Effects of irradiation with vacuum ultraviolet xenon excimer lamp at 172 nm on water vapor transport through poly(lactic acid) membranes
Highlights
► Surface modification of amorphous PLA was performed with VUV excimer lamp. ► VUV caused surface photo-oxidation, scission reaction, and crystallization of PLA. ► Water vapor permeability at low pressure showed diffusivity-controlled behavior.
Introduction
Poly(lactic acid) (PLA) is an environmentally friendly biodegradable polymer substance with low melting point and good moldability. PLA is used as a material in packaging, electronic, and automobile applications. For such applications, water vapor permeability is an important factor in preventing material degradation because the material is exposed to air during their use.
On the other hand, surface modification technologies have been extensively used in the material industrial fields, and they play an important role in improving general materials [1]. In particular, surface modification by ultraviolet (UV) irradiation has been applied to various materials such as polymers, glasses, ceramics, and metals [2]. For such a surface modification technology, vacuum ultraviolet (VUV) by excimer lamp irradiation enables irradiation in conditions of atmospheric pressure and lower temperature with no damage to the materials. The VUV modification process by excimer lamp is also faster than the low pressure mercury lamp for high generative capacity of oxygen radicals [3]. For such characteristics, this surface modification technology is generally used for the development of the adhesion of materials and surface cleaning [4], [5], [6]. However, the water vapor transport properties of such surface-modified polymer membranes have yet to be studied.
Hence, in the current study, surface modification of PLA membrane was performed with a 172 nm VUV excimer lamp. The effects of VUV irradiation on the bulk and surface properties, as well as their PLA membrane structure were studied. Moreover, the water vapor transport properties (i.e., diffusivity, solubility, and permeability) of VUV-irradiated PLA membrane were systematically investigated. This is the first study on PLA membranes irradiated with VUV xenon excimer lamp at 172 nm and on the water vapor permeation properties of surface-modified polymer membranes.
Section snippets
Preparation of membranes
The PLA membranes were the same samples employed in our previous study [7]. The PLA polymer used in this study had a 4032D product (NatureWorks LLC, Minnetonka, USA). The isomer ratio was in the range of L:D = 96.0:4.0–96.8:3.2. PLA membranes were prepared by casting 2 wt.% dichloromethane solution of each solvent onto a flat-bottomed Petri dish in a glass bell-type vessel, and then drying under atmospheric pressure at room temperature. Each solvent was allowed to evaporate for 48 h. The dried PLA
Membrane bulk characterization
Bulk properties of the VUV-irradiated and unirradiated PLA membrane were systematically studied. The photographs of the PLA membrane for VUV-irradiated and unirradiated PLA membranes are presented in Fig. 1. The UV–vis spectra of these PLA membranes are shown in Fig. 2. The transmittance of their PLA membranes did not change in the 400–700 nm range, and the values were higher than 90%. However, almost no transmittance was found at values below 200 nm. This result indicated that the photon with 172
Conclusions
Surface modification of amorphous PLA membrane was performed by 172 nm excimer lamp irradiation. Water vapor and nitrogen transport properties (i.e., diffusivity, solubility, and permeability) of the VUV-irradiated PLA membrane were systematically investigated. We discovered the surface photo-oxidation, scission reaction, and crystallization of PLA membranes by VUV irradiation. The PLA chemical structural changed as chain cleavage and formation of CC double bonds and hydroperoxide OH at newly
References (27)
- et al.
VUV processing of polymers: surface modification and deposition of organic thin films
Nucl. Instrum. Methods Phys. Res. B
(2007) - et al.
Improved adhesion to polymers by UV/ozone surface oxidation
Int. J. Adhes. Adhes.
(1996) - et al.
Nano roughening of PET and PTT fabrics via continuous UV/O3 irradiation
Dye. Pigment.
(2006) - et al.
Immobilization of poly(ethylene glycol) or its sulfonate onto polymer surfaces by ozone oxidation
Biomaterials
(2001) - et al.
Permeability, diffusivity, and solubility of benzene vapor and water vapor in high free volume silicon- or fluorine-containing polymer membranes
J. Membr. Sci.
(2010) - et al.
Processing, annealing and sterilisation of poly-l-lactide
Biomaterials
(2004) - et al.
Preparation and characterization of biodegradable PLA polymeric blends
Biomaterials
(2003) - et al.
In vitro study of poly(lactic acid) in degradation
Polymer
(1999) - et al.
Characterization and gas transport properties of poly(lactic acid) blend membranes
Desalination
(2008) - et al.
Thermal and mechanical characteristics of poly(l-lactic acid) nanocomposite scaffold
Biomaterials
(2003)
Controlled preparation and properties of porous poly(l-lactide) obtained from a co-continuous blend of two biodegradable polymers
Biomaterials
Environmental degradation of biodegradable polyesters 1. Poly(ε-caprolactone), poly[(R)-3-hydroxybutyrate], and poly(l-lactide) films in controlled static seawater
Polym. Degrad. Stab.
Synthesis and characterization of functional l-lactic acid/citric acid oligomer
Eur. Polym. J.
Cited by (20)
Investigating the structural effect of electrospun nano-fibrous polymeric films on water vapor transmission
2019, Chinese Journal of Chemical EngineeringGas separation in polyimide membranes with molecular sieve-like chemical/physical dual crosslink elements onto the top of surface
2018, Journal of Membrane ScienceCitation Excerpt :VUV does not enter into the membrane and can only be modified on the top membrane surface. Previous studies reported the influence of VUV irradiation on the surface characteristics and high-order structure of poly(lactic)acid (PLA) and poly(1-trimethylsilyl-1-propyne) (PTMSP) [9,10]. The reactive hydroxyl groups are thus predicted to form on the top membrane surface by VUV irradiation.
Recent advances on the ageing of flame retarded PLA: Effect of UV-light and/or relative humidity
2017, Polymer Degradation and StabilityCitation Excerpt :This study confirms that the molecular mass is a key parameter in the durability of polymeric materials and especially of flame retarded PLA. The effects of UV light on the degradation of neat PLA have been widely studied over the years [13–15,17–20,46–48]. Depending on the UV irradiation wavelength, two photo-degradation mechanisms have been evidenced.
Hydrophilic molecular sieve surface layer formation in hydrophobic poly(1-trimethylsilyl-1-propyne) membranes
2013, Journal of Membrane ScienceCitation Excerpt :In this study, the surface modification of PTMSP membranes was performed with a 172 nm vacuum-ultraviolet (VUV) excimer lamp. VUV irradiation enables irradiation at atmospheric pressure and at low temperature conditions without any damage to the materials, in contrast to the sputtering and vapor deposition technologies [18]. VUV modification by an excimer lamp is likewise faster than that by a low-pressure mercury lamp in terms of the high capacity to generate oxygen radicals [19,20].
Room-temperature processed TiO<inf>2</inf> to construct composite electron transport layers for efficient planar perovskite solar cells
2023, Journal of Materials Chemistry A