Fluorescence spectra of ladderlike polyphenylsilsesquioxane (LPPS) and ladderlike 1,4-phenylene-bridged polyvinylsiloxane (LPPVS) have been measured as a function of temperature (4-55 degreesC), in dilute tetrahydrofu...Fluorescence spectra of ladderlike polyphenylsilsesquioxane (LPPS) and ladderlike 1,4-phenylene-bridged polyvinylsiloxane (LPPVS) have been measured as a function of temperature (4-55 degreesC), in dilute tetrahydrofuran solution. The excimer (IF) to monomer (I-M) intensity ratio (I-E/I-M) of LPPS dilute solution shows a double linear Arrhenius plot with a break point ascribable to a transition temperature Tt. This behavior has not been found for single chain polyorganosiloxanes. When In/(E) of LPPS was plotted against 1/T, it also gave a double linear plot with one break point, which was found in single chain polyorganosiloxanes. The different behaviors between LPPS and single chain polyorganosiloxanes may be mainly attributed to the relatively rigid double-chain macromolecular backbone of LPPS. However, the 1n(I-E/I-M) of dilute LPPVS solution versus 1/T shows a simple linear variation with a positive slope which confirms our proposition. The difference between the fluorescence results of LPPS and those of LPPVS may possibly derive from their structure differences and cooperative motion in backbone chain bonds.展开更多
A novel ordered reactive oligomeric ladderlike copolymethyl-aminopropylsilsesquioxane(Me-AP-T),was successfully synthesized by an efficient hydrosilylation graft reaction of 1,1,1-trimethyl-N-2-propenyl-silanamine wit...A novel ordered reactive oligomeric ladderlike copolymethyl-aminopropylsilsesquioxane(Me-AP-T),was successfully synthesized by an efficient hydrosilylation graft reaction of 1,1,1-trimethyl-N-2-propenyl-silanamine with a reactive oligomeric ladderlike copolymethyl-hydrosilsesquioxane(Me-H-T),which was prepared by“supramolecular chemistry-dictated stepwise coupling polymerization”process.FT-IR,~1H-and ^(29)Si-NMR spectra show that hydrosilylation reaction proceeds completely.Moreover,~1H-NMR spectra also indicate that both the molar ratios of≡SiMe group to Si—H and≡SiMe group to≡SiPrNH_2 are approximately 1:1 respectively based on the ratio of integrated resonance areas of the different groups.XRD analysis and ^(29)Si-NMR spectra are used for investigating the ladderlike structure of the polymers.A high T_g(128.38℃)of Me-AP-T shown in DSC measurement implies that the ordered reactive Me-AP-T macromolecules have much stiff chains.展开更多
The high molecular ladderlike polyhydrosilsesquioxane （LPHSQ） and its copolymer, ladderlike random copolymethylhydrosilsesquioxane （LR-PMHSQ） and ladderlike block copolymethylsilsesqui-oxane（LB-PMHSQ） have been ...The high molecular ladderlike polyhydrosilsesquioxane （LPHSQ） and its copolymer, ladderlike random copolymethylhydrosilsesquioxane （LR-PMHSQ） and ladderlike block copolymethylsilsesqui-oxane（LB-PMHSQ） have been synthesized by a preaminolysis reaction of the corresponding trichlorosilane with 1 ,4-phenylene diamine（PDA） then by hydrolysis and polycondensation reactions The thermographs of these polymers measured by DSC method indicate that these macromolecular backbones are very rigid as seen from the DSC curves which are almost horizontal from room temperature until 350;without noticeable glass transition. The content of Si—H group in the polymers can be regulated by changing the composition of the two copolymerized monomers. So the ladderlike polymers including its copolymers can be the useful precursors for the functional polymers, especially such as fishbone-like liquid crystalline polymers.展开更多
