A one-pot procedure for the synthesis of polyethylene tethered on multi-walled carbon nanotubes by in situ ethylene copolymerization with an olefin-type comonomer, α-alkene functionalized multi-walled carbon nanotubes (MW — CH = CH₂) is reported. The covalent linkage between polyethylene and multi-walled carbon nanotubes is demonstrated. The MWCNTs are chemically oxidized first by a strong oxidizing agent and then functionalized with chlorocarbonyl groups (MW—COCl) via reacting with thionyl chloride. The MW—CH=CH₂ are obtained by esterification of ω-undecylenyl alcohol with MW—COCl. The MW—CH=CH₂ may serve as olefin-type comonomers to further synthesize core-shell structured copolymers with a multi-walled carbon nanotubes core grafted with side chains of polyethylene via rac-(en)(THInd)₂ZrCl₂ copolymerization catalyst. The core-shell structured nanocomposites were characterized by means of ¹H-NMR, SEM, FTIR and TGA. The results confirmed the formation of polyethylene chains growing from the surface of multi-walled carbon nanotubes.

The dynamics of polymer chains in layered silicate/polystyrene nanocomposites was studied by anelastic spectroscopy. Two thermal activated peaks (α and α′peaks) appeared when the specimens were heated to a high temperature and they were related to glass transition and liquid-liquid transition, respectively. The activation energy was calculated based on Arrhenius equation and it showed that the activation energy of glass transition (E_g) is much higher than that of liquid-liquid transition (E_ll). Furthermore, the most interesting result for the activation energy was that there were two contrary trends for E_g and E_ll, E_g decreased and E_ll increased with the addition of clay platelets. The fragile parameter was analyzed and the variation of fragile parameters for the two transitions was also contrary to each other with the addition of clay platelets. All the results indicated that the confinement effect of clay platelets on the dynamics of polymer chain was scale dependent, and perhaps, the two transitions were produced by different mechanisms.

A new type of nanofibrous structure from chitosan bearing carboxymethyl-β-cyclodextrin (CS-g-β-CD) as a novel drug delivery system was synthesized by grafting carboxymethyl-β-cyclodextrin (CM β-CD) onto chitosan (CS) in the presence of water soluble 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as the condensing agent and N-hydroxysuccinimide (NHS). Defect free mats containing CS-g-β-CD have been fabricated using electrospinning of an aqueous solution of poly(vinyl alcohol) (PVA)/CS-g-β-CD blends. The morphology and diameter of the electrospun nanofibers were examined by scanning electron microscopy (SEM). The average fiber diameter was in the range of 130−210 nm. SEM images showed that the morphology and diameter of the nanofibers were mainly affected by weight ratio of the blend at constant applied voltage. The results revealed that increasing CS-g-β-CD content in the blends decreases the average fiber diameter. It was observed that the PVA/CS-g-β-CD nanofibrous mat provided a slower release of the entrapped drug in compare to PVA/CS nanofibrous mat.

A novel flame retardant (DAPSiO), containing silicon and nitrogen, was synthesized by using dichlorodiphenylsilane, γ-chloropropyl methyl dimethoxysilane and 1,2-ethanediamine. DAPSiO was used together with potassium-4-(phenylsulfonyl)benzenesulfonate (KSS) to prepare a flame-retardant system for polycarbonate (PC). The structure of DAPSiO was characterized by Fourier transform infrared spectroscopy (FTIR), and ¹H-NMR tests. Flammability and thermal behaviors of PC/KSS/DAPSiO systems were estimated by limited oxygen index (LOI), vertical burning test (UL-94) and thermogravimetric analysis (TGA) tests. The results showed that the flame retardancy and thermal stability of PC/KSS system were improved with the addition of DAPSiO. When 1 wt% DAPSiO and 0.5 wt% KSS were incorporated, the LOI value of PC was found to be 44, and class V-0 of UL-94 test was passed. The scanning electron microscopy (SEM) and FTIR indicated that PC/KSS/DAPSiO system held a more cohesive and denser char structure when compared with pure PC and PC/KSS system.

