Study On The Structure And Capability Of The Thermally Crosslinkable Multi-block Copolymers Synthesized Via Mannich Polycondensation

An important strategy for making polymer materials with combined properties is to prepare block copolymers consisting of well-defined blocks via facile approaches.In this thesis, Poly(hydroxyether of bisphenol A)-block-polydimethylsiloxane alternating block copolymers (PH-alt-PDMS) were synthesized via Mannich polycondensation involving phenolic hydroxyl-terminated poly(hydroxyether of bisphenol A), diaminopropyl-terminated polydimethylsiloxane and formaldehyde. The polymerization was carried out via the formation of benzoxazine ring linkages between poly(hydroxyether of bisphenol A) and polydimethylsiloxane blocks. Differential scanning calorimetry and small-angle X-ray scattering show that the alternating block copolymers are microphase-separated. Compared to poly(hydroxyether of bisphenol A), the copolymers displayed enhanced surface hydrophobicity (dewettability). In addition, subsequent crosslinking can occur upon heating the copolymers to elevated temperatures owing to the existence of benzoxazine linkages in the microdomains of hard segments. The subsequent self-crosslinking of the PH-alt-PDMS alternating block copolymers could lead to these polymer materials having potential applications.Poly(benzoxazine of 4,4'diaminodiphenylmethane) -b- polydimethylsiloxane multi-block copolymers (PBDDM-b-PDMS) were synthesized via the Mannich polycondensation between the phenolic hydroxyls-terminated poly(h benzoxazine of diaminodiphenylmethane) with variable molecular weights and diamino-terminated polydimethylsiloxane (ATPDMS) by one pot. The micro-separated morphology of the alternating block copolymers was proved by Atomic Force Microscopy and Small Angle X-ray scattering, and the nanodomains of PDMS were dispersed in the crosslinked polybenzoxazine matrix. Non-isothermal differential scanning calorimetry (DSC) at different heating rates is used to determine the kinetic parameters of the curing processes of the PBDDM-b-PDMS. Compared to the control polybenzoxazine, the PBDDM-b-PDMS had higher activation energy and less enthalpy of the curing reaction. Thermogravimetric analysis (TGA) was applied to evaluate the thermal stability and the surface properties of the copolymer were investigated in terms of the measurement of static contact angle.