The molecules containing the hydroxyl groups bonded are called alcohols with the general formula CnH2n+1OH. Once the hydroxyl groups are installed on the aromatic rings, they got a new name, “phenols”. The OH group can privilege many unique properties for the molecules, such as hydrophilia, which are responsible for their broad applications in energy sources, detergents and plasticizers. (Fig.1) The alcohols can be classified as primary, secondary and tertiary alcohols based on the carbon substituted situation. The alcohols always play an important roles in our human history especially ethanol which wildly dispersed in alcoholic beverage.
Fig.1 Classification of alcohols and derivatives
There are different classifications of alcohols. According to the different types of hydroxyl connected carbon, it can be divided into primary alcohol, secondary alcohol and tertiary alcohol; according to the different types of connected hydroxyl, it can be divided into fatty alcohol, ester cycloalcohol and aromatic alcohol. According to the hydrocarbon group, fatty alcohol can be divided into saturated alcohol and unsaturated alcohol; according to the different hydroxyl contained in the molecule, it can be divided into monohydric alcohol, binary alcohol, ternary alcohol, etc. Polyols are composed of two or more hydroxyl groups.
Polyvinyl alcohol is one of the most versatile and biocompatible, since by chemical or physical modification its properties are modulated, improving drug stability, drug targeting, and ensures patient compliance. Since its discovery, this material has been used for many applications. For instance, in the production of composites reinforced with polyester or cellulose to give mechanical strength to carbon nanotubes. Freezing-thawing cycles, heat treatment and formation of composites are the most significant physical modifications to improve the performance of polyvinyl alcohol. On the other hand, the chemical modifications by cross-linking with aldehydes, carboxylic acids, sodium tetraborate, epichlorohydrin have enhanced the physical and mechanical properties, such as the oil sorption ability, oxygen and waterproof characteristics, mechanical strength, drug diffusion and rate of swelling.
Amino alcohols have been used extensively in asymmetric synthesis, both as chiral ligands and auxiliaries (Fig.2). The two heteroatoms allow great flexibility, as one or both can be bound to a Lewis acid, transition metal, or achiral starting material. Syntheses of and the role of 1,2-aminoalcohols and their derivatives as chiral auxiliaries have been wildly reported. While less abundant than the 1,2-aminoalcohols, 1,3-aminoalcohols have also contributed significantly to the advancement of asymmetric synthesis. Many have found use as chiral ligands or auxiliaries, and there have also been applications as a resolving agent and as a phase transfer catalyst.
Fig.2 The selected examples of alcohols for asymmetric organic catalysis (cited from Chem. Rev.)
Stimuli-responsive polymers can undergo changes in chain conformation, solubility, and self-assembly along with the stimuli from environment. There are common strategies to incorporate stimuli-responsive functions onto PVA (polyvinyl alcohol polymer) to achieve certain performance requirements (Fig.3). For instance, with the aim of improving the reversibility of PVA adhesive, a typical thermally responsive polymer, poly(N-isopropylacrylamide) (PNIPAM), was grafted onto PVA glue, and the obtained PVA-g-PNIPAM exhibited temperature-dependent reversible adhesion. By taking advantage of the thermal expansion and abundant hydroxyl groups, PVA has been added into some thermosensitive nanocarriers to improve drug leakage and thermal stability.
Fig.3 Presentation for the Preparation of DEEDA Modified PVA (cited from Macromolecules)
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