Three kinds of novel aromatic diamine-based benzoxazines containing naphthalene, propane-2,2-diyldibenzene and neopentyl groups in the backbone, respectively (designated as BAPNCP, BAPBACP and BAPNPGCP, respectively), were synthesized and characterized. In addition, the effects of backbone structures on curing behaviors of the monomers and thermal and flammability properties of the resulting polymers were systematically studied. The results indicated that BAPNPGCP displayed the highest enthalpy of the curing reaction associated with the ring-opening of benzoxazine, which was due to the effect of benzoxazine ring content per unit mass. Interestingly, the 5 wt% weight loss temperature and char residue after thermogravimetric test for poly(BAPNPGCP) were 8 ℃ and 7% higher than those of poly(BAPBACP). Meanwhile, the total heat release of poly(BAPNPGCP) was less than half of that for poly(BAPBACP), indicating the substantial effect of benzoxazine ring content on flammability and char formation. Furthermore, it was found that poly(BAPNCP) gave the best thermal stability and flame retardancy, which was due to the synergistic effect between naphthalene group and benzoxazine ring content. This study provides new insight into the curing behavior of benzoxazine and further understanding on the high performance of polybenzoxazine.

The interaction of a new neutral polymeric bonding agent (NPBA) containing N-Vinylpyrrolidone units with two types of oxidizers (ammonium perchlorate and Keto-RDX) was investigated by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). NPBA forms a layer of film on the surface of oxidizers. The paper gives hypothetical mechanisms for improving significantly mechanical properties by addition of the neutral polymeric bonding agent (NPBA).

This work focused on the effect of nanocrystalline cellulose (NCC) on the curing characteristics, aging resistance and thermal stability of natural rubber (NR) reinforced with carbon black (CB). Sharing the same fillers loading of 45 parts per hundred rubber (phr), NR/NCC/CB composites with different NCC/CB ratios (i.e. 0/45, 5/40, 10/35, 15/30, 20/25 phr) were prepared and analyzed. Resorcinol and hexamethylene tetramine (RH), acting as the modifier in NR/NCC interface, was also discussed for its influence. The result showed that an relatively higher ratio of NCC/CB led to a lower torque, a shorter cure time (T₉₀), a slightly longer scorch time (T₁₀) and a bigger vulcanization rate constant (K). This tendency suggested that the existence of NCC accelerated the vulcanization process. Additionally, modified by RH, NR/NCC/CB compounds exhibited a short T₁₀ and a elevated torque. And a moderate RH content would lower the E_a of vulcanization. A 10 phr substitute of CB by NCC can help to improve aging resistance in terms of mechanical properties. In a high temperature aging condition, composites with 10 phr NCC also performed the highest storage modulus (G′) among composites tested. A moderate NCC content contributed to the best retention of G′ after high temperature aging, so did the incorporation of RH. With the partial replacement of CB by NCC, the temperature of 5% weight-lose had a slight drop and the apparent crosslink density showed a decrease. Thanks to the interaction of RH with both NR and NCC, composites showed an improvement in apparent crosslink density after modified by RH.

A research has been carried out to investigate the mechanical properties of composites made by hybridizing sugar palm fibre (Arenga pinnata) with glass fibre into an unsaturated polyester matrix. Hybrid composites of glass/sugar palm fibre were fabricated in different weight ratios of strand mat glass fibres: sugar palm fibres 4:0, 4:1, 4:2, 4:3, 4:4, and 0:4. The hybrid effects of glass and sugar palm fibre on tensile, flexural and impact properties of the composites were evaluated according to ASTM D5083, ASTM D790 and ASTM D256 respectively. Results have been established that properties of hybrid glass/sugar palm composites such as tensile strength, tensile modulus, elongation at break, toughness, flexural strength, flexural modulus and impact strength are a function of fibre content. The failure mechanism and the adhesion between fibres/matrix were studied by observing the scanning electron micrographs of impact fracture samples. In general, the incorporation of both fibres into unsaturated polyester matrix shows a regular trend of increase in the mechanical properties.