Blends of PC and PPSQ (A) with high M-w and good ladderlike regularity or PPSQ(B) with low M-w and more defective Si-atoms in its structure have been prepared by solution casting. The dispersed spheres (PPSQ(A)-rich) ...Blends of PC and PPSQ (A) with high M-w and good ladderlike regularity or PPSQ(B) with low M-w and more defective Si-atoms in its structure have been prepared by solution casting. The dispersed spheres (PPSQ(A)-rich) are unevenly dispersed in the continuous PC-rich phase and there is no phase-inversion as PPSQ(A) content increases when the percentage of PPSQ(A) is not more than 70%. PPSQ(B)-rich spheres are evenly dispersed in the continuous phase (PC-rich) and phase-inversion occurs when PPSQ(B) percentage is up to 70%. T-g of PPSQ(A)/PC or PPSQ(B)/PC at some compositions are lower than that of pure PC due to the enlarged free-volume of PC-rich phase because some spheres of rigid PPSQ chains are included in the PC-rich phase. PC and PPSQ(A) or PPSQ(B) are partially compatible. The compatibility of PC and PPSQ(B) is better than that of PC and PPSQ(A) with high M-w and good ladderlike regularity. Heat history has some influence on the T(g)s and compatibility of PPSQ(A)/PC and PPSQ(B)/PC blends.展开更多
Heat-resistant silicone gels were synthesized by replacing the single main chain polymethylhydrosiloxane with reactive ladderlike polyhydrosilsesquioxane copolymers. Because of the interaction between polydimethylsilo...Heat-resistant silicone gels were synthesized by replacing the single main chain polymethylhydrosiloxane with reactive ladderlike polyhydrosilsesquioxane copolymers. Because of the interaction between polydimethylsiloxane chains and the ladderlike polysilsesquioxanes chains, the cyclization of the polydimethylsiloxane chains is hindered. The high thermal stability of the ladderlike polymers can improve the thermal stability of the silicone gels without sacrificing their good comprehensive properties.展开更多
A novel soluble ladderlike polysilsesquioxane containing reactive ester groups (Ester-T) was synthesized for the first time by stepwise coupling polymerization including preammonolysis, controlled hydrolysis and polyc...A novel soluble ladderlike polysilsesquioxane containing reactive ester groups (Ester-T) was synthesized for the first time by stepwise coupling polymerization including preammonolysis, controlled hydrolysis and polycondensation. The monomer, 3-trichlorosilylpropoxy 4-acetoxybenzoate (M), was synthesized by hydrosilylation of allyloxy 4-acetoxybenzoate with trichlorosilane in the presence of dicyclopentadienylplatinum (II) chloride (Cp2PtCl2) catalyst. Combination of FTIR, H-1-NMR, C-13-NMR, Si-29-NMR, XRD, DSC, TGA and VPO methods was used to demonstrate that the polymer obtained has an ordered ladderlike structure. The synthesized Ester-T may have promising applications as a precursor of advanced functional polymers.展开更多
A novel soluble and reactive amide-bridged ladderlike polyhydrosiloxane （ALPHS） was first synthesized by an amido H-bonding self-assembled template. ALPHS with molecular weight M^-a = 18300 has very highly ordered l...A novel soluble and reactive amide-bridged ladderlike polyhydrosiloxane （ALPHS） was first synthesized by an amido H-bonding self-assembled template. ALPHS with molecular weight M^-a = 18300 has very highly ordered ladderlike structure, which was confirmed by a sharp resonance absorption peak of [-Si（H）O2/2 ] moiety with the half peak width △1/2 〈 0.5 in^29Si-NMR spectrum. Presence of the reactive Si-H groups gives ALPHS an opportunity to further derive a variety of functional polymers by versatile Si-H reactions such as hydrosilylation, condensation, and so on.展开更多
Ladderlike polyhydroxypropylsilsesquioxane (HO-T) was synthesized by alcoholysis of ladderlike poly(3-propionyloxy-propyl)silsesquioxane. The HO-T was characterized by GPC, IR, NMR, DSC, TGA and X-ray diffraction meth...Ladderlike polyhydroxypropylsilsesquioxane (HO-T) was synthesized by alcoholysis of ladderlike poly(3-propionyloxy-propyl)silsesquioxane. The HO-T was characterized by GPC, IR, NMR, DSC, TGA and X-ray diffraction methods. Through hydrogen-bonding interaction, ladderlike polymer (HO-T) can form a supramolecular complex with somewhat regular structure.展开更多
Ladderlike polychloropropylsilsesquioxane (CP-T) was first synthesized by 'stepwise coupling polymerization'. The molecular weight of CP-T is as high as 1.7 x 10(5). It is a tough, elastic reactive ladderlike ...Ladderlike polychloropropylsilsesquioxane (CP-T) was first synthesized by 'stepwise coupling polymerization'. The molecular weight of CP-T is as high as 1.7 x 10(5). It is a tough, elastic reactive ladderlike polymer and has good heat-resistant and adhesive properties. CP-T can further react with many nucleophilic reagents to generate new ladderlike reactive polysilsesquioxanes, which can be used as potential precursors in the synthesis of functional ladderlike polymers.展开更多
