LAMINATION OF POLYMER FILMS BY BULK SURFACE PHOTOGRAFTING PROCESS AND PROPERTIES

A new process for lamination of polymer films by 'bulk surface photografting' has been developed. The chemical component of the invention is that the curing of reactive solution between two substrates is initiated by the surface free radicals produced by aromatic ketones and surface-hydrogen of substrates. Using the new approach, two or more polymer films are bonded together by a grafted polymer network which is grafted to adjacent substrate surfaces. The technique has been applied to film substrates of different polymers such as polyolefins, polyesters, and polyamides which have abstractable hydrogens at the surface. The photolaminated film composites containing carrier films and an intermediate functional film of low permeability give strong laminates with high barrier properties, e.g, for oxygen and air.

PERFORMANCE AND INITIATION MECHANISM OF ISOPROPYLTHIOXANTHONE IN SURFACE PHOTOGRAFTING

In a polymerization model with low density polyethylene (LDPE) as the substrate and acrylic acid (AA) as the monomer, the performance of isopropylthioxanthone (ITX) in initiating surface photografting polymerization was evaluated. The results show that the reactivity of photopolymerization and photografting of ITX locate between benzophenone (BP) and benzildimethylketal (BDK) for polymerization, BDK > ITX > BP; for surface grafting polymerization, BP > ITX > BDK. These results can be explained by a reaction mechanism of the inter-molecular or intra-molecular hydrogen abstraction reaction of ITX.

VAPOR PHASE PHOTOGRAFTING OF ACRYLIC ACID ON PE FIBERS

The surface of high strength and high modulus polyethylene (PE) fiber has been modified bygrafting with acrylic acid.Benzophenone and acrylic acid in vapor phase were UV-irradiated in thepresence of the PE tiber substrate.Grafting with acrylic acid took place in a thin layer on the sur-face,thus increasing the surface adhesion of PE fiber with epoxy resin.This paper dealt withphoto-polymerization reactions including the role of photoinitiator.The degree of graft increasedwith the enhancing of reaction time,reaction temperature and concentration of initiator.Acetonewas used as carriers of monomer and tiator and able to initiate and promote grafting to the sur-face.ATR-IR and SEM measurements on the grafted surface showed that some polar groups wereintroduced to the surface of PE fibers.Oligomer which existed during the polymerization could beremoved by washing with benzene.

A novel method to prepare SPR sensor chips based on photografting molecularly imprinted polymer

A novel method to prepare surface plasmon resonance（SPR） sensor chips based on grafted imprinted polymer is explored. Benzophenone photografting system is used to grow molecularly imprinted polymer（MIP） films from the modified surface of gold substrate.The surface morphology and thickness of MIP films were investigated by scanning electronic microscope（SEM）.The adsorption properties of sensor chip were studied by SPR spectroscopy.The results demonstrate that nano-MIP films can be constructed on the surface of gold substrate with the good adsorption of template molecules.

Gas-initiation under UV and liquid-grafting polymerization on the surface of polysulfone hollow fiber ultrafiltration membrane by dynamic method

Using the inner-surface of polysulfone hollow fiber ultrafiltration membranes as grafted layer, the method of gas-initiation and liquid-polymerization has been studied, which aimed to adjust the diameter of the pores in the membranes. The degree of polymerization varied with the changes of the parameters, such as irradiation time, monomer concentration, temperature and time of polymerization and so on. The results indicated that using benzophenone(BP) which is in a gaseous condition as photo-initiator, acrylamide as graft monomer, the polyacrylamide chain was grafted on the surface of membranes. After the surface membrane being modified, the water flux and retention altered,and thus it can be seen that the diameter of the pores in the membrane was altered. These experiments contribute to finding a new way to produce the hollow fiber membrane with the small pore size and are extraordinarily worth developing and studying.

Photochemical surface modification of poly(arylsulfone) ultrafiltration membrane and covalent immobilization of enzyme

The sensitivity of poly(arylsulfone)(PSf) for UV irradiation in different solvents(water and ethanol) was investigated. It is confirmed that acrylic acid(AA) and acrylamide(AAm) are grafted only onto the surface of the membrane instead of the interior by FTIR and scanning electron microscope(SEM). The membrane performance(Δ J/J 0 and contact angle θ ) after photografting was studied. In the range of conditions used, the grafting yield increases with irradiation time and monomer concentration growing. After photografting and N 3 dimethyl aminopropyl N' ethycarbodiimide hydrochloride(EDC) activation, PSf membrane was immobilized with hydrogen peroxide oxidoreductase, and showed a higher activity than the control membrane.

An inkjet printing soft photomask and its application on organic polymer substrates

This article presents a simple,fast and low-cost method to fabricate a flexible UV light photomask.The designed micropatterns were directly printed onto transparent hybrid composite film of biaxially oriented polypropylene coated with silica oxide (BOPP-SiOx) by an inkjet printer.Compared to the conventional chrome-mask,it is of advantages such as suitable for non-planar substrates,scalable for large area production,and extreme low cost.Combined with the confined photo-catalytic oxidation (CPO) reaction,the printed flexible BOPP-SiOx photomask was successfully used to pattern the shape of wettability of organic polymer surfaces,and then polyaniline patterns were deposited on the modified substrates with strong adhesion.With the above photomasks,the polyacrylic acid graft chains were duplicated on the poly (ethylene terephthalate) (PET) and BOPP substrates by photografting polymerization.We grafted polyacrylic acid (PAA) on a non-planar plastic substrate with this soft and thin plastic photomask.Scanning electron microscopy (SEM) and optical microscopy were used to characterize the surface morphology and thickness of ink layers of the printed photomask.Optical microscopy was used to characterize the deposition polyaniline micropatterns.It was found that the desired patterns were precisely printed on the modified polymer films and were applied in modifying organic polymer substrates.The printed photomask could be exploited in the fields such as prototype microfluidics,micro-sensors,optical structures and any other kind of microstructures which does not require high durability and dimensional stability.

Surface modification of biomaterials by photochemical immobilization and photograft polymerization to improve hemocompatibility

Thrombus formation and blood coagulation are serious problems associated with blood contacting products,such as catheters,vascular grafts,artificial hearts,and heart valves.Recent progresses and strategies to improve the hemocompatibility of biomaterials by surface modification using photochemical immobilization and photograft polymerization are reviewed in this paper.Three approaches to modify biomaterial surfaces for improving the hemocompatibility,i.e.,bioinert surfaces,immobilization of anticoagulative substances and biomimetic surfaces,are introduced.The biomimetic amphiphilic phosphorylcholine and Arg-Gly-Asp(RGD)sequence are the most effective and most often employed biomolecules and peptide sequence for improving hemocompatibility of material surfaces.The RGD sequence can enhance adhesion and growth of endothelial cells(ECs)on material surfaces and increase the retention of ECs under flow shear stress conditions.This surface modification is a promising strategy for biomaterials especially for cardiovascular grafts and functional tissue engineered blood vessels.