A series of main-chain benzoxazine oligomers with different methyl substitutions are successfully synthesized. Chemical structures are analyzed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Effects of methyl substitutions on chemical shifts of protons in oxazine ring and thermal properties, including glass transition temperature, thermal stability, and char yield, are discussed. The influences of methyl substitutions on different positions are demonstrated: (i) substitution on phenols induces obvious increase in curing temperature while substitution on amine does not show apparent impact; (ii) substitution at different positions results in Tg variation, following the sequence of none-substitution > substitution at end-capping > substitution on diamines in main-chain > substitution on bisphenols in main-chain; and (iii) substitution at end-capping would cause apparent deterioration in thermal stability while substitution on diamines in main-chain would benefit thermal stability and char yield. Experimental results and related explanations are provided in detail.
IshidaH.Overview and historical background of polybenzoxazine research. In: IshidaHAgagT (eds) Handbook of benzoxazine resins. Amsterdam: Elsevier, 2011, pp. 3–81.
2.
OhashiSIshidaH.Various synthetic methods of benzoxazine monomers. In: IshidaHFroimowiczP (eds) Advanced and emerging polybenzoxazine science and technology. Amsterdam: Elsevier, 2017, pp. 3–8.
3.
RimdusitSIshidaH. Development of new class of electronic packaging materials based on ternary systems of benzoxazine, epoxy, and phenolic resins. Polymer2000; 41: 7941–7949.
4.
LinCHHuangSJWangPJ, et al.Miscibility, microstructure, and thermal and dielectric properties of reactive blends of dicyanate ester and diamine-based benzoxazine. Macromolecules2012; 45: 7461–7466.
ZhangKYuX. Catalyst-free and low-temperature terpolymerization in a single-component benzoxazine resin containing both norbornene and acetylene Functionalities. Macromolecules2018; 51: 6524–6533.
7.
WangYWuGKouK, et al.Mechanical, thermal conductive and dielectrical properties of organic montmorillonite reinforced benzoxazine/cyanate ester copolymer for electronic packaging. J Mater Sci: Mater Electron2016; 27: 8279–8287.
8.
ZhangLMaoJWangS, et al.Benzoxazine based high performance materials with low dielectric constant: a review. Curr Org Chem2019; 23: 809–822.
WangXZongLHanJ, et al.Toughening and reinforcing of benzoxazine resins using a new hyperbranched polyether epoxy as a non-phase-separation modifier. Polymer2017; 121: 217–227.
11.
ZhaoPZhouQDengYY, et al.Reaction induced phase separation in thermosetting/thermosetting blends: effects of imidazole content on the phase separation of benzoxazine/epoxy blends. RSC Adv2014; 4: 61634–61642.
12.
WangZRanQZhuR, et al.A novel benzoxazine/bismaleimide blend resulting in bi-continuous phase separated morphology. RSC Adv2013; 3: 1350–1353.
13.
GowardGRSebastianiDSchnellI, et al.Benzoxazine oligomers: evidence for a helical structure from solid-state NMR spectroscopy and DFT-based dynamics and chemical shift calculations. J Am Chem Soc. 2003; 125: 5792–5800.
14.
KuoSWWuYCWangCF, et al.Preparing low-surface-energy polymer materials by minimizing intermolecular hydrogen-bonding interactions. J Phys Chem C2009; 113: 20666–20673.
15.
YangPWangXFanH, et al.Effect of hydrogen bonds on the modulus of bulk polybenzoxazines in the glassy state. Phys Chem Chem Phys2013; 15: 15333–15338.
16.
BaiYYangPSongY, et al.Effect of hydrogen bonds on the polymerization of benzoxazines: influence and control. RSC Adv2016; 6: 45630–45635.
17.
TakeichiTKanoTAgagT. Synthesis and thermal cure of high molecular weight polybenzoxazine precursors and the properties of the thermosets. Polymer2005; 46: 12172–12180.
18.
TüzünALligadasGRondaJC, et al.Integrating plant oils into thermally curable main-chain benzoxazine polymers via ADMET polymerization. Eur Polym J2015; 67: 503–512.
LinCHChangSLShenTY, et al.Flexible polybenzoxazine thermosets with high glass transition temperatures and low surface free energies. Polym Chem. 2012; 3: 935–945.
21.
DemirKDKiskanBAydoganB, et al.Thermally curable main-chain benzoxazine prepolymers via polycondensation route. React Func Polym2013; 73: 346–359.
22.
ShiJZhengXXieL, et al.Film-forming characteristics and thermal stability of low viscosity benzoxazines derived from melamine. Eur Polym J2013; 49: 4054–4061.
23.
FengTWangJWangH, et al.Copolymerization of fluorene-based main-chain benzoxazine and their high performance thermosets. Polym Adv Tech2015; 26: 581–588.
24.
LiuNLiLWangL, et al.Organic-inorganic polybenzoxazine copolymers with double decker silsesquioxanes in the main chains: synthesis and thermally activated ring-opening polymerization behavior. Polymer2017; 109: 254–265.
25.
LiaoYTLinYCKuoSW. Highly thermally stable, transparent, and flexible polybenzoxazine nanocomposites by combination of double-decker-shaped polyhedral silsesquioxanes and polydimethylsiloxane. Macromolecules2017; 50: 5739–5747.
26.
LiuJAgagTIshidaH.Main-chain benzoxazine oligomers: a new approach for resin transfer moldable neat benzoxazines for high performance applications. Polymer2010; 51: 5688–5694.
27.
