in Figure S5.

Figure S5. Fitting pattern of XRD spectrum of PLLA nanosheet with the thickness of 500 nm, annealed at 120oC.

Macintosh SSD Users kyohyo pro2 Desktop nanosheet Figures PJ revise Figure Figure S5 png To investigate the effect of PVA on the crystallization of PLLA, we observed the surface morphology of the PLLA nanosheet fabricated with the PVA layer on top, which was annealed at 80˚C for 2 hours (Figure S6. (a)). As shown in Figure S6. (b), the height image of air-side surface of PLLA nanosheet with 60 nm thickness, it looks almost similar to the image of PLLA nanosheet fabricated by conventional method shown in Figure 2. In addition, the phase image shown in Figure S6 (c) suggests that there should belittlePVA exhibitingdifferent hardness from PLLA. From these results, it was suggested that the thin PVA layer had no effect on the crystallization of PLLA. Moreover, Zhang et al. reported for PS thin films on Si substrate that long-range interaction from Si substrate beneath the thin SiO2 layer can affect the thermal molecular mobility.1 This report may support our consideration that interaction from substrate can affect PLLA beyond PVA layer.

Reference

1. Zhang, C., Fujii, Y. & Tanaka, K. Effect of Long Range Interactions on the Glass Transition Temperature of Thin Polystyrene Films. ACS Macro Lett. 1, 1317–1320 (2012).