Jen-Ming Yang

Effects of additives on the photo-induced grafting polymerization of N-isopropylacrylamide gel onto PET film and PP nonwoven fabric surface

Abstract In this study, the thermosensitive gels were grafted onto plasma-activated polyethylene terephthalate (PET) film and polypropylene (PP) nonwoven fabric surface. The Ar* plasma pretreatment was carried out and subsequent photo-induced surface graft polymerization was employed to graft the N-isopropylacrylamide (NIPAAm). The effects of additives during the grafting were accessed. The additives used were ammonium peroxodisulfate (APS, initiator), N,N,N′,N′-tetra-methylethylene-diamine (TEMED, promoter) and N,N′-methylenebisacrylamide (NMBA, cross-linking agent). The results indicate that the additives of APS, TEMED and NMBA will be beneficial in promoting the grafting. The additives, including all three, will give the best result. These grafted gels exhibit a lower critical solution temperature (LCST) at about 32 °C, which shows that the temperature-responsive behavior of bulk P (NIPAAm) hydrogel was preserved.

Mechanical properties of acrylic bone cement containing PMMA-SiO2 hybrid sol-gel material.

An organic-inorganic hybrid material, poly(methyl methacrylate) (PMMA)-SiO2 (SiO2 content of 72 wt%), was prepared by incorporating PMMA structure units covalently into an SiO2 glass network via the sol-gel approach. The hybrid sol-gel material PMMA-SiO2 was subsequently used as the solid powder component of bone cement and its mechanical properties were evaluated. The effects of the addition of tricalcium phosphate (TCP), hydroxyethyl methacrylate (HEMA), and ethylene glycol dimethacrylate (EGDMA) on the properties of the sol-gel hybrid bone cement were also investigated. The influence of these components on the temperature rise during polymerization was discussed. It was found that the new bone cement containing PMMA-SiO2 hybrid sol-gel material had higher modulus than that of Simplex-P bone cement. The addition of TCP in the new bone cement increased the Youngs modulus and the polymerization time; the inverse was observed for the tensile, bending, and compressive strengths, and the polymerization temperature. The addition of HEMA and EGDMA in the new bone cement had the opposite effect of TCP. The comparison between the new sol-gel bone cement and the commercial Simplex P bone cement was discussed.

Preparation of heparin containing SBS-g-VP copolymer membrane for biomaterial usage

Abstract Vinyl pyridine (VP) was grafted onto styrene-butadiene-styrene (SBS) triblock copolymer membrane by UV-radiation induced graft copolymerization without degassing to obtain the SBS- g -VP copolymer membrane. The substituted pyridine groups on the SBS- g -VP graft copolymer membrane were quatermized with iodomethane, and then the membrane was treated with heparin to prepare the heparin containing SBS- g -VP copolymer membrane (SBS- g -VP-HEP). The SBS- g -VP and SBS- g -VP-HEP were characterized by electron spectroscopy for chemical analysis (ESCA). The heparin content was determined by toluidine blue heparin assay. The contact angles of dry and wet SBS- g -VP and SBS- g -VP-HEP with different amount of grafting and heparin content were determined. By using Kaelbles equation, the surface energies of SBS- g -VP and SBS- g -VP-HEP were determined. It was found that the surface energy and water content of SBS- g -VP and SBS- g -VP-HEP membrane increased with increasing graft amount and the heparin content, whereas the contact angle decreased. Protein adsorption of fibrinogen and albumin onto the membranes was also performed to evaluate the effect of graft amount and heparin content on the biocompatibility of SBS- g -VP and SBS- g -VP-HEP membranes. The amount of the adsorption of albumin and fibrinogen decreased with increasing grafting amount and heparin content.

Properties of modified hydroxyl-terminated polybutadiene based polyurethane membrane