LiuJScottCWinrothS, et al.Copolymers based on telechelic benzoxazine with a reactive main-chain and anhydride: monomer and polymer synthesis, and thermal and mechanical properties of carbon fiber composites. RSC Adv2015; 5: 16785–16791.
28.
ZhangKQiuJLiS, et al.Remarkable improvement of thermal stability of main-chain benzoxazine oligomer by incorporating ortho-norbornene as terminal functionality. J Appl Polym Sci2017; 134: 45408.
29.
ZhengJGuoHGanJ, et al.Synthesis and characterization of novel bisphthalonitrile resins linked by different molecular weight main-chain polybenzoxazines. J Macromol Sci Part A: Pure Appl Chem2016; 53: 180–187.
30.
ŠtirnŽRučigajAKrajncM. Innovative approach using aminomaleimide for unlocking phenolic diversity in high-performance maleimidobenzoxazine resins. Polymer2017; 120: 129–140.
31.
ZhangLMaoJWangS, et al.Meta-phenylenediamine formaldehyde oligomer: a new accelerator for benzoxazine resin. React Func Polym2017; 121: 51–57.
32.
ZhangLYangYChenY, et al.Cardanol-capped main-chain benzoxazine oligomers for resin transfer molding. Eur Polym J2017; 93: 284–293.
33.
ZengMChenJXuQ, et al.A facile method for the preparation of aliphatic main-chain benzoxazine copolymers with high-frequency low dielectric constants. Polym Chem2018; 9: 2913–2925.
34.
DaiJTengNShenX, et al.Synthesis of biobased benzoxazines suitable for vacuum-assisted resin transfer molding process via introduction of soft silicon segment. Ind Eng Chem Res2018; 57: 3091–3102.
35.
RučigajAŠtirnZŠebenikU, et al.Main-chain benzoxazine oligomers: effects of molecular weight on the thermal, mechanical and viscoelastic properties. J Appl Polym Sci2081; 135: 46659.
36.
WangJWuMLiuW, et al.Synthesis, curing behavior and thermal properties of fluorene containing benzoxazines. Eur Polym J2010; 46: 1024–1031.
37.
WangHWangJHeX, et al.Synthesis of novel furan-containing tetrafunctional fluorene-based benzoxazine monomer and its high performance thermoset. RSC Adv2014; 4: 64798–64801.
38.
WangJRenTWangY, et al.Synthesis, curing behavior and thermal properties of fluorene-containing benzoxazines based on linear and branched butylamines. React Func Polym2014; 74: 22–30.
39.
ChenYHeXDayoAQ, et al.Synthesis and characterization of cardanol containing tetra-functional fluorene-based benzoxazine resin having two different oxazine ring structures. Polymer2019; 179: 121620.
40.
AllenDJIshidaH. Effect of phenol substitution on the network structure and properties of linear aliphatic diamine-based benzoxazines. Polymer2009; 50: 613–626.
41.
OieHMoriASudoA, et al.Synthesis of networked polymer based on ring-opening addition reaction of 1,3-benzoxazine with resorcinol. J Polym Sci A: Polym Chem2012; 50: 4756–4761.
42.
SiniNKBijweJVarmaIK. Renewable benzoxazine monomer from Vanillin: synthesis, characterization, and studies on curing behavior. J Polym Sci A: Polym Chem2014; 52: 7–11.
43.
IshidaHSandersDP. Regioselectivity and network structure of difunctional alkyl-substituted aromatic amine-based polybenzoxazines. Macromolecules2000; 33: 8149–8157.
44.
IshidaHSandersDP. Regioselectivity of the ring-opening polymerization of monofunctional alkyl-substituted aromatic amine-based benzoxazines. Polymer2001; 42: 3115–3125.
45.
WangJHeXYLiuJT, et al.Investigation of the polymerization behavior and regioselectivity of fluorene diamine based benzoxazines. Macromol Chem Phys2013; 214: 617–628.
46.
ZhangLZhengYFuR, et al.Contribution of blocking positions on the curing behaviors, networks and thermal properties of aromatic diamine-based benzoxazines. Thermochim Acta2018; 668: 65–72.
47.
WangMWJengRJLinCH. Study on the ring-opening polymerization of benzoxazine through multisubstituted polybenzoxazine precursors. Macromolecules2015; 48: 530–535.
48.
HanLIguchiDGilP, et al.Oxazine ring-related vibrational modes of benzoxazine monomers using fully aromatically substituted, deuterated, 15 N isotope exchanged, and oxazine-ring-substituted compounds and theoretical calculations. J Phys Chem A2017; 121: 6269–6282.
49.
HanLSalumMLZhangK, et al.Intrinsic self-initiating thermal ring-opening polymerization of 1,3-benzoxazines without the influence of impurities using very high purity crystals. J Polym Sci Part A: Polym Chem2017; 55: 3434–3445.
50.
AndreuRReinaJARondaJC. Studies on the thermal polymerization of substituted benzoxazine monomers: electronic effects. J Polym Sci Part A: Polym Chem2008; 46: 3353–3366.
51.
MartosASebastiánRMMarquetJ.Studies on the ring-opening polymerization of benzoxazines: understanding the effect of the substituents. Eur Polym J2018; 108: 20–27.
52.
FroimowiczPZhangKIshidaH.Intramolecular hydrogen bonding in benzoxazines: when structural design becomes functional. Chem Eur J2016; 22: 2691–2707.
53.
HemvichianKLaobutheeAChirachanchaiS, et al.Thermal decomposition processes in aromatic amine-based polybenzoxazines investigated by TGA and GC-MS. Polymer2002; 43: 4391–4402.
