Dual Physically Cross-Linked Hydrogels with High. Stretchability, Toughness and Good Self-

Transcription

1 Dul Physiclly Cross-Linked Hydrogels with High Stretchility, Toughness nd Good Self- Recoverility Yng Hu,, Zhengshn Du, Xioln Deng, To Wng, Zhuohong Yng, Wuyi Zhou,*, Choyng Wng*, Reserch Institute of Mterils Science, South Chin University of Technology, Gungzhou 5164, Chin Institute of Biomterils, College of Mterils nd Energy, South Chin Agriculturl University, Gungzhou 51642, Chin Preprtion of net Fe 3+ cross-linked hydrogels. The net Fe 3+ cross-linked PAm-co-Ac hydrogel (nmed s Fe 3+ -hydrogels) ws prepred s the following procedure. Firstly, the monomers Am (3. mol L -1, with respect to the volume of wter) nd Ac (15%, molr rtio of Ac/Am) were dded into wter, nd then the system ws stirred for 3 min in n ice-wter th. Afterwrds, given mount of FeCl 3 6H 2 O ws dded, followed y stirring for 2 h t room temperture. After the system ws degssed with nitrogen gs for 1 min, the inititor APS (.1 wt%, with respect to the wter weight) nd the ctlyst TEMED (2 ul) were dded under ultrsoniction t ice-wter temperture. Afterwrds, the resulting solution ws trnsferred into S1

2 Stress (kp) cylindricl glss tues, which were seled with plstic wrps nd then plced t room temperture for 16 h to form Fe 3+ -hydrogels. Herein, the Fe 3+ contents used to prepre the Fe 3+ - hydrogels were.3,.6, 1.2 nd 2.4 mg g -1 (with respect to the totl mss of wter nd monomers), respectively. Determintion of the Fe 3+ content trpped in DPC hydrogels. The Fe 3+ content in the DPC hydrogel ws determined using Hitchi Z2 tomic sorption spectrometer. At first, 1 g of DPC hydrogel smples ws immersed in 1 ml of 1 mol L -1 HCl solution to extrct out Fe 3+ from the hydrogel network. And then the Fe 3+ content in HCl solution ws mesured y tomic sorption spectroscopy, which could e used to clculte the Fe 3+ content extrcted from hydrogel network, nd otin the Fe 3+ content trpped in the hydrogel network Figure S1. The mplified figure of the typicl tensile stress-strin profile of m-hydrogel shown in Figure 3. S2

3 Stress (kp) mg g -1.6 mg g mg g -1 Figure S2. Typicl tensile stress-strin profiles of Fe 3+ -hydrogels prepred t different Fe 3+ contents (with respect to the totl mss of wter nd monomers). As shown in Figure S2, with the increse of the Fe 3+ content from.3 to.6 mg g -1, the tensile strength nd frcture strin of Fe 3+ -hydrogels oviously enhnced. However, further incresing the Fe 3+ content up to 1.2 mg g -1 nd 2.4 mg g -1 resulted in the clerly decrese in the mechnicl properties. Especilly, the Fe 3+ -hydrogel prepred t 2.4 mg g -1 of Fe 3+ content ws too wek to determine its tensile mechnicl properties. The ove results indicted tht Fe 3+ could ct s crosslinker to initite the free rdicl polymeriztion nd lso displyed negtive influence on the polymeriztion. According the literture reported y Zhong, 1 the high Fe 3+ content could led to the decrese in the moleculr weight of the polymer gels. Thus mechnicl properties of Fe 3+ - hydrogels prepred t 1.2 nd 2.4 mg g -1 of Fe 3+ contents degrded, which could e scried to high cross-linking density nd the negtive influence of Fe 3+ on the polymer moleculr weight. Herein, the tensile strength nd frcture strin of the optiml Fe 3+ -hydrogels were c. 21 kp nd 61%, respectively S3

4 Stress t 8% strin (MP) Stress (MP) Elstic modulus (kp) c Figure S3. Digitl photogrphs of () m-hydrogel, () d-hydrogel nd (c). 4 m-hydrogel d-hydrogel c m-hydrogel d-hydrogel m-hydrogel d-hydrogel Figure S4. () Typicl compressive stress-strin profiles, () Elstic modulus nd (c) compressive stress t 8% strin of m-hydrogel, d-hydrogel nd. S4

5 m (D-hydroglel) /m (d-hydrogel) (%) cly concentrtion (wt%) Figure S5. The effect of the cly concentrtion on the mss rtio of hydrogel fter immersing d- hydrogel in wter for 48 h to otin. S5

6 Fe 3+ content (mg g -1 ) Fe 3+ content (mg g -1 ) Immerse time (h) Ac/Am molr rtio Figure S6. () The effect of the immerse time on the Fe 3+ content (the mss of Fe 3+ with respect to the mss of hydrogel) extrcted y 1 mol L -1 HCl solution from the prepred t the Ac/Am molr rtio of 15%. () The effect of Ac/Am molr rtio on the Fe 3+ content trpped in the network. Herein, it ws seen from Figure S6 tht the Fe 3+ content extrcted y HCl solution from the D- hydrogel prepred t the Ac/Am molr rtio of 15% oviously incresed when the immerse time incresed from.25 h to 8 h, nd then leveled off up to 16 h nd 24 h immersion. Thus, we determined the Fe 3+ content trpped in the s with different Ac/Am molr rtios fter immersing the hydrogels in 1 mol L -1 HCl solution for 24 h. As oserved from Figure S6, incresing the Ac/Am molr rtio resulted in the grdul enhncement of the Fe 3+ contents (the mss of Fe 3+ ions with respect to the mss of hydrogel) trpped in the s, which indicted tht the crosslinking density of the networks incresed with the increse of the Ac/Am molr rtio. S6

7 m (d-hydroglel) /m (m-hydrogel) (%) m (D-hydroglel) /m (d-hydrogel) (%) Elstic modulus (MP) Toughness (MJ m -3 ) Stress (MP) Stress (MP) mol/l 3. mol/l 4.5 mol/l 6. mol/l mol/l mol/l 4.5 mol/l mol/l d-hydrogel c d-hydrogel 45 3 d Am concentrtion (mol L -1 ) Am concentrtion (mol L -1 ) Figure S7. Stress-strin profiles of () d-hydrogels nd () s prepred t different Am concentrtions. (c) Elstic modulus nd (d) toughness of d-hydrogels nd s prepred t different Am concentrtions Fe +3 concentrtion (mol L -1 ) Fe +3 concentrtion (mol L -1 ) Figure S8. () The mss rtios of the m-hydrogels fter tretment y Ferric solution for 3 h (dhydrogel). () The mss rtios of hydrogel fter immersing d-hydrogel in wter to form D- hydrogel. S7

8 Stress (MP) Stress (MP) h 6 h 3 h 9 min.5 3 min Strin(%) min 6 h 9 h 3 h.5 3 min Figure S9. () Stress-strin profiles of () d-hydrogels nd () s with different immersing times in FeCl 3 queous solution. REFERENCES [1] Zhong, M.; Liu, Y. T.; Liu, X. Y.; Shi, F. K.; Zhng, L. Q.; Zhu, M. F.; Xie, X. M. Dully cross-linked single network poly(crylic cid) hydrogels with superior mechnicl properties nd wter sorency. Soft Mtter, 216, 12, S8