Synthesis and characterization of aromatic polymers containing pendant silyl groups. I. Polyarylates

Polyarylates containing pendant silyl group were prepared by the phase-transfer catalyzed, two-phase polycondensations of 2,2-bis (4-hydroxyphenyl) propane with corresponding dicarbonyl chlorides such as 2-trimethylsilylterephthaloyl chloride, 5-trimethylsilylisophthaloyl chloride, 5-dimethylphenylsilylisophthaloyl chloride, and 5-triphenylsilylisophthaloyl chloride. The resulting amorphous polyarylates with glass transition temperatures of 163–214°C had inherent viscosities in the range of 0.41–0.95 dL/g. These polyarylates were readily soluble in common chlorinated hydrocarbons and it was possible to obtain transparent, flexible, and tough films from the polymer solutions. The prepared polyarylates showed fairly good thermal stabilities as well as tensile strengths, i.e., the tensile strengths of the cast films from chloroform solution were 6.0–6.7 kg/mm². And TGA data revealed 10% weight losses and residual weights at 800°C were 437–495°C and 27–40% under nitrogen atmosphere, respectively. © 1992 John Wiley & Sons, Inc.     

Synthesis and characterization of new polymer systems containing very bulky tris(trimethylsilyl)methyl substituents as side chains

The 4-chloromethyl styrene (CMS) was copolymerized with different styrenic monomers such as methyl styrene, 4-methoxy styrene and α-methyl styrene by free radical polymerization method at 70 ± 1 °C using α,α^′-azobis(isobutyronitrile) (AIBN) as an initiator and the copolymers I, II and III collected respectively. The very bulky tris(trimethylsilyl)methyl {trisyl} substituents were covalently attached to the obtained copolymers with replacement of all the chlorine atoms in CMS units. The polymers, obtained in quantitative yields, were characterized by FT-IR, ¹H NMR and ¹³C NMR spectroscopy; differential scanning calorimetry (DSC) and GPC studies. All the polymers containing trisyl groups showed a high glass transition temperature (in the range 150-190 °C) in comparison with copolymers I-III (in the range 90-95 °C). The increase of the glass transition temperature reflects the substantial increase in rigidity of new polymers bearing very bulky substituents in side chains.     

Influence of graphene reinforcement in conductive polymer: Synthesis and characterization

Lightweight conductive polymers are considered for lightning strike mitigation in composites by synthesizing intrinsically conductive polymers (ICPs) and by the inclusion of conductive fillers in insulating matrices. Conductive films based on polyaniline (PANI) and graphene have been developed to improve through‐thickness conductivity of polymer composites. The result shows that the conductivity of PANI enhanced by blending polyvinylpyrrolidone (PVP) and PANI in 3:1 ratio. Conductive composite thin films are prepared by dispersing graphene in PANI. The conductivity of composite films was found to increase by 40× at 20 wt% of graphene inclusion compared with PVP and PANI blend. Fourier‐transform‐infrared (FTIR) spectra confirmed in situ polymerization of the polymer blend. The inclusion of graphene also exhibits an increase in Tg by 21°C. Graphene additions also showed an increase in thermal stability by approximately 148°C in the composite films. The mechanical result obtained from DMA shows that inclusion of graphene increases the tensile strength by 48% at 20 wt% of graphene reinforcement. A thin, highly conductive surface that is compatible with a composite resin system can enhance the surface conductivity of composites, improving its lightning strike mitigation capabilities.     

Synthesis and characterization of aromatic polymers containing pendant silyl groups. II. Aromatic polyamides

In order to improve the solubility of aromatic polyamides without significant loss of thermal stability, synthesis of aromatic polyamides containing pendant silyl groups was carried out by direct polycondensation of silylated aromatic diacids such as 2-trimethylsilylterephthalic acid (TSTA), 2,5-bis (trimethylsilyl) terephthalic acid (BTSTA), 5-trimethylsilylisophthalic acid (TSIA), 5-dimethylphenylsilylisophthalic acid (DMSIA), and 5-triphenylsilylisophthalic acid (TPSIA) with various aromatic diamines. The resulting polyamides had inherent viscosities in the range of 0.18–1.10 dL/g and showed improved solubilities toward aprotic polar solvents such as NMP, DMF, DMSO, etc. The prepared aromatic polyamides exhibited fairly good thermal stabilities, which were almost comparable to those of corresponding nonsubstituted aromatic polyamides. That is, thermogravimetric analysis (TGA) data revealed 10% weight losses at 358–500°C and residual weights at 700°C were 46–67% under nitrogen atmosphere. © 1992 John Wiley & Sons, Inc.     

