Experimental
Reagents
Method for the synthesis of linear polyurethane coatings
Sample No. | Type of diisocyanate | Type of polyol (molecular weight) | Type of chain extender | Fluorine content (wt.%) | Type of solvent | Structural parameter | |
---|---|---|---|---|---|---|---|
κ
theor
|
κ
exp
| ||||||
1 | MDI | POG (2000) |
N-BDA | 0 | Chlorobenzene | 47.0 | 45.7 |
2 | MDI | POG (2000) |
N-BDA | 0 | 1,4-dioxane | 47.0 | 45.9 |
3 | MDI | POG (2000) |
N-PhDA | 0 | 1,4-dioxane | 47.4 | 45.1 |
4 | MDI | POG (2000) |
N-MDA | 0 | 1,4-dioxane | 49.3 | 47.3 |
5 | MDI | POG (2000) |
N-MDA | 0 | Chlorobenzene | 49.5 | 48.0 |
6 | MDI | POG (2000) | BD | 0 | 1,4-dioxane | 47.2 | 47.3 |
7 | MDI | POG (2000) | BD | 0 | Chlorobenzene | 46.7 | 35.6 |
8 | MDI | POG (2000) |
N-tert-BDA | 0 | 1,4-dioxane | 46.6 | 45.7 |
9 | MDI | POG (600) | TFBD | 5.70 | 1,4-dioxane | – | – |
10 | MDI | POG (600) |
N-MDA | 0 | 1,4-dioxane | 48.3 | – |
11 | MDI | POG (600) | HD | 0 | 1,4-dioxane | 41.0 | 40.0 |
12 | MDI | PEA (1000) |
N-MDA | 0 | 1,4-dioxane | 34.7 | 28.3 |
13 | MDI | PCL (2000) | BD | 0 | 1,4-dioxane | 22.9 | 22.3 |
14 | MDI | PCL (530) | TFBD | 6.01 | 1,4-dioxane | – | – |
15 | MDI | PCL (530) | BD | 0 | 1,4-dioxane | 25.8 | 29.0 |
16 | MDI | PTMO (1000) | BD | 0 | MEK | – | – |
17 | TDI | POG (2000) | BD | 0 | 1,4-dioxane | 48.1 | 49.1 |
18 | TDI | POG (600) | TFBD | 5.88 | 1,4-dioxane | – | – |
19 | TDI | POG (600) | BD | 0 | 1,4-dioxane | 46.4 | 41.7 |
20 | HDI | POG (2000) |
N-BDA | 0 | 1,4-dioxane | 49.8 | 47.2 |
21 | HDI | POG (2000) |
N-BDA | 0 | 1,4-dioxane | 49.8 | 46.8 |
22 | HDI | POG (2000) |
N-BDA | 0 | Chlorobenzene | 49.8 | 46.8 |
23 | HDI | POG (2000) | BD | 0 | 1,4-dioxane | 50.0 | 46.8 |
24 | IPDI | POG (2000) |
N-BDA | 0 | Chlorobenzene | 46.4 | 41.7 |
25 | IPDI | POG (2000) |
N-BDA | 0 | 1,4-dioxane | 46.4 | 43.4 |
26 | IPDI | POG (2000) |
N-MDA | 0 | Chlorobenzene | 47.3 | 43.5 |
27 | IPDI | POG (2000) | HD | 0 | 1,4-dioxane | 45.7 | 43.3 |
28 | IPDI | POG (2000) | HD | 0 | 1,4-dioxane | 45.7 | – |
29 | IPDI | POG (2000) | HD | 0 | 1,4-dioxane | 46.4 | 42.9 |
30 | IPDI | POG (2000) | BD | 0 | 1,4-dioxane | 46.5 | 43.6 |
31 | IPDI | POG (2000) | BD | 0 | Chlorobenzene | 46.5 | 42.7 |
32 | IPDI | POG (600) |
N-MDA | 0 | 1,4-dioxane | 46.7 | 35.6 |
33 | IPDI | POG (600) |
N-MDA | 0 | Chlorobenzene | 46.7 | 43.9 |
34 | IPDI | PEA (1000) |
N-MDA | 0 | 1,4-dioxane | 34.5 | 30.0 |
NMR spectroscopy
Type of structure | Based on NMR spectrum | Based on chemical formula (3) | |||||||
---|---|---|---|---|---|---|---|---|---|
