Lipase-Catalyzed Synthesis and Properties of Silicone Aromatic Polyesters and Silicone Aromatic Polyamides

Abstract

Candida antarctica lipase B (CALB) immobilized on a macroporous acrylic resin (Novozym 435) was used to enzymatically synthesize silicone aromatic polyesters (SAPEs) and silicone aromatic polyamides (SAPAs) in toluene under mild reaction conditions. The SAPEs were synthesized using R,ω-(dihydroxyalkyl)-terminated poly(dimethylsiloxane) (HAT-PDMS, molar mass M n = 2500 g mol -1 ), and the SAPAs were synthesized using R,ω-(diaminopropyl)-terminated poly(dimethylsiloxane) (APT-PDMS, having two different molar masses, M n , 1000 and 4700 g mol -1 , respectively). Each of the polymers was made by a transesterification reaction with dimethyl terephthalate (DMT) in toluene (1:2 w/v ratio of monomers to solvent) at a temperature in the range of 80-90 °C under vacuum. Toluene was employed as the solvent in order to solubilize the DMT in the reaction mixture. The methanol byproduct was recovered from the reaction mixture along with the toluene by applying vacuum, and thus the transesterification reaction was driven forward. The enzymatically synthesized polymers were characterized by GPC, FTIR, 1 H NMR, XRD, DSC, and TGA. Higher molar masses were obtained for the SAPEs compared to those of the SAPAs, even though similar reaction conditions were used. The thermal properties of the resulting polymers were seen to depend on the molar masses of the SAPEs and the SAPAs. Both types of polymer were found to be amorphous liquids at room temperature. However, below room temperature the SAPA samples were found to be a sticky wax-like material which contained a crystal-like phase that showed a melting endotherm by DSC analysis. The absence of a melting endotherm in the SAPEs and the relatively low melting point of the SAPAs may be attributed to the presence of long chain highly flexible PDMS segments in the polymers.

On the Role of Tin Catalysts in Step-Growth Polymerization Reactions

“…11). In particular we are investigating molecules, macromolecules, biomolecules, biomacromolecules and various enzymes as catalysts and biocatalysts for siloxanebased systems [34][35][36][37][38][39][40][41].…”

Biocatalysis in Silicon Chemistry

“…[86][87][88] Since our last review of the field of biocatalysis in silicon chemistry in 2009, [17] Clarson and Poojaric arriedo ut the CalB-mediated polymerization of 1,3-bis(3-carboxypropyl)-1,1,3,3-tetramethyldisiloxane and polyethylene glycol (PEG) 400, 1000, and 3400, as well as between a,w-hydroxyalkyl-terminated silicone and diacid-functionalized PEG chains, [89] and showedt he synthesis of silicone polyesters and polyamides. [90] Polymerization of the tetramethyldisiloxane (TMDS)d iacid and the PEG chains afforded high-molecular-weight polymers. However, increasing the chain length of the PEG chain resulted in as harp decrease in the average degree of polymerization, which was attributedt op hase separation between the hydrophobic disiloxane and hydrophilic PEG chains.…”

“…[91] In 2010, Poojari and Clarson synthesized silicone aromatic polyesters and polyamides in toluene and under reduced pressure. [90] By using dimethyl terephthalate ande ither a,w-hydroxypropyl-or a,w-aminopropyl-terminated silicones, aromatic polyesters and polyamides were produced, giving aw eightaverage molecular mass of 52 000 gmol À1 for polyesters and 60 000 gmol À1 for polyamides.I ne ither case, the dispersity of the weight-average molecular weights decreased over the course of the 96 hr eaction to reacha sl ow as 1.37 and 1.50, respectively.…”

Modification of Thermoplastics with Reactive Silanes and Siloxanes

“…Lipase-catalyzed synthesis of aromatic silicone polyesters (SAPEs) and polyamides (SAPAs) have been reported (Poojari & Clarson, 2010). The SAPEs were synthesized using α,ω-dihydroxyalkyl-terminated PDMS, and the SAPAs were prepared with α,ω-diaminoalkyl-terminated PDMS via transesterification reaction with dimethyl terephthalate in toluene at a temperature in the range 80-90 C.…”