Synthesis and characterization of new polyimides containing pendent pentadecyl chains

A new unsymmetrical aromatic diamine, viz., 4-pentadecylbenzene-1,3-diamine was synthesized through a series of reaction steps starting from 3-pentadecylphenol. 4-Pentadecylbenzene-1,3-diamine was employed to synthesize a series of new polyimides by one-step polycondensation in m-cresol with four commercially available aromatic dianhydrides, viz., 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 4,4′-oxydiphthalic anhydride (ODPA) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA). Inherent viscosities of resulting polyimides were in the range 0.33-0.67 dL/g and number average molecular weights were in the range 14,700-52,200 (GPC, polystyrene standard). Polyimides containing pendent pentadecyl chains were soluble in organic solvents such as chloroform, m-cresol, N,N-dimethylacetamide (DMAc), 1-methyl-2-pyrrolidinone (NMP), pyridine and nitrobenzene. Strong and flexible films of polyimides could be cast from their chloroform solutions. Polyimides exhibited glass transition temperature in the range 158-206 °C. The temperature at 10% wt. loss (T₁₀), determined by TGA in nitrogen atmosphere, of polyimides was in the range 470-480 °C indicating good thermal stability.     

Synthesis, characterization and thermal degradation of 8-hydroxyquinoline-guanidine-formaldehyde terpolymer

Terpolymer (8-HQGF) has been synthesized using the monomers 8-hydroxyquinoline, guanidine, formaldehyde in 1:1:2 molar proportions. The structure of 8-HQGF terpolymer has been elucidated on the basis of elemental analysis and various physicochemical techniques, i.e. UV-Visible, FTIR-ATR and ¹H NMR spectroscopy. Detailed thermal degradation study of the new terpolymer has been carried out to ascertain its thermal stability. Thermal degradation curve is discussed which shows two decomposition steps (265-475 °C and 540-715 °C). Sharp-Wentworth and Freeman-Carroll methods have been used to calculate activation energies and thermal stability. The activation energy (E_a) calculated by using the Sharp-Wentworth (21.98 kJ/mol) has been found to be in good agreement with that calculated by Freeman-Carroll (23.57 kJ/mol) method. Thermodynamic parameters such as free energy change (ΔF), entropy change (ΔS), apparent entropy change (S^∗) and frequency factor (Z) have also been evaluated on the basis of the data of Freeman-Carroll method. The order of reaction (n) is found out to be 0.9979.     

Synthesis and characterization of copolymaleimides containing 4‐cyanobiphenyl‐based side groups for nonlinear optical applications

We report the synthesis of a nematic copolymer, P(CBMS‐co‐M₃), prepared by free radical polymerization of an equimolecular mixture of p‐(4‐cyanobiphenyl‐4′‐yloxy)methylstyrene (CBMS) and N‐[3‐(4‐cyanobiphenyl‐4′‐yloxy)propyl]maleimide (M₃) and two isotropic alternating copolymers, P(S‐alt‐M_n) (n = 3,6) prepared by chemical modification of poly(styrene‐alt‐maleimide), P(S‐alt‐M), by n‐(4‐cyanobiphenyl‐4′‐yloxy)alkan‐1‐ol. These copolymaleimides were characterized by NMR, DSC, and optical microscopy. Some corona poling experiments were performed and the second harmonic coefficients d₃₁ and d₃₃ were measured. It was shown that one can gain in net polar ordering by starting with a liquid crystalline system. The ratio d₃₃/d₃₁ was much larger than 3, in agreement with the molecular statistical models for electric field poling of liquid crystals. At ambient conditions, changes of d₃₃ and d₃₁ are 15% over 325 days. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 513–524, 1999     

