Supporting information for

Unravelling the interactions between biomedical thermoresponsive

polymer and biocompatible ionic liquids

Reddicherla Umapathi1, Imran Khan1,2,3, João A. P. Coutinho2*, Venkatesu Pannuru1*

1Department of Chemistry, University of Delhi, Delhi 110 007, India2CICECO - Aveiro Institute of Materials, Chemistry Department, University of Aveiro, 3810-

193 Aveiro, Portugal3Department of Chemistry, College of Science, Sultan Qaboos University, PO Box 36, PC

123, Muscat, Oman

*Corresponding author. Tel.: +91-11-27666646-142

E-mail address: jcoutinho@ua.pt (João A.P. Coutinho)

venkatesup@hotmail.com, pvenkatesu@chemistry.du.ac.in (P. Venkatesu)

Instrumentation and measurements

UV-Visible absorption spectra measurements

Ultraviolet-visible (UV-vis) absorption spectra of the PNIPAM were recorded from 190 to

800 nm by means of a double beam UV-visible spectrophotometer (UV-1800, Shimadzu Co.,

Japan) at room temperature. An aliquot of sample solution was transferred uniformly into the

quartz cell of 1 cm path length. The spectrophotometer had matched quartz cells, with

spectral bandwidth of 1 nm and wavelength accuracy of ±0.3 nm with automatic wavelength

correction.

Fluorescence intensity measurements

Fluorescence intensity measurements of ANS in aqueous PNIPAM solution in the

absence and in the presence of ILs were carried out using a Cary Eclipse fluorescence

spectrophotometer (Varian optical spectroscopy instruments, Mulgrave, Victoria, Australia)

with an intense Xenon flash lamp as light source. All intensity measurements were performed

at excitation wavelength (λex) of 510 nm. Emission spectra were recorded with slit width of

5/5 nm and the PMT voltage of 720 V. Scan speed was kept at 1200 nm min -1. Quartz cuvette

(QC) containing sample was placed in multi cell holder, which is electro-thermally controlled

at precise temperature by a peltier. The temperature control of the peltier thermostated cell

holders is extremely stable over time, with a typical precision of ±0.05 K. prior to measuring

each sample solution was left for 10-15 min undisturbed at all temperatures to attain

thermodynamic equilibrium.

Hydrodynamic diameter (dH) measurements

Hydrodynamic diameter (dH) of PNIPAM aggregates in the absence and in the presence

of ILs were measured by dynamic light scattering (DLS) using a Zetasizer Nano ZS90

(Malvern Instruments Ltd., UK), equipped with He-Ne (4 mW, 632.8 nm). In built

thermostatic sample chamber enables to maintain the desired temperatures within a

temperature range of 2-90 0C with a great accuracy. This instrument measures the movement

of particles under Brownian motion and converts this motion into size (dH) by using the

Stokes-Einstein equation as follows

dH=¿ kT

6πηD¿ (1)

where k is the Boltzmann’s constant, T is absolute temperature, η is viscosity, and D is

diffusion coefficient. All data were obtained by the instrumental software. All the reported

values are an average of three measurements of the sample.

Viscosity (η) measurements

The viscosities (η) of all the samples are measured using a sine-wave vibro

viscometer (model SV-10, A&D Company Limited, Japan) with an uncertainty of 1%. The η

of sample solutions was collected in the wide temperature range by using a circulating

temperature control water bath (LAUDA alpha 6, Japan) with accuracy of temperature of

±0.02 K. The sine-wave vibro viscometer equipped with two gold sensor plates measures the

η of sample by detecting the driving electric current necessary to resonate the two sensor

plates at a constant frequency of 30 Hz and amplitude of less than 1 mm. All η measurements

of the sample were collected at heating rate of 2 K/h after allowing to the thermodynamic

equilibrium. All of the viscometer accessories were cleaned and dried before performing each

measurement.

Fig. S1. Fluorescence emission spectra of ANS (2 X 10-5 M of ANS concentration) in

PNIPAM aqueous solution (6 mg/mL of PNIPAM concentration) without IL (black line) and

with presence of ILs (a) 10 mg/mL ILs, (b) 15 mg/mL at 25 0C. ILs: IL free (Black line), [Ch]

[Ac] (red line), [Ch]Cl (green line), [Ch][DHCit] (blue line) and [Ch][Bit] (cyan line).

Fig. S2. Temperature dependent Fluorescence emission spectra of ANS (2 X 10-5 M of ANS

concentration) in PNIPAM aqueous solution (6 mg/mL of PNIPAM concentration) without

IL (black line) and with presence of ILs (a) 10mg/mL ILs, (b) 15 mg/mL in the temperature

range of 25-40 0C. ILs: IL free (Black line), [Ch][Ac] (red line), [Ch]Cl (green line), [Ch]

[DHCit] (blue line) and [Ch][Bit] (cyan line).

Fig. S3 Hydrodynamic diameter, of PNIPAM (6 mg/mL of PNIPAM concentration) aqueous

solution without IL (black color line) and with presence of ILs (a) 10mg/mL ILs, (b) 15

mg/mL in the temperature range of 25-40 0C. ILs: IL free (Black line), [Ch][Ac] (red line),

[Ch]Cl (green line), [Ch][DHCit] (blue line) and [Ch][Bit] (cyan line).

Fig. S4 Temperature dependent viscosity of PNIPAM (6 mg/mL of PNIPAM concentration)

aqueous solution without (black color line) and with presence of IL (a) 10 mg/mL, (b) 15

mg/mL in the temperature range of 25-40 0C. ILs: IL free (Black line), [Ch][Ac] (red line),

[Ch]Cl (green line), [Ch][DHCit] (blue line) and [Ch][Bit] (cyan line).