Synthesis And Phase Behavior Of Through Intermolecular Hydrogen-bonding

In this dissertation, we have designed and synthesized a series of hydrogenbonded supramolecular side-chain liquid crystalline (LC) polymers (SCLCPs), andinvestigated the self-assembly behavior of the series of supramolecular hydrogenbonded polymer complexes P4VP(nCBP)xwith bent-shaped molecules (nCBP, n=10,12,14) as side chain attaching to Poly(4-vinylpridine)(P4VP) polymer backbone viahydrogen bond interaction between phenol end group of nCBP and pyridine of P4VPin both bulks and thin films. What is more， the hierarchical assemblies ofsupramolecules, which consisted of polystyrene-b-poly(4-vinylpyridine)(PS-b-P4VP)with small molecules (nCBP, n=10,12,14) hydrogen-bonded to the4VP, werealso investigated in both bulks and thin films. The main topics of this paper are asfollows:(1) Three bent-shaped molecules (nCBP, n=10,12,14) were designed andsuccessfully synthesized. The phase behavior of nCBP was characterized by DSC,POM, and SAXS. The results showed that isotropic temperature (Ti) decreases withincreasing alkoxyl tail length, indicating the plasticization of the soft tails. The latticeinformation of LC phase structure of nCBP was obtained via SAXS study. For allnCBPs, three scattering peaks in the low-angle region with a q-ratio of weredetected, indicating the existence of ΦHstructure. As the length of a moleculeassuming all stretched alphatic chains, a head-to-head arrangement with overlap of thealkyl tail is proposed.(2) Supramolecular hydrogen bonded liquid crystalline polymer complexesP4VP(nCBP)xwere prepared and their self-assembly structures in bulk and thin filmswere characterized by means of DSC, POM, and SAXS techniques. Lamellar or ΦHphases were observed in this system depending on the grafting density, aliphatic taillength, and temperature. When increasing x, the phase structure of polymer complexestransform from lamellar to ΦHphase and the threshold value of x dependent phasetransition decreases with increasing the tail length. A nonreversible lamellar to ΦHphase transition appears in the heating process, when P4VP(10CBP)xwith x0.4,P4VP(12CBP)xwith x0.3, and P4VP(14CBP)xwith x0.2. Due to the relativelylarge structure periodicity around6~10nm, the phase morphology could be seen under TEM and AFM. GISAXS revealed that in thin film the phase structurespontaneously oriented parallel to the substrate.(3) The specially designed bent-shaped molecules (nCBP, n=10,12,14) were graftedto the P4VP block of block copolymer PS-b-P4VP to form LC side chains in thesupramolecular complex. Thin films of supramolecular complex were prepared byspin-coating. The phase structures of bulk samples were characterized by means ofDSC, POM, SAXS,2DSAXS and TEM techniques. The P4VP(nCBP)xordering,combined with microphase separation of the BCP, led to the formation of hierarchicalnanostructures. By increasing the nCBP content, BCP phase morphology transformedfrom cylinder, lamellae to inverse cylinder successively. As the hydrogen bondingbetween P4VP and nCBP is temperature sensitive, P4VP(nCBP)xvia its response totemperature and thus change the BCP ordered morphology of the system. The AFMand GISAXS measurements showed that the synergistic coassembly of PS-b-P4VPand nCBP could generate oriented hierarchical structures in thin films. Hierarchicalassemblies, including lamellae-within-lamellae and cylinders-within-lamellae, weresimultaneously ordered and oriented from a few to several tens of nanometers overmacroscopic length scales.