Temperature and pH dual-responsive behavior of polyhedral oligomeric silsesquioxane-based star-blockcopolymer with poly(acrylic acid-block-N-isopropylacrylamide) as arms

Yu Bai,1 Jia Wei,1 Liping Yang,1 Chaobin He2* and Xuehong Lu1*

1School of Materials Science and Engineering

Nanyang Technological University

50 Nanyang Avenue, Singapore 639798, Singapore

Tel: +65-6790-4585;

Fax: +65-6790-9081;

E-mail:

2Institute of Materials Research and Engineering

3 Research Link, Singapore 117602, Singapore

Tel: +65-6874-8111;

Fax: +65-6872-0785;

E-mail:

Electronic Supplementary Material (ESM)


Fig. S11H NMR of the POSS ATRP initiator in DMSO-d6

Fig. S213C NMR of the POSS ATRP initiator in DMSO-d6

Fig. S31H NMR of POSS-PtBA8-b-PNIPAm11 in acetone-d6.

The Mn,NMR and DP of POSS-PtBA-b-PNIPAm were estimated by integration ratio of methine proton (s, 4.02) and methyl proton (s, 1.50) to aromatic and secondary amino proton (br, 6.7-9.0), which belong to PNIPAm segment, PtBA segment and the POSS initiator relatively. Due to the overlapping of NH from PNIPAm with the POSS initiator, the equivalent of 1H integration of PNIPAm should be subtracted from total integration of the broad peak 6.7-9.0. Similar method was used to estimate Mn and DP of other POSS-PtBA-PNIPAm copolymers

Fig. S41H NMR of POSS-PNIPAm13 in D2O.

The Mn,NMR and DP of POSS-PNIPAm were estimated by integration ratio of aromatic proton (br, 6.5-8.0) to methine proton (s, 3.80), which belong to the POSS-initiator and PNIPAm chains, relatively

Fig. S51H NMR of linear PNIPAm11 in D2O

The Mn,NMR and DP of linear PNIPAm were estimated by integration ratio of methylene proton (m, 4.05) to methine proton (s, 3.80), which belong to end group of the initiator and PNIPAm chains, relatively.


Fig. S6 ASEC curves of POSS-PNIPAm13 and the corresponding hydrolysis product with their Mn,ASEC indicated. To verify the star structure of POSS-PNIPAm, the sample was treated with HF and characterized by ASEC. The number of arms was estimated to be 6.6 by dividing Mn,ASEC of POSS-PNIPAm by that of its hydrolyzed product.

Fig. S7 The Tc of POSS-PAAc2-b-PNIPAm11, POSS-PAAc8-b-PNIPAm11, and POSS-PAAc4-b-PNIPAm25determined at 50% of total transmittance change as a function of pH.

Table S1Elemental analysis of the POSS ATRP initiator

Calculated value (%) / EA result (%) / Ratio of cal./EA
C / 40.96 / 39.78 / 1.03
H / 3.75 / 3.91 / 0.96
N / 4.78 / 4.44 / 1.08
Br / 27.30 / 25.22 / 1.08

Elemental analysis was conducted using the following method. For bromine analysis, ion chromatography instrumentation includes 818 IC Pump, 820 Separation Center, 830 Interface, 833 Liquid handling Unit, 732 Detector and 813 Compact Autosampler. The samples were combusted, and then collected in an absorbing liquid that was fed to ion chromatography. For carbon, hydrogen, nitrogen and sulphur (CHNS) analysis, instrumentation includes Elementar Vario Micro Cube. The samples were directly analyzed.

The calculated values are based on the data obtained from the octa-functionalized POSS ATRP initiator. The similar cal./EA ratios of nitrogen and bromine indicate the complete conversion of NH2 groups to 2-bromoisobutyl amide groups.

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