Direct synthesis of functional novolacs and their polymer reactions

Abstract

We report the direct synthesis of new functional novolacs having allyl ether (4) or bromoalkyl groups (5 and 6) in the side chain by the addition-condensation of allyl phenyl ether (1), 1-bromo-2-phenoxyethane (2) or 1-bromo-4-phenoxybutane (3) with formaldehyde. The structure of these novolacs was confirmed by Fourier transform infrared, 1 H NMR and 13 C NMR spectra. The number-average molecular weights (M n ) of the obtained polymers were found to be B1000-3000. In the case of the polymerization of 1 with formaldehyde using hydrated sulfuric acid as a catalyst, Claisen condensation did not occur with the polymerization; therefore, pure allylated novolac (4) without a phenol moiety was obtained. Thus, in this process, phenolformaldehyde condensation proceeded under such conditions that the functional group was not affected. These polymers (4-6) have considerable potential as reactive polymers in the field of materials science. Their applications are as follows: (i) a key reaction of a latent curing system: thermal stimuli-induced Claisen rearrangement of allylated novolac to generate phenolic hydroxyl groups; (ii) vinyl ether-modified novolac (7) prepared by 1-bromoethoxy-group-modified novolac; and (iii) an amphiphilic graft-shaped polymer prepared by bromoalkyl-group-modified novolac-initiated ring-opening polymerization of 2-methyl-2-oxazoline. Polymer Journal ( Keywords: allyl phenyl ether; Claisen condensation; graft polymerization; novolac; phenolic resin; polycondensation; polymer reaction INTRODUCTION Phenolic resins 1-10 and related polymers 11-22 are a very important class of common organic polymers, and have numerous applications in the development of materials 1-6 such as thermosetting resins, adhesives, photoresists and polymer composites. The main characteristics of phenolic resins, such as heat stability and mechanical properties, are attributed to their rigid rod-like polymer backbone of poly(phenylenemethylene). 2,23 From this viewpoint, we have synthesized a wide variety of aromatic polymers from alkoxylated phenol derivatives such as anisole, phenethol and diphenyl ether by a method similar to acid-catalyzed phenol-formaldehyde condensation. 2,[23][24][25][26][27][28][29][30][31][32][33] The obtained polymers exhibit good solubility in organic solvents and they are more resistant to heat and oxidation than are phenolic novolacs. Furthermore, using hydroxyl-group-functionalized phenol derivatives, a functional novolac can be prepared by a one-step procedure. Therefore, a desired polymer can be designed using this methodology (Figure 1). It is very important to extend the use of this methodology to a wide variety of applications in the field of materials science.Reactive polymers have attracted considerable interest in the field of materials science because their characteristics and functions can be enhanced to develop crosslinking agents, resist materials, expandable

Propargylated novolac resins for fibre‐reinforced plastics: Processing aspects

“…To overcome these difficulties, chemical modification of the resin with an addition polymerization curing mechanism is commonly performed . It is known that introduction of allyl, propargyl, maleimide, phenylethinyl, etc. increases heat and thermooxidation resistance and changes the curing process to be of addition type.…”

Synthesis of a branched poly(phenylene ethylene) with bromomethyl groups as an organosoluble and functional parylene

“…In contrast, 6 was obtained in high yield and had a high molecular weight. This was because 6 is more organosoluble than 4 and 5 , because of the high flexibility of the methoxy groups 16–25. Alkoxy groups can add good solubility to aromatic polymer such as poly(phenylenemethylene) 26, 27.…”

Carbon molecular sieve membranes for selective CO2 separation at elevated temperatures and pressures

“…CMSMs are synthesized by carbonization of a thermosetting polymer under non-oxidant atmospheres, and depending on the synthesis procedure and the selected precursors, different micro-structures can be tailored in carbon membrane layer [18], which along with their high thermal and chemical stability [19] provide the desired characteristics for wide range of gas separation applications [20]. Facilitating the CO 2 adsorption on the tailored CMSM with co-polymerization of Novalac oligomer [20][21][22] with ethylenediamine has been proven to be an efficient method due to increasing the functional groups on the CMSMs microporous structure. However, these membranes have not yet been optimized for high temperatures and pressures applications.…”