PA6 substrates were prepared as follows: in their unmodified state, as obtained from the manufacturer, or as prepared in-house; washed state, following washing in DI water prior to reactions; or their incubated state where PA6 substrates were incubated in reaction buffer under the same conditions as an enzymatic assay from 40-70 °C (Supplementary Fig. 3 ). Substrates were also assessed after enzyme reactions, following incubation with 1 µM NylCK-TS at 60 °C for 10 days. Prior to analysis, other than the unmodified substrates, all samples were rinsed in DI water to remove salts and enzymes. All substrates were then dried for 4 h at 50 °C to remove residual water. The thermal stability of nylon samples was assessed by thermogravimetric analysis (TGA) using a Discovery TGA 5500 (TA Instruments). For each run, 6-10 mg of polymer sample was placed in a platinum TGA pan. Samples were heated under nitrogen from ambient temperature to 200 °C at a rate of 4 °C/min, then from 200 °C to 800 °C at a rate of 20 °C/min. TRIOS software (TA Instruments, v5.1.1.46572) was used to characterize the onset temperature of polymer degradation (TD,50) and the weight percent of residual char at 800 °C. The mass percent loss and temperature of the derivative maximum were determined for each mass loss event.
Differential scanning calorimetry (DSC) was used to measure the thermal properties and crystallinity of unmodified and treated nylons. Samples were dried at 40 °C for 24 h in a vacuum oven to remove absorbed water immediately prior to analysis60 (link). DSC measurements were performed on a Discovery X3 Differential Scanning Calorimeter (TA Instruments) using 4-8 mg of sample in hermetically sealed aluminum pans (DSC Consumables). Each DSC run consisted of two heating and cooling cycles between 0 °C and 290 °C at a rate of 10 °C/min with 5 min isothermal holds between each heating and cooling ramp. The glass transition temperature (Tg), melting temperature (Tm), enthalpy of melting (ΔHm), crystallization temperature (Tc), temperature of cold crystallization (Tc), and enthalpy of cold crystallization (ΔHc) for each sample was determined when applicable with TRIOS software (Universal Analysis, v5.4.0.300). Integration bounds and baselines were determined following the procedure described by Khanna and Kuhn60 (link). The following equation was used to calculate percent crystallinity, where ΔHm°, the reference enthalpy of melting, is 230.1 J/g for nylon-6114 .
Gel permeation chromatography (GPC) with multi-angle light scattering (MALS) and differential refractive index (dRI) detectors was used to measure the weight average molar mass (Mw), number average molar mass (Mn), and molar mass dispersity (Đ) values of PA6 samples. Samples were dissolved in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) with 20 mM of sodium trifluoroacetate (NaTFAc) at a concentration of ~ 5 mg/mL, then filtered through 0.2 µm PTFE syringe filters (Agilent). GPC was conducted using a 1260 Infinity II LC system (Agilent), three PL HFIPgel 250 × 4.6 mm columns, and a matching guard column (Agilent). HFIP supplemented with 20 mM NaTFAc was used as the mobile phase at a flow rate of 0.35 mL/min. Due to HFIP’s viscosity, the HPLC column oven was heated to 40 °C to decrease column backpressure. An Optilab T-Rex refractive index detector (Wyatt Technology) and miniDawn TREOS MALS detector (Wyatt Technology) were attached in line. Mn, Mw, and Đ were calculated with ASTRA (Wyatt Technologies, version 8.2.0), using 0.2375 as the dn/dc of PA6 in HFIP (Wyatt Technologies Database of dn/dc values).
Differential scanning calorimetry (DSC) was used to measure the thermal properties and crystallinity of unmodified and treated nylons. Samples were dried at 40 °C for 24 h in a vacuum oven to remove absorbed water immediately prior to analysis60 (link). DSC measurements were performed on a Discovery X3 Differential Scanning Calorimeter (TA Instruments) using 4-8 mg of sample in hermetically sealed aluminum pans (DSC Consumables). Each DSC run consisted of two heating and cooling cycles between 0 °C and 290 °C at a rate of 10 °C/min with 5 min isothermal holds between each heating and cooling ramp. The glass transition temperature (Tg), melting temperature (Tm), enthalpy of melting (ΔHm), crystallization temperature (Tc), temperature of cold crystallization (Tc), and enthalpy of cold crystallization (ΔHc) for each sample was determined when applicable with TRIOS software (Universal Analysis, v5.4.0.300). Integration bounds and baselines were determined following the procedure described by Khanna and Kuhn60 (link). The following equation was used to calculate percent crystallinity, where ΔHm°, the reference enthalpy of melting, is 230.1 J/g for nylon-6114 .
Gel permeation chromatography (GPC) with multi-angle light scattering (MALS) and differential refractive index (dRI) detectors was used to measure the weight average molar mass (Mw), number average molar mass (Mn), and molar mass dispersity (Đ) values of PA6 samples. Samples were dissolved in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) with 20 mM of sodium trifluoroacetate (NaTFAc) at a concentration of ~ 5 mg/mL, then filtered through 0.2 µm PTFE syringe filters (Agilent). GPC was conducted using a 1260 Infinity II LC system (Agilent), three PL HFIPgel 250 × 4.6 mm columns, and a matching guard column (Agilent). HFIP supplemented with 20 mM NaTFAc was used as the mobile phase at a flow rate of 0.35 mL/min. Due to HFIP’s viscosity, the HPLC column oven was heated to 40 °C to decrease column backpressure. An Optilab T-Rex refractive index detector (Wyatt Technology) and miniDawn TREOS MALS detector (Wyatt Technology) were attached in line. Mn, Mw, and Đ were calculated with ASTRA (Wyatt Technologies, version 8.2.0), using 0.2375 as the dn/dc of PA6 in HFIP (Wyatt Technologies Database of dn/dc values).
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