Abstract One hydroxyl-terminated polybutadiene (HTPB) based polyurethane (PU) solution was prepared by reacting equal equivalent of 4,4-methylene diphenyl diisocyanate (MDI) and HTPB with 1,4-butanediol (BDO) as chain extender. The PU was then cast into membrane. The kinetic of epoxidation of HTPB-based PU membrane by an in situ generated peracid method was studied by infrared spectroscopy. The epoxidized PU membrane was named as EPU. The other HTPB-based PU with different molar ratios of dimethyol propionic acid (DPA) and 1,4-BDO as chain extender were synthesized by solution polymerization. The present PU was then cast into a membrane and named as PUDPA. 1-Ethyl-3-(3-dimethyamino propyl) carbodiimide (EDAC) was used in the linking reaction to graft heparin to PUDPA to get heparin containing PUDPA membrane and named as PUDPA-Hep. The membranes were subsequently characterized by the Fourier transform infrared spectroscopy and electron spectroscopy for chemical analysis (ESCA). The properties of PU such as density and gas permeation test were measured. Wettability and protein adsorption on the membranes were also evaluated from the water content, contact angle, and protein adsorptions of fibrinogen and albumin on the PU membrane. The diffusion coefficient of water in the membrane was determined in accordance with the Fickian diffusion mechanism. By using Kaelble’s equation and the contact angle data, the surface energy of PU membrane was determined. The protein adsorption of fibrinogen and albumin on PU membranes was evaluated. It was found that oxirane content in the EPU membrane increased with epoxidation time. The surface energy of EPU and PUDPA membranes increased with the increasing of oxirane content and DPA content on the EPU and PUDPA membrane, respectively, whereas the contact angle decreased inversely. The surface tension of wet EPU and PUDPA membrane was higher than that of dry EPU and PUDPA membrane, respectively. The adsorption of albumin and fibrinogen decreased with increasing the degree of epoxidation and the DPA content, respectively. After heparin treatment, the contact angel and protein absorption on PUDPA-Hep were lower than those on PUDPA.

Wettability and protein adsorption on HTPB-based polyurethane films

Abstract Hydroxyl-terminated polybutadiene-based (HTPB) polyurethane (PU) with different molar ratios of dimethyol propionic acid and 1,4-butane diol as the chain extender was synthesized by solution polymerization. The present PU was then cast into a membrane and subsequently characterized by the Fourier transform infrared spectroscopy. It was found that the participation of carbonyl group in hydrogen bonding increased with the content of dimethyol propionic acid in PU. The properties of the PU films including tensile strength and dynamic mechanical analysis (DMA) were studied. The tensile strength of PU films increased whereas the storage modulus decreased with increasing dimethyol propionic acid content. The glass transition temperature (Tg) of the PU film with only 1,4-butane diol as the chain extender was 4°C, while that of the films with dimethyol propionic acid as the chain extender was at about −15°C. Wettability and protein adsorption on the films were evaluated from the water content, contact angle, and protein adsorptions of fibrinogen and albumin on the PU films. The diffusion coefficient of water in the membrane was determined in accordance with the Fickian diffusion mechanism. No significant difference in the diffusion coefficient was observed for all the specimens. By using the Kaelble’s equation and the contact angle data, the surface tensions of the PU films with different amounts of dimethyol propionic acid were determined. The surface tension of PU film was found to increase with increasing dimethyol propionic acid content, while the opposite trend was observed for the contact angle and the amount of protein adsorption.

Preparation of poly(acrylic acid) modified polyurethane membrane for biomaterial by UV radiation without degassing

Poly(acrylic acid) modified polyurethane (AA/PU) membranes were prepared by UV radiation without degassing. The chemical composition of the AA/PU membrane was studied by IR spectroscopy. In addition to those absorption peaks associated with pure PU, the absorption peak at 2400 cm-1 of poly(AA) was also found. The morphology of AA/PU membrane was studied by optical polarizing microscopy. We also measured the glass transition temperature and the decomposition temperature of the AA/PU membrane by differential scanning calorimetry and thermogravimetric analysis. A significant domain was found in the AA/PU membrane, which resulted in different glass transition temperature and decomposition temperature between AA/PU and pure PU membrane. The effect of AA content on the contact angle and water absorption of the AA/PU membrane was determined. It was found that the water content of AA/PU membrane increased with increasing AA content, whereas the contact angle decreased. By using Kaebles equation and the contact angle data, the surface free energy of AA/PU membrane was determined. The increase of surface free energy resulted from the increase of the dispersion (gammad) term and polar (gammap) term. In order to evaluate the biocompatibility of these membranes, a cytotoxicity test and a cell adhesion and proliferation assay were conducted in cell culture. Immortal cells and primary lymphocytes were both used in this study. The results showed that these AA/PU membranes exhibited very low cytotoxicity and could support cell adhesion and growth. An animal primary test was also done in this study. It was found that the AA/PU membrane could possibly be employed in the treatment of bowel defect.

Preparation and characterization of heparin-containing SBS-g-DMAEMA copolymer membrane.