Sample No. 2 | Sample No. 33 | Type of proton | Structural fragment derived | Number of protons | |||||
δ (ppm) | Integrations (conventional unit) |
δ (ppm) | Integrations (conventional unit) | Sample No. 2 | Sample No. 33 | ||||
Apolar structures |
I
i
| – | – | 0.77–0.88 | 1.6838 |
CH
3
–C | IPDI | – | 18 |
I
j + I
j′ + I
j′
| – | – | 0.93–1.24 | 2.8440 | C–CH
2
–C | IPDI | – | 12 | |
I
w
| 0.83–0.91 | 0.3591 | – | – |
CH
3
–(CH2)2–CH2–N– |
N-BDA | 3 | – | |
I
p + I
p’
| 1.23–1.40 | 0.5098 | – | – | CH3–(CH
2-
)
2
–CH2–N– |
N-BDA | 4 | – | |
I
c
| 1.41–1.64 | – | – | 0.7890 | CH3–(CH2-)
2
–CH
2
–N– |
N-BDA | – | 2 | |
– | – | 2.24–2.28 | 0.3053 |
CH
3–N |
N-MDA | – | 3 | ||
0.5·(I
b + I
b’ + I
m) | 3.32–3.4 | 12.5194 | 3.36–3.67 | 14.8291 | O–CH
2
–CH
2
–O (0.5 total amounts) |
N-BDA | – | 26 | |
O–CH
2
–CH
2
–O (0.5 total amounts) | POG 2000 | 88 | – | ||||||
I
d
| 3.62–3.64 | 0.7310 | – | – | Ar–CH
2
–Ar | MDI | 4 | – | |
I
k + I
l
| 7.08–7.69 | 2.222 | – | – | Ar | MDI | 16 | – | |
I
N
| 16.3413 | 20.4512 | 115 | 56 | |||||
Polar structures | 0.5·(I
b + I
b’ + I
m) | 3.32–3.4 | 12.5194 | 3.36–3.67 | 14.8291 |
–CH
2
–NH–CO– | IPDI | – | 4 |
>CH–NH–CO– | IPDI | – | 2 | ||||||
O–CH
2
–CH
2
–O (0.5 total amounts) | POG 600 | – | 26 | ||||||
O–CH
2
–CH
2
–O (0.5 total amounts) | POG 2000 | 88 | – | ||||||
CH3–N–CH
2
–
|
N-MDA | – | 2 | ||||||
C3H7–CH
2
–N |
N-BDA | 2 | – | ||||||
CH
3
–N–CH2– |
N-MDA | – | 3 | ||||||
I
e
| 3.93–4.02 | 0.8607 | 4.01–4.05 | 1.0000 | –CH2–O–CO–NH– | CH2 with urethan groups | 8 | 8 | |
I
x
| 9–10.5 | 0.4597 | 7.5–8.5 | 0.1479 | –NH–CO–O– | Urethan | 4 | 4 | |
I
P
| 13.8398 | 15.9773 | 102 | 49 | |||||
κ
theor (%) | 47.0 | 46.7 | |||||||
κ
exp (%) | 45.86 | 43.86 |
Contact angle
Surface free energy
Model measuring liquid | Surface free energy parameters (mJ/m2) | ||
---|---|---|---|
γ
L
|
\( \gamma_L^d \)
|
\( \gamma_L^p \)
| |
Water | 72.8 | 21.8 | 51 |
Formamide | 58.0 | 39 | 19 |
Diiodomethane | 50.8 | 48.5 | 2.3 |
Results and discussion
Chemical structures of synthesised polyurethanes
SFE of the films which were obtained from synthesised polyurethanes
The additive model for SFE versus polyurethane structure
-
A model in which additivity of the components in the function γ was assumed, hereinafter “additive model” (it was found more useful in the research presented in this paper), and
-
A model with the multiplicative function γ—“multiplicative model” (that was employed, e.g. in modelling the substitution effect during polymerisation, when the total kinetic equation constant is determined as a product of components which are dependent on the mer conversion degrees [17]).
