Ph 7.1 7.2 Tris Tromethamine In Polyvinyl Alcohol Buffers Pharmaceutical Intermediates

Tris (hydroxymethyl) aminomethane (Tris) used in polyvinyl alcohol buffers, pharmaceutical intermediates, surfactants

Explanation of the modification of polyvinyl alcohol (PVA) by tris (Tris)

Tris (hydroxymethyl) aminomethane (Tris) can be used to prepare buffers for biochemistry and molecular biology experiments, pharmaceutical intermediates, surfactants and vulcanization accelerators, water-soluble polymers containing Tris structural units, and indoor formaldehyde adsorption Material. The following is an explanation of using Tris to modify polyvinyl alcohol (PVA) to improve its performance.
Polyvinyl alcohol (PVA) is a polymer with a polyhydroxyl structure, which has excellent water solubility, mechanical properties, gas barrier properties and biodegradability. However, the polyhydroxyl structure of PVA easily forms hydrogen bonds between the intramolecular chain and the molecular chain, making the melting point of PVA very close to its decomposition temperature, which makes the thermoforming process very difficult.

At present, the molding of PVA is mainly based on aqueous solution processing, but PVA needs to be dissolved at high temperature, the energy consumption is large, and the molding cycle is long, which greatly limits the application of PVA. Various modification methods are used at home and abroad to realize the thermoplastic processing of PVA, such as the use of glycerol and the hydroxyl groups on the PVA molecular chain to weaken the hydrogen bond of PVA and lower the melting point of PVA, but glycerol is easy to precipitate from the PVA matrix, which affects the performance of the material. . Chemical modification is to use the high reactivity of the PVA hydroxyl group to introduce thermally stable functional groups into the PVA molecular chain, destroy the regularity of the PVA molecular chain, weaken the hydrogen bond between the PVA molecular chain, and finally realize the thermoplastic processing of the PVA. It is difficult to maintain the inherent performance of PVA itself.
Researchers carboxylated polyvinyl alcohol (PVA) hydroxyl groups, and then reacted with Tris in an amide reaction to prepare Tris-modified polyvinyl alcohol (PVA-COOTRIS). Tris is a kind of polyhydroxy compound. The polyhydroxy structure is introduced into the PVA side chain, which can reduce the damage to the PVA hydrogen bond by modification, thereby changing the regular structure of the PVA molecular chain, reducing the crystallinity and melting point of the PVA, and improving its thermal stability It can broaden the thermal processing window of PVA and realize the thermoplastic processing of PVA.

The specific operations are as follows:
(1) Dissolve 4.40g polyvinyl alcohol in 200ml dry dimethyl sulfoxide and pour it into a 500ml round bottom flask;
(2) Add 0.5 g of succinic anhydride (5 Mmol) and triethylamine catalyst (TEA) to the above solution;
(3) After stirring the reaction at room temperature for 24 hours, add 0.96g (5 Mmol) 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) and 0.56g (5 Mmol) ) N-hydroxysuccinimide (NHS);
(4) Stir for another 0.5 h, add 0.60 g (5 Mmol) Tris, and continue the reaction for 24 h.
Researchers used infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical thermal analysis and mechanical performance testing to study the influence of the introduction of TRIS on the structure and performance of PVA. Finally, it was found that the introduction of Tris (CAS 77-86-1) changed the molecular structure of PVA, the introduced functional groups interacted with the hydroxyl groups in PVA, increased the decomposition temperature, obtained a wider melt processing window, and realized the PVA Thermoplastic processing, no need to add any plasticizer. The mechanical properties of PVA modified by Tris are improved, the tensile strength is reduced, and the elongation at break is increased.