Page 57 - GHES-1-2

Global Health Econ Sustain Antimicrobial eco-friendly material

to the OH, likely attributed to absorbed moisture from the only difference being the intensity. Therefore, the presence
surroundings or strongly occluded water (Figure 3). of these two bands and overtones in all the spectra of grafted
In the analyzed grafted samples, with low grafting at samples proved that the grafting was effectively carried
6.2 g%, intermediate grafting at 32.4 g%, and high grafting out, involving the addition of the vinyl compound through
at 92.4 g%, the intensity of the OH bands increased around double bond addition onto the starch-based polymer matrix.
3394 cm . This signal could originate from BP as well as 3.3. Contact angle and swelling tests
-1
water, with the latter suggesting that the modified materials
are hydrophilic or even hygroscopic. Band assignments The contact angle of the water droplet was analyzed across
were further corroborated by the presence of an aromatic different samples (Figure 4). The contact angles measured
C-H band characteristic of poly(4VP) between 3200 cm at different time points (0, 1, and 3 min) exhibited no
-1
and 3000 cm , aromatic overtones between 2500 cm and significant variations, and only a subtle trend was observed
-1
-1
2000 cm , and a band between 1750 cm and 1500 cm based on the degree of grafting. Interestingly, the BP-g-
-1
-1
-1
corresponding to C=C in the ring (Table 1). These doublet 4VP (7.9 and 11.1 g%) samples displayed higher wetting
bands were congruent across all grafted samples, with the capabilities (contact angles of 88.2° and 81.8°, respectively)
compared to the pristine BP (0 g%) film, which exhibited
a higher contact angle of 100°, indicative of a hydrophobic
surface (Huang et al., 2022). While the wettability of BP-g-
4VP (18.5 and 22.8 g%) samples remained similar to that
of the original material, this characteristic can be attributed
to conformational effects and polymer chains size, taking
into account that poly(4VP) chains possess an aliphatic
part. Furthermore, as the grafting degree increased, the
surface exhibited greater hydrophilicity, ultimately reaching
the smallest angle of 80.1°, corresponding to BP-g-4VP
(65.7 g%).
Swelling of the pristine BP materials in water was minimal
(<2.5 s%). This property is suitable for its intended use as
a container for hot and cold drinks. The impermeability of
the BP material is another good feature for container use;
however, it limits its effectiveness in immobilizing organic or
inorganic compounds. Therefore, there is a need to enhance
its surface energy and hydrophilicity, as these properties are
often interconnected (Çaykara et al., 2020). In the swelling
test, the films grafted with 4VP, ranging from 7.2 ± 0.9 to
64.9 ± 1.1 g%, exhibited swelling percentages at 24 h ranging
from 5.9 ± 1.10% to 18.7 ± 2.1%, respectively. The maximum
swelling was typically reached at around 4 h. The hydrophilic
properties of these films varied from moderate to strong,
Figure 3. Fourier transmittance infrared spectra of pristine BP, poly(4VP), with water retention capacity depending on the graft%,
and BP-g-4VP. Note: BP* represents unwashed BP. particularly for grafting percentages lower than 30 g%

Table 1. Assignment of FTIR representative bands, wavenumber units are cm ‑1

Sample OH st CH st Aromatic overtones C=C CH b
Pristine BP* 3338 2950, 2917, 2840 - - 1453,1375
Pristine BP 3300 2950, 2917, 2850 - - 1434, 1375
Poly (4VP) 3246 3106, 2941 2323, 2186, 2051 1659 1494, 1413
BP-g-4VP (6.2 g%) 3394 2950, 2918, 2850 2323, 2162, 2043 1597 1433, 1375
BP-g-4VP (32.4 g%) 3320 2950, 2918, 2850 2229, 2184, 2162 1596 1449, 1376
BP-g-4VP (96.4 g%) 3395 3024, 2919, 2851 2324, 2185, 2014 1595, 1556 1413, 1376
-1
Notes: *In the unwashed BP, there is a band in the range 1738 – 1592 cm , possibly from plasticizer. Notes: Stretching (st) and bending (b).

Volume 1 Issue 2 (2023) 5 https://doi.org/10.36922/ghes.1251