The branching generation during the free radical copolymerization of chain transfer monomer p-vinyl benzene sulfonyl chloride (VBSC) with styrene was investigated by a simple mathematic model. Chain transfer constant of VBSC was determined to be around 0.3 by fitting the ¹H-NMR monitored experimental results with a mathematic model. According to the theoretical analysis, the obtained poly(VBSC) and its copolymers were substantiated to have a grafting-like main chain with residual pendent sulfonyl chloride groups after consuming most of the vinyl groups. The copolymerization results of VBSC with styrene at varied feed ratios demonstrated that conversion of sulfonyl chloride groups was lower than that of the monomer, which was in agreement with the theoretical results. The glass transition temperature, number average molecular weight and distribution of those obtained polymers were primarily investigated. Comparing with other chain transfer monomers, VBSC has a chain transfer constant much closer to unity therefore a more branched polymer is expected. Additionally, the branched polystyrene with residual sulfonyl chloride groups is hopefully to be further used as ATRP macroinitiators or reactive intermediates to synthesize functional polymers with complex structure.

An NLO hyperbranched polymer (HP1) derived from both "H"-type and star-type chromophores was synthesized successfully for the first time with high yield via one-pot "A₂ + B₃" Suzuki polymerization reaction. Isolation chromophore was also introduced to further improve its performance. Although under the test conditions, the films of HP1 could not be poled completely, it still demonstrated satisfactory macroscopic NLO effect with the second harmonic generation (SHG) coefficient d₃₃ value of 36 pm/V.

Crystallization of natural rubber (NR) was investigated in different morphology for NR/styrene butadiene rubber (SBR) blend and NR/polystyrene-(b)-polyisoprene (SI)/polystyrene (PS) blend. A purified NR (PC-TE) was prepared from pale crape via transesterification. In the blends, PC-TE formed various morphologies; that is, matrix phase, island phase and continuous phase with a nano-scale, respectively, in dependence upon the ratio of the rubbers. The crystallization rate of the blends was also significantly associated with the morphology of the rubbers.

A new conjugated hyperbranched polymer (hb-TFO) containing tetraphenylethylene (TPE) units, a famous aggregation-induced emission (AIE) active group, as the core, was synthesized successfully with modest yield via one-pot Suzuki polymerization reaction. Thanks to the introduction of TPE moieties, hb-TFO exhibited aggregation-enhanced emission (AEE) property, and could work as explosive chemosensor with high sensitivity. The polymeric light-emitting diode (PLED) device was fabricated to investigate its electroluminescent property, and hb-TFO demonstrated a maximum luminance efficiency of 0.22 cd/A and a maximum brightness of 545 cd/m² at 15.9 V.

Poly(3-alkyl)pyrroles containing phosphonic acid groups with different alkyl segment lengths were chemical synthesized and the properties were measured by FTIR and UV-Vis spectroscopy. FTIR and UV-Vis results showed that the synthesized polymers were in a low doping level through chemical polymerization. By spin-coating on the surface of substrates, the polymer can be used as a humidity sensor. The change of DC electric current of the polypyrroles varies with the chain length of the alkyl substituents. The capacitance increases with the increase of the humidity and resistance decreases with the increase of humidity. This result is different from that of polypyrrole without alkyl substituents due to the influence of the phosphonic acid group. The sensor showed the resistive-type at high relative humidity, and the capacitivetype at the low relative humidity. The sensor exhibited very fast response to the change of environment humidity.

To better investigate the degradation and biocompatibility of waterborne biodegradable polyurethanes for tissue engineering, a series of new waterborne biodegradable polyurethanes (PEGPUs) with low degree of crosslinking was synthesized using IPDI, BDO and L-lysine as hard segments, PCL and PEG as soft segment. The bulk structures and properties of the prepared polyurethanes were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), tensile mechanical tests and water contact angle (WCA) measurements. The degree of microphase separation was slightly improved because of the lowered crosslinking degree of these PEGPUs in comparison with the high cross-linking degree samples, leading to good mechanical properties, as indicated by DSC and stress-strain data. Moreover, biodegradability of the polyurethanes was evaluated in phosphate buffer solutions (PBS) under different pH values and enzymatic solution at pH 7.4 through weight loss monitoring. The results suggested that the degradation of these PEGPUs was closely related to their bulk and surface properties. And the degradation products didn’t show apparent inhibition effect against fibroblasts in vitro. These studies demonstrated that the waterborne biodegradable polyurethanes could find potential use in soft tissue engineering and tissue regeneration.