Two-photon polymerization: investigation of chemical and mechanical properties of resins using Raman microspectroscopy

Jiang, Li; Zhou, Yun Shen; Xiong, Wei; Gao, Yang; Huang, Xi; Jiang, Lan; Baldacchini, Tommaso; Silvain, Jean François; Lu, Yong Feng

doi:10.1364/ol.39.003034

Cited by 125 publications

(120 citation statements)

References 31 publications

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“…This is in line with previous reports using Raman spectroscopy to determine the degree of crosslinking. At the reported laser intensities the irradiation converts the functionalised prepolymers into a crosslinked polymer, while higher pulse energies are needed for further chemical conversion of the polymer and carbonisation by the laser [68,69].…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Characterization and 3D Micro-Structuring via 2-Photon Polymerization of Poly(glycerol sebacate)-Methacrylate–An Elastomeric Degradable Polymer

et al. 2018

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Poly(glycerol sebacate) (PGS) has been utilized in numerous biomaterial applications over recent years. This elastomeric and rapidly degradable polymer is cytocompatible and suited to various applications in soft tissue engineering and drug delivery. Although PGS is simple to synthesize as an insoluble prepolymer, it requires the application of high temperatures for extended periods of time to produce an insoluble matrix. This places limitations on the processing capabilities of PGS and its possible applications. Here, we present a photocurable form of PGS with improved processing capabilities: PGS-methacrylate (PGS-M). By methacrylating the secondary hydroxyl groups of the glycerol units in the PGS prepolymer chains, the material was rendered photocurable and, in combination with a photoinitiator, crosslinked rapidly on exposure to UV light at ambient temperatures. The polymer's molecular weight and the degree of methacrylation could be controlled independently and the mechanical properties of the crosslinked material tailored. The polymer also displayed rapid degradation under physiological conditions and cytocompatibility with various primary cell types. As a demonstration of the processing capabilities of PGS-M, µm scale 3D scaffold structures were fabricated using 2-photon polymerization and used for 3D cell culture. The tunable properties of PGS-M coupled with its enhanced processing capabilities make the polymer an attractive potential biomaterial for various future applications.

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Section: Resultsmentioning

confidence: 99%

Synthesis, Characterization and 3D Micro-Structuring via 2-Photon Polymerization of Poly(glycerol sebacate)-Methacrylate–An Elastomeric Degradable Polymer

et al. 2018

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“…[8][9][10] Pure optical light delivery at tight focusing cannot explain the fi nal size of the structure, due to the threshold effect of laser modifi cation via polymerization/ crosslinking, thermal effects within the 3D focal volume, and wet chemistry development, which all affect the fi nal shape and size of the 3D structure. [11][12][13][14][15] Heat accumulation at the focus, defi ned by pulse repetition rate and scan speed, is used to increase the productivity of 3D polymerization and makes thermal issues very important and actively debated. [16][17][18] Polarization effects in laser fabrication in 2D and 3D geometries are now explored in polymerization by DLW.…”

Section: Doi: 101002/adom201600155mentioning

confidence: 99%

Nanoscale Precision of 3D Polymerization via Polarization Control

Rekštytė

Jonavičius

Gailevičius

et al. 2016

Advanced Optical Materials

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COMMUNICATIONand as self-organized nanopatterns induced on a surface, [ 30 ] are among other polarization-related phenomena demonstrated recently.The infl uence of beam polarization orientation on laser processing has been thoroughly studied in the cases of conductive and dielectric solid targets. [ 31,32 ] There are known effects of polarization on the scalar parameters of laser-matter interaction, such as absorption coeffi cient and ionization rate. [33][34][35][36] It is also known that heat conduction fl ux (vector) in plasma might be dependent on the direction of the imposed fi eld. [ 37 ] In what follows, these effects are considered in succession: (i) accumulation from multiple pulses, (ii) effects of polarization under high-numerical aperture (NA) focusing, and (iii) the infl uence of the external high-frequency electric fi eld on electronic heat conduction. The latter contribution has not yet been considered in laser fabrication under tight focusing. All these photomodifi cation mechanisms occur simultaneously and affect polymerization, which takes approximately a millisecond for common photoresists [ 38 ] at a >90% voxel overlap at typical writing velocity of 100 µm s -1 for widespread laser 3D nanolithography. [ 39 ] In this paper, a systematic analysis via modeling and experiments is presented in order to reveal polarization effects, their infl uence on the feature size (resolution), and the coupling between thermal gradient and polarization in DLW.To study and demonstrate the polarization effects, 3D suspended resolution bridges at various angles, α , between the linear polarization and scanning direction were fabricated on a glass substrate ( Figure 1 inset in (a); see details in the Experimental Section). The line-width difference was 10%-20% (varying exposure) under typical polymerization conditions for the linearly polarized pulses. The largest width of a 3D bridge was observed when the scan direction was perpendicular to the orientation of linear polarization, α = π / 2 ( E ⊥ v s ). The heightto-width ratio of the suspended lines was dependent on the orientation of linear polarization and changed between 3.07 and 3.44; self-focusing was not present under our experimental conditions. [ 40 ] Detailed analysis of polarization, threshold, and heat accumulation effects, which are all important, are discussed next.For the experimental conditions used, the focal spot diameter (at 1/ e 2 ) can be calculated as d f = 1.22 λ /NA = 898 nm assuming, for simplicity, a Gaussian intensity profi le. However, at such tight focusing it is necessary to use the vectorial Debye theory (specifi cs [ 41 ] can be found in Section A, Supporting Information), which predicts an ellipsoidal focal spot with two lateral cross sections: W l = 790 nm and W s = 572 nm for long and short cross sections, respectively (or 500 and 360 nm at full width at half maximum (FWHM)) for the actual experimental

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“…Examples are photocalorimetric measurements [15], or real-time Fourier transform infrared spectroscopy [16]. Very briefly, the double bonds within the acrylate groups are homolytically opened and converted to single bonds (C-C), so that the relative height of the corresponding Raman peak (C=C) is lowered during polymerization with respect to the unchanged carbonyl peak (C=O), which serves as a reference [19]. The methods of choice are therefore mostly based on Raman spectroscopy [17][18][19].…”

Section: Monomer Conversionmentioning

confidence: 99%