Category of the independent variable | Type of substrate | The substrate attributed to independent variable | The value of the independent variable in this category |
---|---|---|---|
I
| Diisocyanate | MDI | 1 |
TDI | 2 | ||
HDI | 3 | ||
IPDI | 4 | ||
J
| Polyol | POG 2000 | 1 |
POG 600 | 2 | ||
PEA 1000 | 3 | ||
PCL 2000 | 4 | ||
PCL 530 | 5 | ||
PTMO 1000 | 6 | ||
K
| Chain extender | TFBD | 1 |
N-BDA | 2 | ||
N-PhDA | 3 | ||
N-MDA | 4 | ||
HD | 5 | ||
BD | 6 | ||
N-tert-BDA | 7 |
Sample No. | The value of the independent variable for i category | The value of the independent variable for j category | The value of the independent variable for k category | Estimation No. 1 | Estimation No. 2 | ||||
---|---|---|---|---|---|---|---|---|---|
\( \gamma_S^{\exp } \).(mJ/m2) |
\( \gamma_S^{\mathrm{estim}} \) (mJ/m2) | Relative error (%) |
\( \gamma_S^{\exp } \) (mJ/m2) |
\( \gamma_S^{\mathrm{estim}} \).(mJ/m2) | Relative error (%) | ||||
1 | 1 | 1 | 2 | 37.72 | 27.59 | 26.86 | Decline | ||
2 | 1 | 1 | 2 | 27.59 | 27.59 | 0.00 | 27.59 | 27.59 | 0.00 |
3 | 1 | 1 | 3 | 29.00 | 29.00 | 0.00 | 29.00 | 29.00 | 0.00 |
4 | 1 | 1 | 4 | 30.39 | 30.39 | 0.00 | 30.39 | 29,51 | 2.90 |
5 | 1 | 1 | 4 | 29.51 | 30.39 | 2.98 | 29.51 | 29,51 | 0,00 |
6 | 1 | 1 | 6 | 33.19 | 33.19 | 0.00 | 33.19 | 33.24 | 0.15 |
7 | 1 | 1 | 6 | 33.19 | 33.19 | 0.00 | 33.19 | 33.24 | 0.15 |
8 | 1 | 1 | 7 | 34.07 | 34.07 | 0.00 | 34.07 | 34.07 | 0.00 |
9 | 1 | 2 | 1 | 21.47 | 21.47 | 0.00 | 21.47 | 21.47 | 0.00 |
10 | 1 | 2 | 4 | 31.53 | 31.53 | 0.00 | 31.53 | 32.55 | 3.24 |
11 | 1 | 2 | 5 | 42.37 | 35.05 | 17.28 | 36.78 | 34.73 | 5.57 |
12 | 1 | 3 | 4 | 37.74 | 37.74 | 0.00 | 37.74 | 33.16 | 12.14 |
13 | 1 | 4 | 6 | 42.03 | 42.03 | 0.00 | 42.03 | 42.03 | 0.00 |
14 | 1 | 5 | 1 | 27.28 | 27.28 | 0.00 | 27.28 | 27.28 | 0.00 |
15 | 1 | 5 | 6 | 42.03 | 40.14 | 4.63 | 42.03 | 42.03 | 0.00 |
16 | 1 | 6 | 6 | 45.80 | 45.80 | 0.00 | 45.80 | 45.80 | 0.00 |
17 | 2 | 1 | 6 | 40.54 | 40.54 | 0.00 | 40.54 | 40.50 | 0.10 |
18 | 2 | 2 | 1 | 34.87 | 28.82 | 17.35 | 28.73 | 28.73 | 0.00 |
19 | 2 | 2 | 6 | 40.45 | 41.68 | 3.04 | 40.54 | 43.54 | 7.64 |
20 | 3 | 1 | 2 | 38.60 | 38.60 | 0.00 | 38.60 | 38.60 | 0.00 |
21 | 3 | 1 | 2 | 45.81 | 38.60 | 15.74 | Decline | ||
22 | 3 | 1 | 2 | 37.44 | 38.60 | 3.10 | 37.44 | 38.80 | 3.10 |
23 | 3 | 1 | 6 | 44.30 | 44.20 | 0.23 | 44.30 | 44.25 | 0.11 |
24 | 4 | 1 | 2 | 29.33 | 38.20 | 30.24 | Decline | ||
25 | 4 | 1 | 2 | 43.46 | 38.20 | 12.10 | 43.46 | 40.42 | 6.99 |
26 | 4 | 1 | 4 | 41.00 | 41.00 | 0.00 | 41.00 | 42.34 | 3.27 |
27 | 4 | 1 | 5 | 38.89 | 44.52 | 14.48 | Decline | ||
28 | 4 | 1 | 5 | 47.65 | 44.52 | 6.57 | 47.65 | 44.52 | 6.57 |
29 | 4 | 1 | 5 | 44.52 | 44.52 | 0.00 | 44.52 | 44.52 | 0.00 |
30 | 4 | 1 | 6 | 50.15 | 43.80 | 12.66 | 50.15 | 46.07 | 8.14 |
31 | 4 | 1 | 6 | 46.07 | 43.80 | 4.93 | 46.07 | 46.07 | 0.00 |
32 | 4 | 2 | 4 | 38.11 | 42.14 | 10.57 | 45.32 | 45.38 | 0.13 |
33 | 4 | 2 | 4 | 47.45 | 42.14 | 11.19 | 47.45 | 45.38 | 4.36 |
34 | 4 | 3 | 4 | 41.03 | 48.35 | 17.84 | 41.03 | 45.99 | 12.09 |
Sample No. | Substrates |
\( \gamma_S^{\exp } \) (mJ/m2) | ||
---|---|---|---|---|
Type of diisocyanate | Type of polyol (molecular weight) | Type of chain extender | ||
11 | 1 | 2 | 5 | 36.78 |
18 | 2 | 2 | 1 | 28.73 |
32 | 4 | 2 | 4 | 45.32 |
34 | 4 | 3 | 4 | 36.91a
|
The value of the independent variable |
A
|
B
|
C
|
---|---|---|---|
1 | 9.58 | 0.13 | 8.72 |
2 | 16.84 | 3.17 | 17.88 |
3 | 20.59 | 3.78 | 19.29 |
4 | 22.41 | 8.92 | 19.8 |
5 | 8.98 | 21.98 | |
6 | 12.69 | 23.53 | |