Soluble, high molecular weight (MW) and ladderlike polyphenylsilsesquioxane (LPPSQ) and its copolymers, ladderlike random and block copolymethyiphenylsilsesquioxanes(LR-PMPSQ and LB-PMPSQ)have been prepared by preammi...Soluble, high molecular weight (MW) and ladderlike polyphenylsilsesquioxane (LPPSQ) and its copolymers, ladderlike random and block copolymethyiphenylsilsesquioxanes(LR-PMPSQ and LB-PMPSQ)have been prepared by preamminolysis, hydrolysis and polycondensation reactions. The preparation method can be carried out easily at the temperature below 95℃ with high yield of 95 %, instead of the conventional way by using high-boiling solvent and any reaction activator or by precipitation with methanol. Three kinds of ladderlike polymers have been characterized. The MW's of the polymers reached to 10~6 without noticeable gelling. The scheme for synthetic route has been proposed.展开更多
A new method for the preparation of a soluble ladderlike polymethylsilsesquioxane with high molecular weight ((?)=10~5—10~6) and low molecular weight distribution (D=Mw/Mn) in common solvents instead of the formerly ...A new method for the preparation of a soluble ladderlike polymethylsilsesquioxane with high molecular weight ((?)=10~5—10~6) and low molecular weight distribution (D=Mw/Mn) in common solvents instead of the formerly used toxic methylisobutylketone has been developed. The structure and macromolecular regularity were characterized by IR, X-ray diffraction, and ^(29)Si-NMR spectroscopy. The thermal property was studied by TGA and DSC.展开更多
Two kinds of fishbone-like, β-diketone-based liquid crystalline polysilsesquioxanes(FBDKLCP'S), homopolymeric (H-FBDKLCP) and copolymeric (C-FBDKaLCP) have been first synthesized via the hydrosilylation reaction ...Two kinds of fishbone-like, β-diketone-based liquid crystalline polysilsesquioxanes(FBDKLCP'S), homopolymeric (H-FBDKLCP) and copolymeric (C-FBDKaLCP) have been first synthesized via the hydrosilylation reaction of a vinyl-terminated β-diketone with the homopolymeric ladderlike polyhydrosilsesquioxane (LPHSQ) and random copolymethylhydrosilsesquioxane (LRPMHSQ) respectively. These new kinds of FBDKLCP with M of 10~4 is thermotroic liquid crystalline polymer and its clearing temperatures T_i's and mesophase range △T's are much higher than those of the corresponding comb-like β-diketone liquid crystalline polysiloxane (DKLCP) by about 200℃. Similar results have been observed with the comparison of the two different structure Cu-coordinating compounds The significant increases in T_((?))'s and △T's of the FBDKLCP and Cu-FBDKLCP are mainly attributed to the great rigidity of the ladderlike polysilsesquioxane backbone.展开更多
基金The authors gratefully thank the National Natural Science Foundation of China (No. 29874034, 29992530, 29873060) and Dow Corning Corporation for their financial support.
文摘Fluorescence spectra of ladderlike polyphenylsilsesquioxane (LPPS) and ladderlike 1,4-phenylene-bridged polyvinylsiloxane (LPPVS) have been measured as a function of temperature (4-55 degreesC), in dilute tetrahydrofuran solution. The excimer (IF) to monomer (I-M) intensity ratio (I-E/I-M) of LPPS dilute solution shows a double linear Arrhenius plot with a break point ascribable to a transition temperature Tt. This behavior has not been found for single chain polyorganosiloxanes. When In/(E) of LPPS was plotted against 1/T, it also gave a double linear plot with one break point, which was found in single chain polyorganosiloxanes. The different behaviors between LPPS and single chain polyorganosiloxanes may be mainly attributed to the relatively rigid double-chain macromolecular backbone of LPPS. However, the 1n(I-E/I-M) of dilute LPPVS solution versus 1/T shows a simple linear variation with a positive slope which confirms our proposition. The difference between the fluorescence results of LPPS and those of LPPVS may possibly derive from their structure differences and cooperative motion in backbone chain bonds.
