Polycondensation, in-situ

In situ polycondensation leads to aromatic polyamides or polyesters dispersed within the matrix of polyarylate. Mechanical and thermal properties of the films formed... 

Two kinds of photoresponsive azobenzene polyurethane functionalized multiwalled carbon nanotube (AzoPU-MWNT) composites were synthesized by in-situ polycondensation (50). Core-shell structures with MWNTs as hard core and polymer layer as soft shell were formed and the average thickness of the grafted polymers was about 7-10 nm. The AzoPU-MWNT composites showed reversible photoisomerism behavior. 

This method, developed by Cadotte and coworkers of Film Tech in the 1970s, is currently most widely used to prepare high-performance reverse osmosis and nanofiltration membranes.A thin selective layer is deposited on top of a porous substrate membrane by interfacial in situ polycondensation. There are a number of modifications of this method primarily based on the choice of the monomers.However, for the sake of simplicity, the polycondensation procedure is described by a pair of diamine and diacid chloride monomers. 

A diamine solution in water and a diacid chloride solution in hexane are prepared. A porous substrate membrane is then dipped into the aqueous solution of diamine. The pores at the top of the porous substrate membrane are filled with the aqueous solution in this process. The membrane is then immersed in the diacid chloride solution in hexane. Because water and hexane are not miscible, an interface is formed at the boundary of the two phases. Poly condensation of diamine and diacid chloride will take place at the interface, resulting in a very thin layer of polyamide. The preparation of composite membranes by the interfacial in situ polycondensation is schematically presented in Fig. 3. 

Song et al. [67] prepared PLA/CNT nanocomposites by one step based on in situ polycondensation of the commercially available lactic acid monomer in the presence of purified CNTs. The TEM image (Fig. 11.5) of core/shell nanostructures clearly indicates that the coating of grafted polymer was uniform both on the CNT s sidewall and tip. It was suggested that the incorporation of CNT into PL A will improvement its solubility and biocompatibility as it may promise a good future in biomedical systems and the development of bio-nanomaterials. The researchers also suggested that the current method of PLA/CNT nanocomposites preparation should be favored in industrialization as it takes less steps and cheaper. 

Baek and co-workers grafted hyperbranched poly(ether ketone)s (HPEKs) on to MWCNTs through an in situ polycondensation of A3 (trimesic acid) and B2 (phenyl ether) monomers in the presence of poly(phosphoric acid) and P2O5. Due to the globular molecular architecture of HPs, the morphology of the nanocomposites resembled mushroom-like clusters on MWCNT stalks . The HPEK-g-MWCNT nanocomposites were soluble in polar aprotic... 

Sforca M, Nunes SP, and Peinemann KV, Composite nanofiltration membranes prepared by in-situ polycondensation of amines in a poly(ethylene oxide-b-amide) layer. Journal of Membrane Science 1997,135,179-186. 

Nodular structures were found not only in the ultrathin and asymmetric membranes but also at the surface of thin film composite (TFC) membranes. Cadotte reported that nodules were closely packed at the surface of a fully aromatic polyamide TFC membrane prepared by the in situ polycondensation reaction between m-phenylene diamine and trimesoyl chloride [3,4]. 

Wei BG, Zhang LY. Chen G (2010) A multi-walled carbon nanotube4>oly(urea-formaldehyde) composite prepared by in situ polycondensation for enhanced electrochemical sensing. New J Chem 34 453-457... 

Nanocomposites of organomodified montmorillonites (C20A, C25A, and C30B) and a biodegradable PEA were obtained by in-situ polycondensation of sodium chloroacetylaminohexanoate [75]. This synthesis was based on a thermal polycondensation reaction in which the formation of a metal halide salt became the driving force of the process [76, 77]. 

For example, SAN is an emulsion or suspension polymerized from styrene plus acrylonitrile, and SAN is graft-polymerized to polybutadiene to form ABS. Antioxidants can be introduced during polymerization as well as during compounding, to protect the double bonds in polybutadiene and acrylonitrile. Block and graft in situ polycondensation polymerization can be used to produce ABS composites and other engineering thermoplastic composites reinforced with poly-p-phenylene terephthal-amide (PPTA) liquid crystal fibers at the molecular level [4]. 

Acrylic acid-grafted polylactide (PLA-g-AA) and multihydroxyl-functionalized multiwalled carbon nanotubes have been melt blended to improve thermal stability and mechanical properties of the composite. The formation of a covalent bond (ester linkage) resulted in a significant improvement in compatibility [98]. Alternatively, carboxylic acid-functionalized multiwalled carbon nanotubes were grafted onto PLEA by a one-step in situ polycondensation reaction [99]. 

The synthesis of polyamides by in situ polycondensation of nylon salts or amino acids in the presence of aryl sulphites and imidazole or pyridine has also been studied and their catalytic activity evaluated. 

Keywords polymer nanocomposite, polyester multiblock elastomer, silica, in situ polycondensation. 

Chen X, Chen X, Lin M, Zhong W, Chen X, Chen Z. Functionalized multi-waUed carbon nanotubes prepared by in situ polycondensation of polyurethane. Macromol Chem Phys 2007 208 964-72. 

Polyamide 6/graphite nanocomposites with markedly low percolation threshold value were recently prepared using an in-situ polycondensation approach. Based on transmission electron microscopy (TEM) results, the thickness of EG filler incorporated in the polymer matrices was found to vary from 10 to 50 nm, and the aspect ratios (diameter to thickness) can be estimated as high as 100-300. The graphite used by Pan et al. is termed foliated graphite (FG). FG can... 

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