8
1 Introduction to PVA-Based Bionanocomposite Films
tissue loss, as compared to the change in opthalmoscopic finding or the increase
in intraocular pressure [58]. In addition, after the investigation of PVA biocompatibility by food industries, PVA is recommended to be used for the manufacture of
safe biopolymer products [13, 61, 63].
In general, PVA is used after being dissolved in water. Such a polymer can be
dissolved in water when the entire strength of solute-solvent hydrogen bonding
exceeds that of PVA inter-molecular hydrogen bonding [64]. As a result, PVA solubility in water is mainly determined by the degree of hydrolysis. It is noted that
the solubility of PVA with a partial degree of hydrolysis is higher than that of
full-hydrolysis crystalline counterpart [64]. This could be attributed to strong intermolecular hydrogen bonding in case of full hydrolysis when compared with partial
hydrolysis, as shown in Fig. 1.3 [65]. To ensure that PVA has been completely
dissolved in water, the preparation temperature must exceed 80 °C over an acceptable time period [65]. It is believed that the inter- and intrachain hydrogen bonding of
PVA is disrupted by thermal energy. Moreover, the interaction between PVA chains
leads to the increase in solution viscosity, which may further result in phase separation, depending on its degree of hydrolysis, solid content and storage modulus
[66, 67]. On the other hand, partial-hydrolysis PVA can be dissolved in water at
room temperature more readily than full-hydrolysis counterpart [68]. Moreover, the
viscosity of PVA demonstrates a marginal change with the storage time, which is
ascribed to more acetyl groups in PVA with the partial hydrolysis to be responsible
for disrupting inter- and intrachain hydrogen bondings, thus resulting in the increase
of polymeric solubility in water [68].
Fig. 1.3 Intermolecular hydrogen bonding for different types of PVA containing, a full-hydrolysis
molecules and b partial-hydrolysis molecules [65]
1 Introduction to PVA-Based Bionanocomposite Films
tissue loss, as compared to the change in opthalmoscopic finding or the increase
in intraocular pressure [58]. In addition, after the investigation of PVA biocompatibility by food industries, PVA is recommended to be used for the manufacture of
safe biopolymer products [13, 61, 63].
In general, PVA is used after being dissolved in water. Such a polymer can be
dissolved in water when the entire strength of solute-solvent hydrogen bonding
exceeds that of PVA inter-molecular hydrogen bonding [64]. As a result, PVA solubility in water is mainly determined by the degree of hydrolysis. It is noted that
the solubility of PVA with a partial degree of hydrolysis is higher than that of
full-hydrolysis crystalline counterpart [64]. This could be attributed to strong intermolecular hydrogen bonding in case of full hydrolysis when compared with partial
hydrolysis, as shown in Fig. 1.3 [65]. To ensure that PVA has been completely
dissolved in water, the preparation temperature must exceed 80 °C over an acceptable time period [65]. It is believed that the inter- and intrachain hydrogen bonding of
PVA is disrupted by thermal energy. Moreover, the interaction between PVA chains
leads to the increase in solution viscosity, which may further result in phase separation, depending on its degree of hydrolysis, solid content and storage modulus
[66, 67]. On the other hand, partial-hydrolysis PVA can be dissolved in water at
room temperature more readily than full-hydrolysis counterpart [68]. Moreover, the
viscosity of PVA demonstrates a marginal change with the storage time, which is
ascribed to more acetyl groups in PVA with the partial hydrolysis to be responsible
for disrupting inter- and intrachain hydrogen bondings, thus resulting in the increase
of polymeric solubility in water [68].
Fig. 1.3 Intermolecular hydrogen bonding for different types of PVA containing, a full-hydrolysis
molecules and b partial-hydrolysis molecules [65]