2 acrylamide 2 methylpropane sulfonic acid

(1) The benchmark cement used in this study was produced by China United Cement Group Co., Ltd., (Beijing, China), and its chemical composition and physical properties are shown in Table 2. (2) Isopentenyl polyoxyethylene ether (IPEG, M_W = 2400 g·mol⁻¹, average degree of polymerization was produced by Jiahua Chemical Co., Ltd. (Jinhua, China) acrylic acid (AA), methacrylic acid (MAA), sodium methacrylate sulfonate (SMS), 2-acrylamide-2-methylpropane sulfonic acid (AMPS), and itaconic acid (IA) were all of chemical purity and purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China) ammonium persulfate (APS) was produced by Jinan Fengle Chemical Co., Ltd. (Jinan, China) Sodium hexametaphosphate (SH) was produced by Jining Shunyida Chemical Technology Co., Ltd. (Jining, China) deionized water (W) was used throughout the experiments. The chemical composition and physical properties of the cement are shown in Table 2.

Photochromic acrylate derivatives of functional spiropyran groups (SPMA) were obtained from our previously published literature [14 (link)]. 2-Acrylamide-2-methyl propane sulfonic acid (AMPS, 98%), α-ketoglutaric acid (KA, BR), N, N′-methylene bis-(acrylamide) (MBAA, 99%), Tween 80 (CP), and sodium hydroxide (NaOH, AR) were supplied by Sinopharm Chemical Reagent Co., Ltd. Methyl acrylate (MA, 98.5%) and N-isopropylacrylamide (NIPAM, 98%) were purchased from Macklin Bio-Chem Technology Co., Ltd. (Shanghai, China). Phenyl bis(2,4,6-trimethylbenzoyl)-phosphine oxide (PBPO, 97%) was purchased from Aladdin Bio-Chem Technology Co., Ltd. (Shanghai, China). NIPAM was purified by recrystallization from hexanes. Deionized water (18.2 Ω-cm resistivity at 25 °C) was used in all experiments.