Various semi-interpenetrating polymer network (semi-IPN) hydrogels composed of pore-forming agent polyethylene glycol (PEG), acrylic acid (AA) and acrylamide (AM) were prepared by using free radical polymerization with a two-step method. The chemical structures of the synthesized hydrogels were characterized by FTIR spectroscopy and the morphologies were studied by scanning electron microscopy (SEM) method. The swelling properties, such as the pH-responsive behavior, salt sensitivity, oscillatory swelling/de-swelling behaviors in different solutions with various pH values and self-oscillating behaviors in bath pH oscillator were investigated in detail. The results revealed that the prepared hydrogels exhibited high pH sensitivity and excellent salt sensitivity when the pH values of the medium changes from 3.0 and 7.0 and well reversible properties by undergoing a number of swelling/de-swelling recycles. In particular, the hydrogels exhibited self-oscillation behavior in a closed system containing BrO3--SO32--Fe(CN)64--H+. This study may create a new possibility as biomaterial for new self-walking actuators and other devices.

Poly(lactide-co-glycolide)-poly(ethylene glycol)-poly(lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymer was synthesized through the ring-opening polymerization of LA and GA with PEG as macroinitiator and stannous octoate as catalyst. The amphiphilic copolymer self-assembled into micelles in aqueous solutions, and formed hydrogels as the increase of temperature at relatively high concentrations ( 15 wt%). The favorable degradability of the hydrogel was confirmed by in vitro and in vivo degradation experiments. The good cellular and tissular compatibilities of the thermogel were demonstrated. The excellent adhesion and proliferation of bone marrow mesenchymal stem cells endowed PLGA-PEG-PLGA thermogelling hydrogel with fascinating prospect for cartilage tissue engineering.

To improve the dispersion of silica in polypropylene (PP) matrix and to avoid physical loss of the antioxidants, nanosilica with dendric polyamidoamines on the surface (SG-PAMAM) was synthesized by using divergent method. Then nanosilica-immobilized antioxidant (SG-PAMAM-AO) was prepared by grafting 2,6-di-tert-butyl-4-aminophenol which was derived from 2,6-di-tert-butyl-4-phenol (AO). The SG-PAMAM-AO was added into PP by melt mixing to study the aging property. The oxidation induction time of PP/SG-PAMAM-AO and PP/AO compounds was measured. It was found that the antioxidant property of the SG-PAMAM-AO was superior to that of AO. According to the changes of carbonyl absorption before and after photo-thermal aging, the photo-thermal oxidative stability of PP/SG-PAMAM-AO was much higher than that of PP, PP/SG-PAMAM and PP/AO.

Polyimides (PI) with different side chains in structure were synthesized by copolycondensation of pyromelliticmdianhydride (PMDA) with 3,5-diamino-(4'-methane acid hexyl ester) phenyl-benzamide (C6-PDA), (4-butoxy-biphenol)-3', 5'-diaminobenzoate (C4-BBDA) and 3, 5-diamino-benzoic acid decyl ester (C10-DA) named PI-PDA, PI-C4, PI-DA, respectively. The lengths of side chains of PI-PDA and PI-DA are as similar as that of PI-C4. Through the pretilt angle tests it is demonstrated that neither the structure of side chains nor the rubbing process could make an obvious difference on vertical alignment property when the lengths of the side chains are similar, standing at around 1.6 nm. The measurement of surface energy of PI surfaces further proved this result. The result of the X-ray photo-electron spectroscope measurement indicated that the side chains of PIs stretched out from the polymer bulk phase and accumulated on the surface.

The aim of this paper is to report the effect of the addition of cellulose nanocrystals (CNCs) on the mechanical, thermal and barrier properties of poly(vinyl alcohol)/chitosan (PVA/Cs) bio-nanocomposites films prepared through the solvent casting process. The characterizations of PVA/Cs/CNCs films were carried out in terms of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA and DTG), oxygen transmission rate (OTR), and tensile tests. TEM and SEM results showed that at low loading levels, CNCs were dispersed homogenously in the PVA/Cs matrix. The tensile strength and modulus in films increased from 55.1 MPa to 98.4 MPa and from 395 MPa to 690 MPa respectively, when CNCs content went from 0 wt% to 1.0 wt%. The thermal stability and oxygen barrier properties of PVA/Cs matrix were best enhanced at 1.0 wt% of CNCs loading. The enhanced properties attained by incorporating CNCs can be beneficial in various applications.

