Gpc 8020

Molecular weight was measured using a GPC system (GPC-8020, Tosoh, Tokyo, Japan). A TSK guard column, and two TSK GEL α-M columns were used. The mobile phase was DMF containing 10 mM LiCl with a flow rate of 1.0 mL/min. Samples were dissolved in mobile phase (0.5 mg/mL). The column temperature was 40 °C. Calibration was performed using polyethylene glycol standards (Tosoh) (Figure S1).

The T/H extracts from rubber synthesizing assay were subjected to gel permeation chromatography (GPC) which was carried out with Tosoh GPC-8020 (Tosoh, Tokyo, Japan), equipped in tandem with a series of a TSK gel GPC columns, TSKguardcolumn MP(XL) and two Multipore H_XL-M columns (Tosoh). The chromatography was carried out at 40˚C using THF as eluent, at a flow rate of 1 ml/min. The eluate was monitored by a refractive index detector RI-8020 (Tosoh) and subsequently collected as 1-ml fractions (1-min interval) to measure radioactivity. The molecular mass of the reaction products were estimated by comparison with the retention times of commercially available polyisoprene standards (Mw: 999000, 110000, and 9600, Polymer Standards Service, Mainz, Germany).

The phase transition behavior of the prepared polymers was observed by temperature dependent transmittance change of the polymer solution. Polymer solution was prepared by dissolving the polymer in PBS at a concentration of 5 mg/mL. The transmittance of the polymer solution at 500 nm was measured using a UV-Vis spectrometer (V-630, JASCO, Tokyo, Japan) whilst heating the polymer solution at 0.1 °C/min. The lower critical solution temperature was defined as the temperature at which 50% transmittance was observed.
The molecular weight of the polymer was obtained by GPC (GPC-8020, Tosoh, Tokyo, Japan) using two serially connected TSK-Gel α-M columns (Tosoh, Tokyo, Japan). The columns were calibrated using PEG standards. The mobile phase was DMF containing 10 mM of LiCl. The molecular weight of P(NIPAAm-co-DMAPAAm) was also determined by ¹H NMR. The sample solution was prepared by dissolving copolymers in CDCl₃ at a concentration of 15 mg/mL. ¹H NMR spectra were obtained using a nuclear magnetic resonance spectrometer (Varian INOVA 500, Varian, Palo Alto, CA, USA). The molecular weight of P(NIPAAm-co-DMAAm) was also obtained by titration molecular weight. The polymer (25 mg) was dissolved in 2 mL of pure water. Titration of the terminal carboxyl group of the polymer was performed using 0.0025 mol/L NaOH solution.