Self-Assembly Supramolecular Systems Based on Guanidinium Salts Modified Hyperbranched Polyamidoamine and Cationic Acrylamide Copolymers

Herein, novel hyperbranched polyamidoamine guanidinium salts (GS-h-PAMAM) and two cationic acrylamide copolymers P(AM-DAC-ABSM) and P(AM-DAC-AMTU) were successfully prepared. Then, self-assembly supramolecular systems were synthesized by directly mixing GS-h-PAMAM with copolymers in aqueous solution, and the mechanism of the self-assembly process was speculated. FT-IR, NMR, and SEM were used for structural confirmation. Furthermore, the excellent solution properties revealed that the supramolecular systems had potential application in clay hydration inhibitors. More importantly, utilizing functionalized hyperbranched polyamidoamine in the synthesis self-assembly supramolecular systems was an effective strategy for expanding their application fields and developing new functional materials, providing a powerful reference for the next study.

. The synthetic route of ABSM.

Preparation and characterization of monomer AMTU
Preparation of monomer AMTU. Methyl isothiocyanate (7.21 g, 0.10 mol), triethylamine (30 mL) and 30 mL acetonitrile were added into a 250 mL three-necked round bottom flask with a magnetic stir bar, condenser and thermometer. After completely dissolved, allylamine (6.24 g, 0.11 mol) was slowly dropped into the mixture, then raised the temperature to 60°C. After refluxed for 7 h, the crude product was washed repeatedly with diethyl ether, filtered, evaporated, a white powder product 1-allyl-3-methylthiourea AMTU was obtained in 78.1% yield.

Rate of anti-swelling determination method
The rate of anti-swelling of polymer solution to bentonite was determined by centrifugation method, which according to Chinese oil and gas industry standard SY/T 5971-1994 "Performance evaluation method of clay stabilizer for water injection", the details was as follows: a graduated 10.0 mL centrifuge tube with 0.50 g dried bentonite sample, 10.0 mL polymer solution was added and stirred evenly, let it stand at a constant temperature for 2 h. Then the sample was centrifuged at 1500 r/min for 15 min, and the swelling volume of bentonite was recorded as V1. The swelling volumes of bentonite in pure water V2 and in kerosene V0 were measured via the same method, the rate of anti-swelling of the polymer solution was calculated by the [Eq. (S1)]. (S1) wherein B was the rate of anti-swelling of the polymer solution; V0 was the swelling volume of bentonite in kerosene, mL; V1 was the swelling volume of bentonite in pure water, mL; and V2 was the swelling volume of bentonite in the polymer solution, mL.
According to the results of previous experiments, The V1 and V0 value of the bentonite used in this paper (montmorillonite) were 3.2 and 0.6, respectively.   Figure S7. The FT-IR of (a) P(AM-DAC-ABSM) and (b) P(AM-DAC-AMTU).

Composition determination
Due to the long molecular chain length and complex structure of the copolymers, conventional characterization methods were difficult to determine the structure. In order to determine whether the functional monomer successfully entered the copolymer backbone and determined the composition of the copolymer, the composition of the copolymers were determined by high performance liquid chromatography. The AM, DAC, and ethanol used to purify the polymer were measured, respectively, and the test  Table S1 and S2.
wherein α was the monomer conversion rate (%); W was the monomer raw charge quality (g); A was the monomer peak area in the chromatogram of the ethanol used for purifying the polymer; C0/A0 was the reciprocal of the slope of the monomer standard curve; V was the total volume (L) of ethanol used to purify the polymer.

Intrinsic Viscosity Measurement
Intrinsic   Figure S9. The TG-DTG of (a) P(AM-DAC-ABSM) and (b) P(AM-DAC-AMTU).  a All data were the average of three measurements with an error of ±0.1.

Test methods on rate of anti-swelling after different scouring times
The basic method for testing the rate of anti-swelling was according to the steps in "3. Rate of anti-swelling determination method". After centrifugation, the supernatant was poured out, 10.0 mL of deionized water was added, stirred evenly, and allowed to stand for 2 h. The rate of anti-swelling was tested via the same method, repeated the above steps 4 times and recorded the results for each time.

Test methods on cuttings recovery rate
The cuttings recovery rate of different solutions system was determined according to the Chinese oil and gas industry standard SY/T 5613-2000 "Physical and Chemical Properties Test Method for Mud Shale", the details was as follows: grinded the core, through a 40 mesh sieve, dried at 105°C for 8 h, then cooled to room temperature.
Weighed 50.0 g (accurate to 0.1 g) of dried cuttings and filled it in a high temperature tank with 350.0 mL different solutions, rolling in a roller furnace at 80°C for 16 h. After the hot rolling was completed, took out the high temperature tank and cooled to room temperature, poured the sample into a 40 mesh sieve and wetted it with tap water for 1 min. The remaining cuttings samples were placed at 105°C oven for 6 h, cooled and weighed, and recorded as M1, the first cuttings recovery rate R1 was calculated via [Eq.
(S5)]. The cuttings were again subjected to the same method as in the high temperature tank containing 350.0 mL of deionized water, and M2 was measured according to the above procedure, and the second cuttings recovery rate R2 was calculated via the [Eq. (S6)].
wherein R1 was the first cuttings recovery rate, %; M1 was the residual mass after the first hot rolling of the cuttings, g; R2 was the second cuttings recovery rate, %; M2 was the residual mass after the second hot rolling of the cuttings, g; M0 was the initial mass of cuttings, 50.0 g.

Test methods on rheological behavior of solution system
Polymer (0.2 wt%) of rheological behavior was conducted by a HAAKE MARS III rheometer (HAAKE, Germany) at an appropriate temperature.

Shear thinning and shear recovery test
Shear thinning of 2000 mg/L polymer solution was measured via a rotation rheometer (Haake RheoStress 6000, Germany) with a shear rate range of 7.34-510 s -1 at 30 ± 0.1 o C, the shear recovery was performed with stepped shear rate 7.34-510-7.34 s -1 under the same conditions as others.

Viscoelasticity
Viscoelasticity of polymer solution (2000 mg/L) was obtained via measuring the elastic modulus (G') and viscous modulus (G") with particular stress (1 Pa) at 30 o C in the frequency scanning range: 0.01-10 Hz. The behavior of the viscoelasticity was described via [Eq. (S7 and S8)]).
wherein G was stress relaxation modulus, λ was relaxation time, and ω was angular frequency.