7 | 24.36 | ||
Const = 0.00 |
5
, and in particular to elastomer amorphous films or to those containing up to 20 % crystalline phase. The question is less important which solvent was employed to prepare the process solutions from which the polymer films were then formed.Analysis of effects of polyurethane structures on SFE values of obtained polymer films
-
When the raw materials needed for the production of linear polyurethanes are selected adequately, it is possible to obtain extensive structural changes which induce changes in SFE of polymer films within 18 to 50 mJ/m2. That is a very wide span of SFE which suggests that this method may be applicable in the production of various materials, from apolar films or coats to materials with considerable polarity.
-
The models show that the change in the diisocyanate component from i = 1 to 4 (Table 4) increases the SFE value by Δ = 10–15 mJ/m2 if the chain extender (Fig. 6) or polyol component remain the same. Samples No. 6, 17, 23 and 30 are examples of such polyurethanes; those were synthesised with the use of such diisocyanate feeds as POG 2000 polyol (j = 1) and BD chain extender (k = 6) which are in common practice. That makes an interesting observation which is in line with the calculated values of the κ theor parameter for the coats obtained from MDI, TDI and HDI (samples No. 6, 17, 23). The result for sample No. 30 (κ theor = 46.5 %) would suggest, on the other hand, that the IPDI-based coats should be more hydrophobic than found in SFE measurements.
-
The diagrams in Fig. 5 indicate that a change in the polyol component from j = 1 to j = 7 may increase the SFE values. Films produced with the use of polyesters PCL 530 or PEA 1000 (samples No. 15 and 12) are more polar and hydrophilic than their POG-2000 based counterparts (samples No. 6 and 5). The observed trend is completely in line with the values κ exp as found by the 1H NMR spectroscopic method. The κ exp parameters for poly(ester-urethanes) (samples No. 12 and 15) are much higher than those for more hydrophobic samples No. 5 and 6 (Table 1). However, no confirmation was obtained for the opinion, which was derived principally from the parameter κ theor, that the increasing molecular weight of polyol POG from 600 to 2,000 g/mol and PCL from 530 to 2,000 g/mol should cause a considerable increase in the SFE value. For example, the molecular weight values for polyester polyol (PCL; j = 4, 5) and for polyether polyol POG had no essential impacts on the SFE values in case of MDI-derived polyurethanes.
-
The most important effect on the chemical nature of polyurethane coats comes from the type of the chain extender. TFBD as a fluorine-containing reactant offered the most prominent effect within the tested substrates. That substrate contributes to the formation of coats with the definitely highest hydrophobicity (Fig. 5). Figure 5 indicates, that the use of MDI and POG 2000 is most favourable for the production of fluorine-containing hydrophobic coats. That is completely in line with our earlier observations [18]. When BD is substituted by HD or N-MDA, the SFE value will be lower by about Δ = 10-12 mJ/m2, and further shift to N-BDA (k = 2) will result in further decline of SFE by a similar value. On the other hand, relatively high SFE values for polyurethanes synthesised with N-tert-BDA result from strong dispersion interactions which are specific for a tertiary alkyl substituent. Those interactions increase the component \( \gamma_S^d \) (in Eq. 10) which has been confirmed in [19].