基金This work was supported by the National Natural Science Foundation of China(Nos.50273043,20204016,20174047)
文摘A novel ordered reactive oligomeric ladderlike copolymethyl-aminopropylsilsesquioxane(Me-AP-T),was successfully synthesized by an efficient hydrosilylation graft reaction of 1,1,1-trimethyl-N-2-propenyl-silanamine with a reactive oligomeric ladderlike copolymethyl-hydrosilsesquioxane(Me-H-T),which was prepared by“supramolecular chemistry-dictated stepwise coupling polymerization”process.FT-IR,~1H-and ^(29)Si-NMR spectra show that hydrosilylation reaction proceeds completely.Moreover,~1H-NMR spectra also indicate that both the molar ratios of≡SiMe group to Si—H and≡SiMe group to≡SiPrNH_2 are approximately 1:1 respectively based on the ratio of integrated resonance areas of the different groups.XRD analysis and ^(29)Si-NMR spectra are used for investigating the ladderlike structure of the polymers.A high T_g(128.38℃)of Me-AP-T shown in DSC measurement implies that the ordered reactive Me-AP-T macromolecules have much stiff chains.
基金This project was supported by Beijing National Laboratory of Structural Chemistry of Stable and Unstable Species.
文摘The high molecular ladderlike polyhydrosilsesquioxane （LPHSQ） and its copolymer, ladderlike random copolymethylhydrosilsesquioxane （LR-PMHSQ） and ladderlike block copolymethylsilsesqui-oxane（LB-PMHSQ） have been synthesized by a preaminolysis reaction of the corresponding trichlorosilane with 1 ,4-phenylene diamine（PDA） then by hydrolysis and polycondensation reactions The thermographs of these polymers measured by DSC method indicate that these macromolecular backbones are very rigid as seen from the DSC curves which are almost horizontal from room temperature until 350;without noticeable glass transition. The content of Si—H group in the polymers can be regulated by changing the composition of the two copolymerized monomers. So the ladderlike polymers including its copolymers can be the useful precursors for the functional polymers, especially such as fishbone-like liquid crystalline polymers.
基金This work was supported by Fund of Head of College of Chemistry,Shandong University.
文摘Blends of PC and PPSQ (A) with high M-w and good ladderlike regularity or PPSQ(B) with low M-w and more defective Si-atoms in its structure have been prepared by solution casting. The dispersed spheres (PPSQ(A)-rich) are unevenly dispersed in the continuous PC-rich phase and there is no phase-inversion as PPSQ(A) content increases when the percentage of PPSQ(A) is not more than 70%. PPSQ(B)-rich spheres are evenly dispersed in the continuous phase (PC-rich) and phase-inversion occurs when PPSQ(B) percentage is up to 70%. T-g of PPSQ(A)/PC or PPSQ(B)/PC at some compositions are lower than that of pure PC due to the enlarged free-volume of PC-rich phase because some spheres of rigid PPSQ chains are included in the PC-rich phase. PC and PPSQ(A) or PPSQ(B) are partially compatible. The compatibility of PC and PPSQ(B) is better than that of PC and PPSQ(A) with high M-w and good ladderlike regularity. Heat history has some influence on the T(g)s and compatibility of PPSQ(A)/PC and PPSQ(B)/PC blends.
基金This project is financially supported by Institute of Materials Research and Engineering, Singapore.
文摘Heat-resistant silicone gels were synthesized by replacing the single main chain polymethylhydrosiloxane with reactive ladderlike polyhydrosilsesquioxane copolymers. Because of the interaction between polydimethylsiloxane chains and the ladderlike polysilsesquioxanes chains, the cyclization of the polydimethylsiloxane chains is hindered. The high thermal stability of the ladderlike polymers can improve the thermal stability of the silicone gels without sacrificing their good comprehensive properties.
基金The authors are grateful to the National Natural Science Foundation of China(No.29874034),Dow Coming Corporation and Institute of Materials Research and Engineering,National University of Singapore for their financial supports.
