Experimental studies and mathematical modeling of the curing reaction of bioinspired copolymers

Figures & data

Figure 1. Copolymer chains showing crosslinking inter-chain (solid lines) and intra-chain interactions (dotted lines). The ESM model allows to discriminate them through a special matrix to better predict the curing kinetics.

Figure 2. GPC chromatograms. (A) Mixture of GPC standards (retention times: 21.36, 19.92 , 19.10, 17.42 min), (B) Washed solutions of VBT:VBA4 copolymer 0.4% AIBN (retention time 17.83 min) and (C) VBT:VBA4 copolymer 1.0% AIBN (retention time 19.36 min) at various irradiation times. Inset: Area under the GPC peak as function of irradiation time.

Table 1. Weight-average molecular weight and molecular weight distribution for two different VBT:VBA₄ copolymers.

VBT:VBA4 copolymer	RT (min)	Mp	Mn	Mw	PDI
0.4% AIBN	17.83	152,000	19,900	135,000	6.78
1.0% AIBN	19.36	32,500	20,000	68,000	3.40

Figure 3. UV–Vis spectra of the VBT:VBA₄ copolymer (0.4% AIBN) washed solution at various irradiation times. Inset: Evolution of the absorbance at 270 nm as function of irradiation time.

Figure 4. UV–Vis spectra of VBT:VBA₄ copolymer (0.4% AIBN) irradiated films toned with FD&C after the washing process at various irradiation times. Inset: Evolution of the absorbance at 501 nm as function of irradiation time.

Figure 5. UV–Vis spectra of the VBT:VBA₄ copolymer (1.0% AIBN) washed solution at various irradiation times. Inset: Evolution of the absorbance at 270 nm as function of irradiation time.

Figure 6. UV–Vis spectra of VBT:VBA₄ copolymer (1.0% AIBN) irradiated films toned with Erythrosine B after the washing process at various irradiation times. Inset: Evolution of the absorbance at 545 nm as function of irradiation time.

Table 2. Parameters used to evaluate the KM/ESM model.

Parameters	Values
VBT molecular weight	242.28 g mol^−1
VBA molecular weight	253.82 g mol^−1
[Ty]0	3 × 10^−5 L mol^−1
Functionality	4
Number average molar weight ()^a
0.4%AIBN	19,900 (Da)
1.0%AIBN	20,000 (Da)
Weight-average molar weight ()*
0.4%AIBN	135,000 (Da)
1.0%AIBN	68,000 (Da)
Distribution of reactive sites	Random
Kinetic constant	1030 L mol^−1 s^−1

^aInitial molecular weights experimentally obtained.

Figure 7. Molecular weight evolution as function of time (A, B) or extent of reaction (C, D) for the VBT:VBA₄ copolymer. (A and C) 0.4% AIBN, (B and D) 1.0% AIBN. Red dots indicate the experimental values found, while blue solid lines show the mathematical model predicted molecular weights for both copolymers. Dotted lines indicate the corresponding gel point times (t_gel) and gel points (α_gel).

Figure 8. Contribution from inter- and intra-chain crosslinking reactions, according to the mathematical model developed: (A) VBT:VBA₄ copolymer (0.4% AIBN) and (B) VBT:VBA₄ copolymer (1.0% AIBN).