Synthesis and structural characterization of carbon-centered tris(pentafluorophenyl)silyl derivatives

A general method for the synthesis of carbon-centered tris(pentafluorophenyl)silyl derivatives (RSi(C₆F₅)₃) by reaction of trichlorosilanes (RSiCl₃) with pentafluorophenylmagnesium bromide was described. The crystal structures of obtained compounds were studied by X-ray diffraction analysis (7 structures). The peculiarities of crystal packing were analyzed by means of DFT calculations.     

Synthesis and characterization of thermoresponsive hydrogels cross-linked with chitosan

Hydrogels composed of N-isopropylacrylamide (NIPAAm) and acrylic acid (AAc) were prepared by redox polymerization with degradable chitosan cross-linkers. Chitosan degradable cross-linkers were synthesized by the acrylation of the amine groups of glucosamine units within chitosan and characterized with ¹H NMR. With the chitosan cross-linkers, loosely cross-linked poly(N-isopropylacryamideco-acrylic acid) [P(NIPAAm-co-AAc)] hydrogels were prepared, and their phase transition behavior, lower critical solution temperature (LCST), water content and degradation properties were investigated. The chitosan cross-linked P(NIPAAm-co-AAc) hydrogels were pliable and transparent at room temperature. The LCST could be adjusted at 32∼39°C by alternating the feed ratio. Swelling was influenced by NIPAAm/AAc monomer ratio, cross-linking density, swelling media, and temperature. All hydrogels with different feeding ratios contained more than 95% water at 25°C in the ultra pure water and phosphate-buffered saline (PBS, pH = 7.4 ± 0.1), and had a prospective swelling in the simulated gastric fluids (SGF, pH = 1.2) > 72.54%. In degradation studies, breakdown of the chitosan cross-linked P(NIPAAm-co-AAc) hydrogels was dependent on the cross-linking density. The chitosan cross-linked P(NIPAAm-co-AAc) hydrogels which can be tailored to create environmentally-responsive artificial extracellular materials have great potential for future use.      

低分子量聚合物电解质的合成与性能

研究了低分子量梳状聚合物电解质的合成方法及结构，性能。首先合成了不同分子量的甲基丙烯酸聚乙二醇单甲醚酯，并进一步合成了分子量一万左右的梳状聚合物电解质，结果表明：反应严格按照反应方程进行，精制产物是非晶的梳状聚合物，本聚合物体系均存在两个玻璃化转变温度，一个在100℃左右，归属为梳状聚合物主链的玻璃化转变，另一个在－20摄氏度以下，归属于侧链玻璃化转变，在室温下侧链可以运动，有利于电活性物质的迁移和扩散，并用超微电极研究了该电解质的行为。     

Synthesis and characterization of thermoresponsive hydrogels cross-linked with acryloyloxyethylaminopolysuccinimide

Biodegradable cross-linkers acryloyloxyethylaminopolysuccinimide (AEA-PSI) were obtained by microwave irradiation using maleic anhydride as materials. With AEA-PSI cross-linker, cross-linked poly(N-isopropylacrylamide-co-acrylic acid) [P(NIPAAm-co-AAc)] hydrogels were prepared, and their phase transition behavior, lower critical solution temperature (LCST), water content, thermodynamics stability, and enzymatic degradation properties were investigated. By alternating the NIPAAm/AAc molar ratio, hydrogels were synthesized to have LCST in the vicinity of 37 °C. The LCST of AEA-PSI-cross-linked P(NIPAAm-co-AAc) hydrogels was significantly influenced by monomer ratio of the NIPAAm/AAc but not by the cross-linking density within the polymer network. The water content of AEA-PSI-cross-linked P(NIPAAm-co-AAc) hydrogels was more than 90% even at 37 °C, which was controlled by the monomer molar ratio of NIPAAm/AAc, swelling media, and the cross-linking density. The thermodynamics stability was also characterized by thermogravimetry. In enzymatic degradation studies, breakdown of the AEA-PSI-cross-linked P(NIPAAm-co-AAc) hydrogels was dependent on the cross-linking density. Submitted to Colloid and Polymer Science, 2007-1-28.     