文摘A novel soluble ladderlike polysilsesquioxane containing reactive ester groups (Ester-T) was synthesized for the first time by stepwise coupling polymerization including preammonolysis, controlled hydrolysis and polycondensation. The monomer, 3-trichlorosilylpropoxy 4-acetoxybenzoate (M), was synthesized by hydrosilylation of allyloxy 4-acetoxybenzoate with trichlorosilane in the presence of dicyclopentadienylplatinum (II) chloride (Cp2PtCl2) catalyst. Combination of FTIR, H-1-NMR, C-13-NMR, Si-29-NMR, XRD, DSC, TGA and VPO methods was used to demonstrate that the polymer obtained has an ordered ladderlike structure. The synthesized Ester-T may have promising applications as a precursor of advanced functional polymers.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.50073028,29974036,20174047).
文摘A novel soluble and reactive amide-bridged ladderlike polyhydrosiloxane （ALPHS） was first synthesized by an amido H-bonding self-assembled template. ALPHS with molecular weight M^-a = 18300 has very highly ordered ladderlike structure, which was confirmed by a sharp resonance absorption peak of [-Si（H）O2/2 ] moiety with the half peak width △1/2 〈 0.5 in^29Si-NMR spectrum. Presence of the reactive Si-H groups gives ALPHS an opportunity to further derive a variety of functional polymers by versatile Si-H reactions such as hydrosilylation, condensation, and so on.
基金This project is financially supported by National Natural Science Foundation of China (No. 29874034).
文摘Ladderlike polyhydroxypropylsilsesquioxane (HO-T) was synthesized by alcoholysis of ladderlike poly(3-propionyloxy-propyl)silsesquioxane. The HO-T was characterized by GPC, IR, NMR, DSC, TGA and X-ray diffraction methods. Through hydrogen-bonding interaction, ladderlike polymer (HO-T) can form a supramolecular complex with somewhat regular structure.
基金This project is financially supported by National Natural Science Foundation of China (No. 29874034).
文摘Ladderlike polychloropropylsilsesquioxane (CP-T) was first synthesized by 'stepwise coupling polymerization'. The molecular weight of CP-T is as high as 1.7 x 10(5). It is a tough, elastic reactive ladderlike polymer and has good heat-resistant and adhesive properties. CP-T can further react with many nucleophilic reagents to generate new ladderlike reactive polysilsesquioxanes, which can be used as potential precursors in the synthesis of functional ladderlike polymers.
文摘Soluble, high molecular weight (MW) and ladderlike polyphenylsilsesquioxane (LPPSQ) and its copolymers, ladderlike random and block copolymethyiphenylsilsesquioxanes(LR-PMPSQ and LB-PMPSQ)have been prepared by preamminolysis, hydrolysis and polycondensation reactions. The preparation method can be carried out easily at the temperature below 95℃ with high yield of 95 %, instead of the conventional way by using high-boiling solvent and any reaction activator or by precipitation with methanol. Three kinds of ladderlike polymers have been characterized. The MW's of the polymers reached to 10~6 without noticeable gelling. The scheme for synthetic route has been proposed.
文摘A new method for the preparation of a soluble ladderlike polymethylsilsesquioxane with high molecular weight ((?)=10~5—10~6) and low molecular weight distribution (D=Mw/Mn) in common solvents instead of the formerly used toxic methylisobutylketone has been developed. The structure and macromolecular regularity were characterized by IR, X-ray diffraction, and ^(29)Si-NMR spectroscopy. The thermal property was studied by TGA and DSC.
文摘Two kinds of fishbone-like, β-diketone-based liquid crystalline polysilsesquioxanes(FBDKLCP'S), homopolymeric (H-FBDKLCP) and copolymeric (C-FBDKaLCP) have been first synthesized via the hydrosilylation reaction of a vinyl-terminated β-diketone with the homopolymeric ladderlike polyhydrosilsesquioxane (LPHSQ) and random copolymethylhydrosilsesquioxane (LRPMHSQ) respectively. These new kinds of FBDKLCP with M of 10~4 is thermotroic liquid crystalline polymer and its clearing temperatures T_i's and mesophase range △T's are much higher than those of the corresponding comb-like β-diketone liquid crystalline polysiloxane (DKLCP) by about 200℃. Similar results have been observed with the comparison of the two different structure Cu-coordinating compounds The significant increases in T_((?))'s and △T's of the FBDKLCP and Cu-FBDKLCP are mainly attributed to the great rigidity of the ladderlike polysilsesquioxane backbone.
