Hydroxypropylation of Polyphenol-Rich Alkaline Extracts from <i>Pinus radiata</i> Bark and Their Physicochemical Properties
<i>Pinus radiata</i> bark is a rich source of polyphenols, which are mainly composed of proanthocyanidins. This study aimed to utilize <i>P. radiata</i> bark as a polyol source for bio-foam production in the future. Polyphenol-rich alkaline extracts (AEs) from <i>P. rad...
| Main Author: | |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2022-12-01
|
| Series: | Molecules |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1420-3049/27/24/9002 |
| _version_ | 1797455996376842240 |
|---|---|
| author | Sung Phil Mun |
| author_facet | Sung Phil Mun |
| author_sort | Sung Phil Mun |
| collection | DOAJ |
| description | <i>Pinus radiata</i> bark is a rich source of polyphenols, which are mainly composed of proanthocyanidins. This study aimed to utilize <i>P. radiata</i> bark as a polyol source for bio-foam production in the future. Polyphenol-rich alkaline extracts (AEs) from <i>P. radiata</i> bark were prepared by mild alkaline treatment and then derivatized with propylene oxide (PO). Hydroxypropylated alkaline extracts (HAEs) with varying molar substitutions (MS 0.4–8.0) were characterized by FT-IR, NMR, GPC, TGA, and DSC. The hydroxyl value and solubility in commercial polyols were also determined. The molecular weights of the acetylated HAEs (Ac-HAEs) were found to be 4000 to 4900 Da. Analyses of FT-IR of HAEs and <sup>1</sup>H NMR of Ac-HAEs indicated that the aromatic hydroxyl groups were hydroxypropylated and showed an increase in aliphatic hydroxyl group content. The glass transition temperature (T<sub>g</sub>) of AE and HAEs were 58 to 60 °C, showing little difference. The hydroxyl value increased as the hydroxypropylation proceeded. Although salts were produced upon neutralization after hydroxypropylation, HAEs still showed suitable solubility in polyether and polyester polyols; HAEs dissolved well in polyether polyol, PEG#400, and solubility reached about 50% (<i>w</i>/<i>w</i>). This indicated that neutralized HAEs could be directly applied to bio-foam production even without removing salts. |
| first_indexed | 2024-03-09T16:02:08Z |
| format | Article |
| id | doaj.art-4da25c108e924e949d31167c7684cfbd |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-09T16:02:08Z |
| publishDate | 2022-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-4da25c108e924e949d31167c7684cfbd2023-11-24T17:01:07ZengMDPI AGMolecules1420-30492022-12-012724900210.3390/molecules27249002Hydroxypropylation of Polyphenol-Rich Alkaline Extracts from <i>Pinus radiata</i> Bark and Their Physicochemical PropertiesSung Phil Mun0Department of Wood Science and Technology, Jeonbuk National University, Jeonju 54896, Republic of Korea<i>Pinus radiata</i> bark is a rich source of polyphenols, which are mainly composed of proanthocyanidins. This study aimed to utilize <i>P. radiata</i> bark as a polyol source for bio-foam production in the future. Polyphenol-rich alkaline extracts (AEs) from <i>P. radiata</i> bark were prepared by mild alkaline treatment and then derivatized with propylene oxide (PO). Hydroxypropylated alkaline extracts (HAEs) with varying molar substitutions (MS 0.4–8.0) were characterized by FT-IR, NMR, GPC, TGA, and DSC. The hydroxyl value and solubility in commercial polyols were also determined. The molecular weights of the acetylated HAEs (Ac-HAEs) were found to be 4000 to 4900 Da. Analyses of FT-IR of HAEs and <sup>1</sup>H NMR of Ac-HAEs indicated that the aromatic hydroxyl groups were hydroxypropylated and showed an increase in aliphatic hydroxyl group content. The glass transition temperature (T<sub>g</sub>) of AE and HAEs were 58 to 60 °C, showing little difference. The hydroxyl value increased as the hydroxypropylation proceeded. Although salts were produced upon neutralization after hydroxypropylation, HAEs still showed suitable solubility in polyether and polyester polyols; HAEs dissolved well in polyether polyol, PEG#400, and solubility reached about 50% (<i>w</i>/<i>w</i>). This indicated that neutralized HAEs could be directly applied to bio-foam production even without removing salts.https://www.mdpi.com/1420-3049/27/24/9002<i>Pinus radiata</i> barkalkaline extractpropylene oxide (PO)hydroxypropylationmolar substitution (MS)PEG#400 |
| spellingShingle | Sung Phil Mun Hydroxypropylation of Polyphenol-Rich Alkaline Extracts from <i>Pinus radiata</i> Bark and Their Physicochemical Properties Molecules <i>Pinus radiata</i> bark alkaline extract propylene oxide (PO) hydroxypropylation molar substitution (MS) PEG#400 |
| title | Hydroxypropylation of Polyphenol-Rich Alkaline Extracts from <i>Pinus radiata</i> Bark and Their Physicochemical Properties |
| title_full | Hydroxypropylation of Polyphenol-Rich Alkaline Extracts from <i>Pinus radiata</i> Bark and Their Physicochemical Properties |
| title_fullStr | Hydroxypropylation of Polyphenol-Rich Alkaline Extracts from <i>Pinus radiata</i> Bark and Their Physicochemical Properties |
| title_full_unstemmed | Hydroxypropylation of Polyphenol-Rich Alkaline Extracts from <i>Pinus radiata</i> Bark and Their Physicochemical Properties |
| title_short | Hydroxypropylation of Polyphenol-Rich Alkaline Extracts from <i>Pinus radiata</i> Bark and Their Physicochemical Properties |
| title_sort | hydroxypropylation of polyphenol rich alkaline extracts from i pinus radiata i bark and their physicochemical properties |
| topic | <i>Pinus radiata</i> bark alkaline extract propylene oxide (PO) hydroxypropylation molar substitution (MS) PEG#400 |
| url | https://www.mdpi.com/1420-3049/27/24/9002 |
| work_keys_str_mv | AT sungphilmun hydroxypropylationofpolyphenolrichalkalineextractsfromipinusradiataibarkandtheirphysicochemicalproperties |