Poly(N-vinyl-2-pyrrolidone-maleic anhydride-styrene) grafted terpolymer: Synthesis,characterization, and bactericidal property evaluation against E. coli and S. epidermidis

Poly(N-vinyl-2-pyrrolidone-maleic anhydride-styrene) terpolymer was prepared using AIBN initiator with acetone as solvent. The terpolymer was grafted with anti-bacterial agents para-aminobenzoic acid and 2,4-dichlorophenol to introduce bactericidal activity to the terpolymer. The terpolymer and the grafted polymers were characterized by FTIR, ¹H-NMR, and ¹³C-NMR spectroscopic methods. Thermal properties were determined by differential scanning calorimetric technique and thermogravimetric analysis. The glass transition temperature was found to be 111°C (terpolymer), 150°C (VMS-G-PABA) and 130°C (VMS-G-DCP). Terpolymer starts degradation at 288°C and grafted terpolymers at 104°C (VMS-G-PABA) and 129°C (VMS-G-DCP), respectively. The anti-bacterial activity of grafted terpolymers were evaluated by the shake flask method against gram positive and gram negative bacteria E. coli and S. epidermidis. The grafted terpolymers showed effective inhibition against both the bacteria, the minimum inhibition concentration was observed to be 75 µg/mL and 80 µg/mL for VMS-G-PABA and 50 µg/mL for VMS-G-DCP against E. coli and S. epidermidis, respectively. The new polymers showed 90% bacterial growth inhibition at 200 µg/mL.     

Synthesis and characterization of aromatic poly(ether sulfone)s containing pendant sodium sulfonate groups

Poly(ether sulfone)s containing pendant sodium sulfonate groups were prepared by the aromatic nucleophilic substitution reaction of 4,4′-dichlorodiphenylsulfone ( 1 ) and sodium 5,5′-sulfonylbis (2-chlorobenzenesulfonate) ( 2 ) with bisphenols ( 3 ) in the presence of potassium carbonate in N,N-dimethylacetamide. A new monomer 2 containing the sodium sulfonate groups was synthesized by the sulfonation of 1 with fuming sulfuric acid. The polycondensation proceeded smoothly at 170°C and produced the desired poly(ether sulfone)s containing the sodium sulfonate with inherent viscosities up to 1.2 dL/g. The polymers were quite soluble in strong acid, dipolar aprotic solvents, m-cresol, and dichloromethane. The thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight losses of the polymers were observed in the range above 460°C in nitrogen atmosphere. Both the glass transition temperatures and hydrophilicity of the polymers increased with increasing their concentrations of sodium sulfonate groups. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of polymaleimides containing 4-cyanobiphenyl–based side groups for nonlinear optical applications

A new homologous series of SCLCPs containing the 4-cyanobiphenyl mesogenic group attached to the polymaleimide backbone through paraffinic spacers of two to eight methylene units have been prepared. All the polymers exhibit liquid crystalline behavior; specifically S_Ad- (or S_C-) like and nematic phases are observed. The glass transition temperature decreases from 150 to 43°C on increasing spacer length. The isotropization temperatures exhibit an odd–even effect on varying the length and parity of the spacer, in which the odd members exhibit the higher values. This is attributed to the change in the average shape of the side chain as the parity of spacer is varied. The isotropization temperatures (>300–120°C) and the mesophase thermal stabilities (190–60°C) are high. Comparison is made with polymers containing the same mesogenic group attached to backbones of decreasing rigidity. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2531–2546, 1998     

Synthesis of two new cage molecules containing trinitromethyl group

<正>Two new cage compounds,4-trinitroethyl-10-nitro-2,6,8,12-tetraacetylhexaazaisowurtzitane(3) and 4-trinitroethyl- 2,6,8,10,12-pentanitrohexaazaisowurtzitane(4),containing trinitromethyl group were synthesized by a novel method,and their structures were confirmed by IR,~1H NMR,MS and single crystal X-ray.DSC result shows that compound 4 has surprising thermal stability and could be a potential energetic compound.     