The grafting of dimethyl amino ethyl methacrylate (DMAEMA) onto styrene-butadiene-styrene triblock copolymer (SBS) membrane was subsequently conducted by UV-radiation induced graft copolymerization without degassing to obtain the SBS-g-DMAEMA copolymer membrane. The substituted amino groups on the SBS-g-DMAEMA graft copolymer membrane were quaternized with iodomethane, and then the membrane was treated with heparin to prepare the heparin-containing SBS-g-DMAEMA copolymer membrane (SBS-g-DMAEMA-HEP). The graft copolymer membrane (SBS-g-DMAEMA) and the heparin-containing SBS-g-DMAEMA copolymer membrane (SBS-g-DMAEMA-HEP) were characterized by FTIR spectroscopy. The heparin content was determined by toluidine blue heparin assay. Contact angle, water content, and protein adsorption of fibrinogen and albumin experiments were also performed to evaluate the effect of graft amount and heparin content on the biocompatibility of SBS-g-DMAEMA and SBS-g-DMAEMA-HEP graft copolymer membranes. By using Kaelbles equation, the surface tension of SBS-g-DMAEMA and SBS-g-DMAEMA-HEP were determined. It was found that with increasing grafting amount and the heparin content, the surface tension and water content of SBS-g-DMAEMA membrane increased, whereas the contact angle decreased. The amount of the adsorption of albumin and fibrinogen decreased with increasing graft amount and heparin content. However, there was a minimum for adsorption of proteins in the SBS-g-DMAEMA and SBS-g-DMAEMA-HEP membranes.

Preparation and properties of SBS-g-DMAEMA copolymer membrane by ultraviolet radiation

A styrene-butadiene-styrene triblock copolymer (SBS) membrane was prepared by solvent casting. Grafting of dimethyl amino ethyl methacrylate (DMAEMA) to this SBS membrane was subsequently conducted by ultraviolet radiation-induced graft copolymerization without degassing to obtain a SBS-g-DMAEMA copolymer membrane. The graft copolymer was characterized by infrared spectroscopy and scanning electron microscopy. The degree of grafting and the mechanical properties of SBS and SBS-g-DMAEMA were measured. Contact angle, water content, and protein absorption of fibrinogen and albumin experiments were also performed to evaluate the biocompatibility of SBS-g-DMAEMA graft copolymer membranes. It was found that the degree of grafting was related to the irradiation time, DMAEMA concentration, and temperature. The tensile strength of the SBS-g-DMAEMA membrane increased with an increase in the degree of grafting. By using Kaelbles equation and the contact angle data, the surface tension of SBS-g-DMAEMA was determined. It was found that with an increase in the degree of grafting, the surface tension and water content of SBS-g-DMAEMA membrane increased, whereas the contact angle decreased. The amount of absorption of albumin and fibrinogen decreased with an increase in amount of grafting. However, there was a minimum for the adsorption of proteins in the SBS-g-DMAEMA membrane.

Effect of MMA-g-UHMWPE grafted fiber on mechanical properties of acrylic bone cement.

Ultrahigh molecular weight polyethylene (UHMWPE) fibers were treated with argon plasma for 5 min, followed by uv irradiation in methyl methacrylate (MMA)-chloroform solution for 5 h to obtain MMA-g-UHMWPE grafted fiber. The grafting content was estimated by the titration of esterification method. The grafting amount of 5280 nmol/g was the largest for the MMA concentration at 18.75 vol%. To improve the mechanical properties of acrylic bone cement, pure UHMWPE fiber and MMA-g-UHMWPE fiber were added to the surgical Simplex. P radiopaque bone cement. The mechanical properties including tensile strength, tensile modulus, compressive strength, bending strength, and bending stiffness were measured. Dynamic mechanical analysis was also performed. By comparing the effect of the pure UHMWPE fiber and MMA-g-UHMWPE grafted fiber on the mechanical properties of acrylic bone cement, it was found that the acrylic bone cement with MMA-g-UHMWPE grafted fiber had a more significant reinforcing effect than that with untreated UHMWPE fiber. This might be due to the improvement of the interfacial bonding between the grafted fibers and the acrylic bone cement matrix.

Radiation-induced graft copolymer SBS-g-VP for biomaterial usage

The grafting of 4-vinyl pyridine (VP) to styrene-butadienestyrene triblock copolymer (SBS) by radiation-induced graft copolymerization was studied. The cohesive properties such as cohesive energy (Ecoh), molar volume (V), solubility parameter (delta), molar molecular weight (WM), specific volume (Vg), and density (1/Vg) of SBS-g-VP graft copolymer were calculated according to the group contribution of Fedors. The morphology of SBS-g-VP was studied by optical polarizing microscopy. We also measured the glass transition temperature and the mechanical properties of SBS-g-VP graft copolymer. Contact angle and blood-clotting time experiments were also performed to evaluate the biocompatibility of SBS-g-VP. A second domain was found in the SBS-g-VP graft copolymer, which resulted in different properties between SBS-g-VP and SBS. The blood compatibility of SBS-g-VP as measured by the Lee-White clotting test was better than that of SBS and polystyrene.