A supercritical carbon dioxide (ScCO2) assisted phase inversion was developed to produce microporous poly(vinylidene fluoride) (PVDF) membranes whose morphology characteristics arise from both liquid-liquid demixing and solid-liquid demixing (crystallization). This result was confirmed by Fourier transform infrared spectroscopy (FTIR), from which both and crystals were found. As revealed by contact angle experiment, the PVDF membranes prepared via ScCO2 assisted phase inversion were more hydrophobic compared with the control membrane produced via conventional immersion-precipitation technique. In particular, the sample with 15 wt% PVDF prepared at 45 ℃ and 13 MPa exhibited a contact angle of 142, which was mainly caused by the multilevel micro- and nano- structure. The effects of polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP) and lithium chloride (LiCl) on the structures and crystal form were investigated. PVP promoted the formation of phase crystal form, while PEG boosts the evolution of phase. LiCl restrained the crystallization degree of PVDF membrane under ScCO2.

An easy method is presented to fabricate monodisperse magnetic macroporous polymer beads (MMPBs). Water-in-oil high internal phase emulsion (HIPE) is prepared by emulsifying aqueous iron ions solution in an oil phase containing monomers. The HIPE is introduced into a simple microfluidic device to fabricate monodisperse (water-in-oil)-in-water double emulsion droplets. The droplets serve as microreactors to synthesize Fe3O4 nanoparticles and are on-line polymerized to form MMPBs. The prepared MMPBs display uniform size, interconnected porous structure, superparamagnetic behavior and uniform distribution of Fe3O4 in polymer matrix. The MMPBs are characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM). We believe that this method is a universal technique in preparing macroporous nanocomposite beads.

Porous polymer beads (PPBs) containing hierarchical bimodal pore structure with gigapores and meso-macropores were prepared by polymerization-induced phase separation (PIPS) and emulsion-template technique in a glass capillary microfluidic device (GCMD). Fabrication procedure involved the preparation of water-in-oil emulsion by emulsifying aqueous solution into the monomer solution that contains porogen. The emulsion was added into the GCMD to fabricate the (water-in-oil)-in-water double emulsion droplets. The flow rate of the carrier continuous phase strongly influenced the formation mechanism and size of droplets. Formation mechanism transformed from dripping to jetting and size of droplets decreased from 550 m to 250 m with the increase in flow rate of the carrier continuous phase. The prepared droplets were initiated for polymerization by on-line UV-irradiation to form PPBs. The meso-macropores in these beads were generated by PIPS because of the presence of porogen and gigapores obtained from the emulsion-template. The pore morphology and pore size distribution of the PPBs were investigated extensively by scanning electron microscopy and mercury intrusion porosimetry (MIP). New pore morphology was formed at the edge of the beads different from traditional theory because of different osmolarities between the water phase of the emulsion and the carrier continuous phase. The morphology and proportion of bimodal pore structure can be tuned by changing the kind and amount of porogen.

A tin-oxygen coordination driving self-assembly was developed in the block copolymers containing organotin, which were prepared by the radical addition-fraction transfer (RAFT) method and characterized by the gel-permeation chromatography (GPC) and 1H-NMR. And the self-assemblies of these block copolymers with various chain length ratios in the different concentrations in CHCl3 were stable according to the results of DLS and TEM. Additionally, it was also given an insight investigation on the regulation of self-assembly of the block copolymers by adding dibutyltin dichloride and a possible mechanism was proposed.