Synthesis and characterization of a biodegradable ABC triblock terpolymer as co‐delivery carrier of doxorubicin and DNA

This study is aimed to develop a well‐defined ABC triblock terpolymer, poly(ethylethylene phosphate)‐block‐poly(ε‐caprolactone)‐block‐poly[2‐(dimethylamino)ethyl methacrylate] (PEEP‐b‐PCL‐b‐PDMAEMA), for co‐encapsulating anticancer drug doxorubicin (DOX) and DNA to form polyplexes. The terpolymer is first synthesized via a combination of ring‐opening polymerization and atom‐transfer radical polymerization techniques, and characterized by ¹H NMR and gel permeation chromatography. Subsequently, the self‐assembly behavior of the terpolymer and the micelles loaded with DOX or DNA are investigated by dynamic light scattering, ζ potential, transmission electron microscopy, and gel retardation assay, respectively. In vitro release study reveals that much more DOX is released at pH 5.0 than that at pH 7.4 in the same period. The simultaneous delivery of DOX and green fluorescent protein (GFP)‐labeled DNA is studied by a fluorescence microscope and the results demonstrate that both drug and GFP–DNA can be efficiently delivered into HeLa cells. This system presents a practical and promising carrier for the co‐delivery of drugs and genes. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3005–3016     

Synthesis and characterization of new polydiolcitrates with tunable properties

Polydiolcitrates are an emerging class of biocompatible polyesters with a great potential in the field of biomedicine and packaging for food and drug materials. In this work, a new type of (co‐)polydiolcitrates made of citric acid (CA) and ethylene glycol (EG) and/or poly(ethylene glycol) (PEG) is investigated. By varying both the EG/PEG and the CA/diol molar ratios, materials exhibiting very different swelling behavior, mechanical and thermal properties are obtained. In particular, the substitution of EG segments with longer and flexible PEG ones results in an increase in crosslinking density, with remarkable effects on swelling capacity, glass transition temperature, and Young modulus. Moreover, polyesters with CA/diol molar ratio equal to 1:1 exhibit shape memory properties, with full capacity of keeping the temporary shape and high capacity of recovering the original shape. This work demonstrates that the appropriate choice of polyester composition allows modulating the sample properties, that permits to these materials to cover a wide range of possible applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3713–3720     

Poly(L-lactide) macrodiols (HOPLLAOH): Influence of linear alkyl diols as initiators: Synthesis and characterization

A series of α,ω-hydroxy telechelic poly(L-lactide)s (HOPLLAOHs) were synthesized by ring-opening polymerization (ROP) of L-lactide (L-LA) using tin octoate [Sn(Oct)₂] as catalyst and a family of linear alkyl diols as initiators [HO–[CH₂]_m–OH, where m = 2, 4, 6, 8, 10, and 12]. A systematic analysis of these HOPLLAOHs species in terms of their thermal properties was realized by DSC. In this sense, the linear alkyl group had an important influence on the glass transition temperature (T_g); a relatively high content of alkyl group on the HOPLLAOH increased the flexibility of the polyester, evidenced by a value of T_g inversely proportional to the weight percent of the alkyl group. Besides, the alkyl groups had an effect on the crystallization temperature (T_c), melting temperature (T_m), and crystallinity (x_i). Additionally, HOPLLAOHs were characterized by ¹H and ¹³C NMR, FT-IR, MALDI-TOF, and GPC.     

聚乙交酯-丙交酯-己内酯三元无规共聚物及其电纺膜的制备与表征

以左旋丙交酯、乙交酯和己内酯为原料,辛酸亚锡为催化剂,在真空条件下经本体熔融开环聚合,制备了三元无规共聚物(P),其结构和性能经1H NMR,IR,DSC和粘度表征。实验结果表明:P的玻璃化转变温度可通过单体的投料比调控;采用静电纺丝法可方便地获得共聚物亚微米纤维膜。