The polyurethane, which was the subject of the constitutive research presented in the paper, was based on oligocarbonate diols Desmophen C2100 produced by Bayer. The constitutive modelling was performed with a view to applying the material as the inlay of intervertebral disc prostheses. The polyurethane was assumed to be non-linearly visco-hyperelastic, isotropic and incompressible. The constitutive equation was derived from the postulated strain energy function. The elastic and rheological constants were identified on the basis of experimental tests, i.e. relaxation tests and monotonic uniaxial tests at two different strain rates, i.e. = 0.1 min-1 and = 1.0 min-1. The stiffness tensor was derived and introduced to Abaqus finite element (FE) software in order to numerically validate the constitutive model. The results of the constants identification and numerical implementation show that the derived constitutive equation is fully adequate to model stress-strain behavior of the polyurethane material.

The effects of temperature and relative humidity on the hydrolytic degradation of poly(p-dioxanone) (PPDO) were investigated. The hydrolytic degradation behaviors were monitored by tracing the changes of water absorption, mechanical and crystalline properties, molecular weight and its distribution, surface morphologies, as well as infrared absorption peaks and hydrogen chemical shifts during the degradation. It is found that the water absorption increases whilst the intrinsic viscosity, tensile strength and elongation at break decrease as the temperature or relative humidity increases. With degradation time growing, the molecular weight drops and its distribution broadens. The crystallinity of PPDO has a tendency to increase at first and then to decrease, while the crystalline structure is not significantly changed. At the same time, some cracks are observed on the surface and keep growing and deepening. All results show that temperature plays more significant roles than relative humidity during the degradation. The analyses of Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy reveal that the degradation of PPDO is a predominant hydrolysis of ester linkages.

The morphological changes of ABA amphiphilic triblock copolymer micelles in dilute solution were systematically studied by tuning the solvent property using self-consistent field simulation. The solvent property was tuned by changing the Flory-Huggins interaction parameters between each type of blocks and solvent, respectively. The simulation results show that by changing the solvent properties, a series of micelle morphologies such as vesicle, cage-like, ring-shaped, rod-like and spherical micelle morphologies can be obtained. Variations of the free energy of the solution system and the surface area of micelles with the Flory-Huggins interaction parameters were calculated to better understand the effect of solvent property on micelle morphologies. In addition, a phase diagram showing the morphological changes of micelles with the Flory-Huggins interaction parameters is provided.

The cationic folic acid (CFA) was prepared by introducing triethylenetetramine into folic acid with EDCI/NHS and characterized by IR, NMR and mass spectra. It was found that approximately one of two carboxyls in the folic acid molecule was substituted to form CFA. The conversion of -carboxyl is found to be 59% higher than 30% of -carboxyl. The CFA and doxorubicin hydrochloride can be loaded on the ionic shell of PTX-encapsulated micelle to form CFA loaded binary drug carrier via static interaction in aqueous solutions. The successful loading was demonstrated by zeta potential measurement and the drug load amount (DLA) of CFA was measured by HPLC. In vitro cytotoxicity results revealed the CFA drug carrier showed higher cytotoxicity to cancer cell MDA-MB-321 than the binary drug carrier without CFA and the positive control, while it showed lower cytotoxicity to normal cell HUVEC than the positive control, and similar cytotoxicity with the binary drug carrier without CFA. These results as well as confocal laser scanning microscopy observation indicate the synthesized CFA drug carrier possesses active tumor-targeting property.

Inspired by the photoprotection, radical scavenging of melanin together with versatile adhesive ability of mussel proteins, polydopamine (PDA) nanoparticles were successfully prepared and incorporated into environmentally friendly polymer, poly(propylene carbonate) (PPC) via solvent blending. The prepared composites exhibited excellent thermal stability in air and nitrogen atmosphere and extraordinary mechanical properties. The composites displayed eminent increase of temperature at 5% weight loss (T5%) by 30-100 K with 0.3 wt%-2.0 wt% loadings, meanwhile, the tensile strength and Young's modulus were significantly improved from 11.5 MPa and 553.7 MPa to 40.5 MPa and 2411.2 MPa, respectively. The kinetic calculation indicated that improvement of T5% is presumably derived from suppressing chain-end unzipping. The glass transition temperature (Tg) of the PPC/PDA composites increased by 8-10 K. This is probably due to hydrogen bondinginteraction since the abundant proton donors along PDA chains would interact with proton acceptors like C＝O and C―O―C in PPC which would cause restriction of segmental motion of PPC chains.